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core/num/
f32.rs

1//! Constants for the `f32` single-precision floating point type.
2//!
3//! *[See also the `f32` primitive type][f32].*
4//!
5//! Mathematically significant numbers are provided in the `consts` sub-module.
6//!
7//! For the constants defined directly in this module
8//! (as distinct from those defined in the `consts` sub-module),
9//! new code should instead use the associated constants
10//! defined directly on the `f32` type.
11
12#![stable(feature = "rust1", since = "1.0.0")]
13
14use crate::convert::FloatToInt;
15use crate::num::FpCategory;
16use crate::panic::const_assert;
17use crate::{cfg_select, intrinsics, mem};
18
19/// The radix or base of the internal representation of `f32`.
20/// Use [`f32::RADIX`] instead.
21///
22/// # Examples
23///
24/// ```rust
25/// // deprecated way
26/// # #[allow(deprecated, deprecated_in_future)]
27/// let r = std::f32::RADIX;
28///
29/// // intended way
30/// let r = f32::RADIX;
31/// ```
32#[stable(feature = "rust1", since = "1.0.0")]
33#[deprecated(since = "TBD", note = "replaced by the `RADIX` associated constant on `f32`")]
34#[rustc_diagnostic_item = "f32_legacy_const_radix"]
35pub const RADIX: u32 = f32::RADIX;
36
37/// Number of significant digits in base 2.
38/// Use [`f32::MANTISSA_DIGITS`] instead.
39///
40/// # Examples
41///
42/// ```rust
43/// // deprecated way
44/// # #[allow(deprecated, deprecated_in_future)]
45/// let d = std::f32::MANTISSA_DIGITS;
46///
47/// // intended way
48/// let d = f32::MANTISSA_DIGITS;
49/// ```
50#[stable(feature = "rust1", since = "1.0.0")]
51#[deprecated(
52    since = "TBD",
53    note = "replaced by the `MANTISSA_DIGITS` associated constant on `f32`"
54)]
55#[rustc_diagnostic_item = "f32_legacy_const_mantissa_dig"]
56pub const MANTISSA_DIGITS: u32 = f32::MANTISSA_DIGITS;
57
58/// Approximate number of significant digits in base 10.
59/// Use [`f32::DIGITS`] instead.
60///
61/// # Examples
62///
63/// ```rust
64/// // deprecated way
65/// # #[allow(deprecated, deprecated_in_future)]
66/// let d = std::f32::DIGITS;
67///
68/// // intended way
69/// let d = f32::DIGITS;
70/// ```
71#[stable(feature = "rust1", since = "1.0.0")]
72#[deprecated(since = "TBD", note = "replaced by the `DIGITS` associated constant on `f32`")]
73#[rustc_diagnostic_item = "f32_legacy_const_digits"]
74pub const DIGITS: u32 = f32::DIGITS;
75
76/// [Machine epsilon] value for `f32`.
77/// Use [`f32::EPSILON`] instead.
78///
79/// This is the difference between `1.0` and the next larger representable number.
80///
81/// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
82///
83/// # Examples
84///
85/// ```rust
86/// // deprecated way
87/// # #[allow(deprecated, deprecated_in_future)]
88/// let e = std::f32::EPSILON;
89///
90/// // intended way
91/// let e = f32::EPSILON;
92/// ```
93#[stable(feature = "rust1", since = "1.0.0")]
94#[deprecated(since = "TBD", note = "replaced by the `EPSILON` associated constant on `f32`")]
95#[rustc_diagnostic_item = "f32_legacy_const_epsilon"]
96pub const EPSILON: f32 = f32::EPSILON;
97
98/// Smallest finite `f32` value.
99/// Use [`f32::MIN`] instead.
100///
101/// # Examples
102///
103/// ```rust
104/// // deprecated way
105/// # #[allow(deprecated, deprecated_in_future)]
106/// let min = std::f32::MIN;
107///
108/// // intended way
109/// let min = f32::MIN;
110/// ```
111#[stable(feature = "rust1", since = "1.0.0")]
112#[deprecated(since = "TBD", note = "replaced by the `MIN` associated constant on `f32`")]
113#[rustc_diagnostic_item = "f32_legacy_const_min"]
114pub const MIN: f32 = f32::MIN;
115
116/// Smallest positive normal `f32` value.
117/// Use [`f32::MIN_POSITIVE`] instead.
118///
119/// # Examples
120///
121/// ```rust
122/// // deprecated way
123/// # #[allow(deprecated, deprecated_in_future)]
124/// let min = std::f32::MIN_POSITIVE;
125///
126/// // intended way
127/// let min = f32::MIN_POSITIVE;
128/// ```
129#[stable(feature = "rust1", since = "1.0.0")]
130#[deprecated(since = "TBD", note = "replaced by the `MIN_POSITIVE` associated constant on `f32`")]
131#[rustc_diagnostic_item = "f32_legacy_const_min_positive"]
132pub const MIN_POSITIVE: f32 = f32::MIN_POSITIVE;
133
134/// Largest finite `f32` value.
135/// Use [`f32::MAX`] instead.
136///
137/// # Examples
138///
139/// ```rust
140/// // deprecated way
141/// # #[allow(deprecated, deprecated_in_future)]
142/// let max = std::f32::MAX;
143///
144/// // intended way
145/// let max = f32::MAX;
146/// ```
147#[stable(feature = "rust1", since = "1.0.0")]
148#[deprecated(since = "TBD", note = "replaced by the `MAX` associated constant on `f32`")]
149#[rustc_diagnostic_item = "f32_legacy_const_max"]
150pub const MAX: f32 = f32::MAX;
151
152/// One greater than the minimum possible normal power of 2 exponent.
153/// Use [`f32::MIN_EXP`] instead.
154///
155/// # Examples
156///
157/// ```rust
158/// // deprecated way
159/// # #[allow(deprecated, deprecated_in_future)]
160/// let min = std::f32::MIN_EXP;
161///
162/// // intended way
163/// let min = f32::MIN_EXP;
164/// ```
165#[stable(feature = "rust1", since = "1.0.0")]
166#[deprecated(since = "TBD", note = "replaced by the `MIN_EXP` associated constant on `f32`")]
167#[rustc_diagnostic_item = "f32_legacy_const_min_exp"]
168pub const MIN_EXP: i32 = f32::MIN_EXP;
169
170/// Maximum possible power of 2 exponent.
171/// Use [`f32::MAX_EXP`] instead.
172///
173/// # Examples
174///
175/// ```rust
176/// // deprecated way
177/// # #[allow(deprecated, deprecated_in_future)]
178/// let max = std::f32::MAX_EXP;
179///
180/// // intended way
181/// let max = f32::MAX_EXP;
182/// ```
183#[stable(feature = "rust1", since = "1.0.0")]
184#[deprecated(since = "TBD", note = "replaced by the `MAX_EXP` associated constant on `f32`")]
185#[rustc_diagnostic_item = "f32_legacy_const_max_exp"]
186pub const MAX_EXP: i32 = f32::MAX_EXP;
187
188/// Minimum possible normal power of 10 exponent.
189/// Use [`f32::MIN_10_EXP`] instead.
190///
191/// # Examples
192///
193/// ```rust
194/// // deprecated way
195/// # #[allow(deprecated, deprecated_in_future)]
196/// let min = std::f32::MIN_10_EXP;
197///
198/// // intended way
199/// let min = f32::MIN_10_EXP;
200/// ```
201#[stable(feature = "rust1", since = "1.0.0")]
202#[deprecated(since = "TBD", note = "replaced by the `MIN_10_EXP` associated constant on `f32`")]
203#[rustc_diagnostic_item = "f32_legacy_const_min_10_exp"]
204pub const MIN_10_EXP: i32 = f32::MIN_10_EXP;
205
206/// Maximum possible power of 10 exponent.
207/// Use [`f32::MAX_10_EXP`] instead.
208///
209/// # Examples
210///
211/// ```rust
212/// // deprecated way
213/// # #[allow(deprecated, deprecated_in_future)]
214/// let max = std::f32::MAX_10_EXP;
215///
216/// // intended way
217/// let max = f32::MAX_10_EXP;
218/// ```
219#[stable(feature = "rust1", since = "1.0.0")]
220#[deprecated(since = "TBD", note = "replaced by the `MAX_10_EXP` associated constant on `f32`")]
221#[rustc_diagnostic_item = "f32_legacy_const_max_10_exp"]
222pub const MAX_10_EXP: i32 = f32::MAX_10_EXP;
223
224/// Not a Number (NaN).
225/// Use [`f32::NAN`] instead.
226///
227/// # Examples
228///
229/// ```rust
230/// // deprecated way
231/// # #[allow(deprecated, deprecated_in_future)]
232/// let nan = std::f32::NAN;
233///
234/// // intended way
235/// let nan = f32::NAN;
236/// ```
237#[stable(feature = "rust1", since = "1.0.0")]
238#[deprecated(since = "TBD", note = "replaced by the `NAN` associated constant on `f32`")]
239#[rustc_diagnostic_item = "f32_legacy_const_nan"]
240pub const NAN: f32 = f32::NAN;
241
242/// Infinity (∞).
243/// Use [`f32::INFINITY`] instead.
244///
245/// # Examples
246///
247/// ```rust
248/// // deprecated way
249/// # #[allow(deprecated, deprecated_in_future)]
250/// let inf = std::f32::INFINITY;
251///
252/// // intended way
253/// let inf = f32::INFINITY;
254/// ```
255#[stable(feature = "rust1", since = "1.0.0")]
256#[deprecated(since = "TBD", note = "replaced by the `INFINITY` associated constant on `f32`")]
257#[rustc_diagnostic_item = "f32_legacy_const_infinity"]
258pub const INFINITY: f32 = f32::INFINITY;
259
260/// Negative infinity (−∞).
261/// Use [`f32::NEG_INFINITY`] instead.
262///
263/// # Examples
264///
265/// ```rust
266/// // deprecated way
267/// # #[allow(deprecated, deprecated_in_future)]
268/// let ninf = std::f32::NEG_INFINITY;
269///
270/// // intended way
271/// let ninf = f32::NEG_INFINITY;
272/// ```
273#[stable(feature = "rust1", since = "1.0.0")]
274#[deprecated(since = "TBD", note = "replaced by the `NEG_INFINITY` associated constant on `f32`")]
275#[rustc_diagnostic_item = "f32_legacy_const_neg_infinity"]
276pub const NEG_INFINITY: f32 = f32::NEG_INFINITY;
277
278/// Basic mathematical constants.
279#[stable(feature = "rust1", since = "1.0.0")]
280#[rustc_diagnostic_item = "f32_consts_mod"]
281pub mod consts {
282    // FIXME: replace with mathematical constants from cmath.
283
284    /// Archimedes' constant (π)
285    #[stable(feature = "rust1", since = "1.0.0")]
286    pub const PI: f32 = 3.14159265358979323846264338327950288_f32;
287
288    /// The full circle constant (τ)
289    ///
290    /// Equal to 2π.
291    #[stable(feature = "tau_constant", since = "1.47.0")]
292    pub const TAU: f32 = 6.28318530717958647692528676655900577_f32;
293
294    /// The golden ratio (φ)
295    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
296    pub const GOLDEN_RATIO: f32 = 1.618033988749894848204586834365638118_f32;
297
298    /// The Euler-Mascheroni constant (γ)
299    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
300    pub const EULER_GAMMA: f32 = 0.577215664901532860606512090082402431_f32;
301
302    /// π/2
303    #[stable(feature = "rust1", since = "1.0.0")]
304    pub const FRAC_PI_2: f32 = 1.57079632679489661923132169163975144_f32;
305
306    /// π/3
307    #[stable(feature = "rust1", since = "1.0.0")]
308    pub const FRAC_PI_3: f32 = 1.04719755119659774615421446109316763_f32;
309
310    /// π/4
311    #[stable(feature = "rust1", since = "1.0.0")]
312    pub const FRAC_PI_4: f32 = 0.785398163397448309615660845819875721_f32;
313
314    /// π/6
315    #[stable(feature = "rust1", since = "1.0.0")]
316    pub const FRAC_PI_6: f32 = 0.52359877559829887307710723054658381_f32;
317
318    /// π/8
319    #[stable(feature = "rust1", since = "1.0.0")]
320    pub const FRAC_PI_8: f32 = 0.39269908169872415480783042290993786_f32;
321
322    /// 1/π
323    #[stable(feature = "rust1", since = "1.0.0")]
324    pub const FRAC_1_PI: f32 = 0.318309886183790671537767526745028724_f32;
325
326    /// 1/sqrt(π)
327    #[unstable(feature = "more_float_constants", issue = "146939")]
328    pub const FRAC_1_SQRT_PI: f32 = 0.564189583547756286948079451560772586_f32;
329
330    /// 1/sqrt(2π)
331    #[doc(alias = "FRAC_1_SQRT_TAU")]
332    #[unstable(feature = "more_float_constants", issue = "146939")]
333    pub const FRAC_1_SQRT_2PI: f32 = 0.398942280401432677939946059934381868_f32;
334
335    /// 2/π
336    #[stable(feature = "rust1", since = "1.0.0")]
337    pub const FRAC_2_PI: f32 = 0.636619772367581343075535053490057448_f32;
338
339    /// 2/sqrt(π)
340    #[stable(feature = "rust1", since = "1.0.0")]
341    pub const FRAC_2_SQRT_PI: f32 = 1.12837916709551257389615890312154517_f32;
342
343    /// sqrt(2)
344    #[stable(feature = "rust1", since = "1.0.0")]
345    pub const SQRT_2: f32 = 1.41421356237309504880168872420969808_f32;
346
347    /// 1/sqrt(2)
348    #[stable(feature = "rust1", since = "1.0.0")]
349    pub const FRAC_1_SQRT_2: f32 = 0.707106781186547524400844362104849039_f32;
350
351    /// sqrt(3)
352    #[unstable(feature = "more_float_constants", issue = "146939")]
353    pub const SQRT_3: f32 = 1.732050807568877293527446341505872367_f32;
354
355    /// 1/sqrt(3)
356    #[unstable(feature = "more_float_constants", issue = "146939")]
357    pub const FRAC_1_SQRT_3: f32 = 0.577350269189625764509148780501957456_f32;
358
359    /// sqrt(5)
360    #[unstable(feature = "more_float_constants", issue = "146939")]
361    pub const SQRT_5: f32 = 2.23606797749978969640917366873127623_f32;
362
363    /// 1/sqrt(5)
364    #[unstable(feature = "more_float_constants", issue = "146939")]
365    pub const FRAC_1_SQRT_5: f32 = 0.44721359549995793928183473374625524_f32;
366
367    /// Euler's number (e)
368    #[stable(feature = "rust1", since = "1.0.0")]
369    pub const E: f32 = 2.71828182845904523536028747135266250_f32;
370
371    /// log<sub>2</sub>(e)
372    #[stable(feature = "rust1", since = "1.0.0")]
373    pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
374
375    /// log<sub>2</sub>(10)
376    #[stable(feature = "extra_log_consts", since = "1.43.0")]
377    pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
378
379    /// log<sub>10</sub>(e)
380    #[stable(feature = "rust1", since = "1.0.0")]
381    pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
382
383    /// log<sub>10</sub>(2)
384    #[stable(feature = "extra_log_consts", since = "1.43.0")]
385    pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
386
387    /// ln(2)
388    #[stable(feature = "rust1", since = "1.0.0")]
389    pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
390
391    /// ln(10)
392    #[stable(feature = "rust1", since = "1.0.0")]
393    pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
394}
395
396#[doc(test(attr(allow(unused_features))))]
397impl f32 {
398    /// The radix or base of the internal representation of `f32`.
399    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
400    pub const RADIX: u32 = 2;
401
402    /// The size of this float type in bits.
403    #[unstable(feature = "float_bits_const", issue = "151073")]
404    pub const BITS: u32 = 32;
405
406    /// Number of significant digits in base 2.
407    ///
408    /// Note that the size of the mantissa in the bitwise representation is one
409    /// smaller than this since the leading 1 is not stored explicitly.
410    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
411    pub const MANTISSA_DIGITS: u32 = 24;
412
413    /// Approximate number of significant digits in base 10.
414    ///
415    /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
416    /// significant digits can be converted to `f32` and back without loss.
417    ///
418    /// Equal to floor(log<sub>10</sub>&nbsp;2<sup>[`MANTISSA_DIGITS`]&nbsp;&minus;&nbsp;1</sup>).
419    ///
420    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
421    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
422    pub const DIGITS: u32 = 6;
423
424    /// [Machine epsilon] value for `f32`.
425    ///
426    /// This is the difference between `1.0` and the next larger representable number.
427    ///
428    /// Equal to 2<sup>1&nbsp;&minus;&nbsp;[`MANTISSA_DIGITS`]</sup>.
429    ///
430    /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
431    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
432    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
433    #[rustc_diagnostic_item = "f32_epsilon"]
434    pub const EPSILON: f32 = 1.19209290e-07_f32;
435
436    /// Smallest finite `f32` value.
437    ///
438    /// Equal to &minus;[`MAX`].
439    ///
440    /// [`MAX`]: f32::MAX
441    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
442    pub const MIN: f32 = -3.40282347e+38_f32;
443    /// Smallest positive normal `f32` value.
444    ///
445    /// Equal to 2<sup>[`MIN_EXP`]&nbsp;&minus;&nbsp;1</sup>.
446    ///
447    /// [`MIN_EXP`]: f32::MIN_EXP
448    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
449    pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
450    /// Largest finite `f32` value.
451    ///
452    /// Equal to
453    /// (1&nbsp;&minus;&nbsp;2<sup>&minus;[`MANTISSA_DIGITS`]</sup>)&nbsp;2<sup>[`MAX_EXP`]</sup>.
454    ///
455    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
456    /// [`MAX_EXP`]: f32::MAX_EXP
457    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
458    pub const MAX: f32 = 3.40282347e+38_f32;
459
460    /// One greater than the minimum possible *normal* power of 2 exponent
461    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
462    ///
463    /// This corresponds to the exact minimum possible *normal* power of 2 exponent
464    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
465    /// In other words, all normal numbers representable by this type are
466    /// greater than or equal to 0.5&nbsp;×&nbsp;2<sup><i>MIN_EXP</i></sup>.
467    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
468    pub const MIN_EXP: i32 = -125;
469    /// One greater than the maximum possible power of 2 exponent
470    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
471    ///
472    /// This corresponds to the exact maximum possible power of 2 exponent
473    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
474    /// In other words, all numbers representable by this type are
475    /// strictly less than 2<sup><i>MAX_EXP</i></sup>.
476    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
477    pub const MAX_EXP: i32 = 128;
478
479    /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
480    ///
481    /// Equal to ceil(log<sub>10</sub>&nbsp;[`MIN_POSITIVE`]).
482    ///
483    /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
484    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
485    pub const MIN_10_EXP: i32 = -37;
486    /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
487    ///
488    /// Equal to floor(log<sub>10</sub>&nbsp;[`MAX`]).
489    ///
490    /// [`MAX`]: f32::MAX
491    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
492    pub const MAX_10_EXP: i32 = 38;
493
494    /// Not a Number (NaN).
495    ///
496    /// Note that IEEE 754 doesn't define just a single NaN value; a plethora of bit patterns are
497    /// considered to be NaN. Furthermore, the standard makes a difference between a "signaling" and
498    /// a "quiet" NaN, and allows inspecting its "payload" (the unspecified bits in the bit pattern)
499    /// and its sign. See the [specification of NaN bit patterns](f32#nan-bit-patterns) for more
500    /// info.
501    ///
502    /// This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions
503    /// that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is
504    /// guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary.
505    /// The concrete bit pattern may change across Rust versions and target platforms.
506    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
507    #[rustc_diagnostic_item = "f32_nan"]
508    #[allow(clippy::eq_op)]
509    pub const NAN: f32 = 0.0_f32 / 0.0_f32;
510    /// Infinity (∞).
511    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
512    pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
513    /// Negative infinity (−∞).
514    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
515    pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
516
517    /// Maximum integer that can be represented exactly in an [`f32`] value,
518    /// with no other integer converting to the same floating point value.
519    ///
520    /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
521    /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
522    /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
523    /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
524    /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
525    /// "one-to-one" mapping.
526    ///
527    /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
528    /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
529    /// ```
530    /// #![feature(float_exact_integer_constants)]
531    /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
532    /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
533    /// let max_exact_int = f32::MAX_EXACT_INTEGER;
534    /// assert_eq!(max_exact_int, max_exact_int as f32 as i32);
535    /// assert_eq!(max_exact_int + 1, (max_exact_int + 1) as f32 as i32);
536    /// assert_ne!(max_exact_int + 2, (max_exact_int + 2) as f32 as i32);
537    ///
538    /// // Beyond `f32::MAX_EXACT_INTEGER`, multiple integers can map to one float value
539    /// assert_eq!((max_exact_int + 1) as f32, (max_exact_int + 2) as f32);
540    /// # }
541    /// ```
542    #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
543    pub const MAX_EXACT_INTEGER: i32 = (1 << Self::MANTISSA_DIGITS) - 1;
544
545    /// Minimum integer that can be represented exactly in an [`f32`] value,
546    /// with no other integer converting to the same floating point value.
547    ///
548    /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
549    /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
550    /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
551    /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
552    /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
553    /// "one-to-one" mapping.
554    ///
555    /// This constant is equivalent to `-MAX_EXACT_INTEGER`.
556    ///
557    /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
558    /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
559    /// ```
560    /// #![feature(float_exact_integer_constants)]
561    /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
562    /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
563    /// let min_exact_int = f32::MIN_EXACT_INTEGER;
564    /// assert_eq!(min_exact_int, min_exact_int as f32 as i32);
565    /// assert_eq!(min_exact_int - 1, (min_exact_int - 1) as f32 as i32);
566    /// assert_ne!(min_exact_int - 2, (min_exact_int - 2) as f32 as i32);
567    ///
568    /// // Below `f32::MIN_EXACT_INTEGER`, multiple integers can map to one float value
569    /// assert_eq!((min_exact_int - 1) as f32, (min_exact_int - 2) as f32);
570    /// # }
571    /// ```
572    #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
573    pub const MIN_EXACT_INTEGER: i32 = -Self::MAX_EXACT_INTEGER;
574
575    /// The mask of the bit used to encode the sign of an [`f32`].
576    ///
577    /// This bit is set when the sign is negative and unset when the sign is
578    /// positive.
579    /// If you only need to check whether a value is positive or negative,
580    /// [`is_sign_positive`] or [`is_sign_negative`] can be used.
581    ///
582    /// [`is_sign_positive`]: f32::is_sign_positive
583    /// [`is_sign_negative`]: f32::is_sign_negative
584    /// ```rust
585    /// #![feature(float_masks)]
586    /// let sign_mask = f32::SIGN_MASK;
587    /// let a = 1.6552f32;
588    /// let a_bits = a.to_bits();
589    ///
590    /// assert_eq!(a_bits & sign_mask, 0x0);
591    /// assert_eq!(f32::from_bits(a_bits ^ sign_mask), -a);
592    /// assert_eq!(sign_mask, (-0.0f32).to_bits());
593    /// ```
594    #[unstable(feature = "float_masks", issue = "154064")]
595    pub const SIGN_MASK: u32 = 0x8000_0000;
596
597    /// The mask of the bits used to encode the exponent of an [`f32`].
598    ///
599    /// Note that the exponent is stored as a biased value, with a bias of 127 for `f32`.
600    ///
601    /// ```rust
602    /// #![feature(float_masks)]
603    /// fn get_exp(a: f32) -> i32 {
604    ///     let bias = 127;
605    ///     let biased = a.to_bits() & f32::EXPONENT_MASK;
606    ///     (biased >> (f32::MANTISSA_DIGITS - 1)).cast_signed() - bias
607    /// }
608    ///
609    /// assert_eq!(get_exp(0.5), -1);
610    /// assert_eq!(get_exp(1.0), 0);
611    /// assert_eq!(get_exp(2.0), 1);
612    /// assert_eq!(get_exp(4.0), 2);
613    /// ```
614    #[unstable(feature = "float_masks", issue = "154064")]
615    pub const EXPONENT_MASK: u32 = 0x7f80_0000;
616
617    /// The mask of the bits used to encode the mantissa of an [`f32`].
618    ///
619    /// ```rust
620    /// #![feature(float_masks)]
621    /// let mantissa_mask = f32::MANTISSA_MASK;
622    ///
623    /// assert_eq!(0f32.to_bits() & mantissa_mask, 0x0);
624    /// assert_eq!(1f32.to_bits() & mantissa_mask, 0x0);
625    ///
626    /// // multiplying a finite value by a power of 2 doesn't change its mantissa
627    /// // unless the result or initial value is not normal.
628    /// let a = 1.6552f32;
629    /// let b = 4.0 * a;
630    /// assert_eq!(a.to_bits() & mantissa_mask, b.to_bits() & mantissa_mask);
631    ///
632    /// // The maximum and minimum values have a saturated significand
633    /// assert_eq!(f32::MAX.to_bits() & f32::MANTISSA_MASK, f32::MANTISSA_MASK);
634    /// assert_eq!(f32::MIN.to_bits() & f32::MANTISSA_MASK, f32::MANTISSA_MASK);
635    /// ```
636    #[unstable(feature = "float_masks", issue = "154064")]
637    pub const MANTISSA_MASK: u32 = 0x007f_ffff;
638
639    /// Minimum representable positive value (min subnormal)
640    const TINY_BITS: u32 = 0x1;
641
642    /// Minimum representable negative value (min negative subnormal)
643    const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
644
645    /// Returns `true` if this value is NaN.
646    ///
647    /// ```
648    /// let nan = f32::NAN;
649    /// let f = 7.0_f32;
650    ///
651    /// assert!(nan.is_nan());
652    /// assert!(!f.is_nan());
653    /// ```
654    #[must_use]
655    #[stable(feature = "rust1", since = "1.0.0")]
656    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
657    #[inline]
658    #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
659    #[ferrocene::prevalidated]
660    pub const fn is_nan(self) -> bool {
661        self != self
662    }
663
664    /// Returns `true` if this value is positive infinity or negative infinity, and
665    /// `false` otherwise.
666    ///
667    /// ```
668    /// let f = 7.0f32;
669    /// let inf = f32::INFINITY;
670    /// let neg_inf = f32::NEG_INFINITY;
671    /// let nan = f32::NAN;
672    ///
673    /// assert!(!f.is_infinite());
674    /// assert!(!nan.is_infinite());
675    ///
676    /// assert!(inf.is_infinite());
677    /// assert!(neg_inf.is_infinite());
678    /// ```
679    #[must_use]
680    #[stable(feature = "rust1", since = "1.0.0")]
681    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
682    #[inline]
683    #[ferrocene::prevalidated]
684    pub const fn is_infinite(self) -> bool {
685        // Getting clever with transmutation can result in incorrect answers on some FPUs
686        // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
687        // See https://github.com/rust-lang/rust/issues/72327
688        (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
689    }
690
691    /// Returns `true` if this number is neither infinite nor NaN.
692    ///
693    /// ```
694    /// let f = 7.0f32;
695    /// let inf = f32::INFINITY;
696    /// let neg_inf = f32::NEG_INFINITY;
697    /// let nan = f32::NAN;
698    ///
699    /// assert!(f.is_finite());
700    ///
701    /// assert!(!nan.is_finite());
702    /// assert!(!inf.is_finite());
703    /// assert!(!neg_inf.is_finite());
704    /// ```
705    #[must_use]
706    #[stable(feature = "rust1", since = "1.0.0")]
707    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
708    #[inline]
709    pub const fn is_finite(self) -> bool {
710        // There's no need to handle NaN separately: if self is NaN,
711        // the comparison is not true, exactly as desired.
712        self.abs() < Self::INFINITY
713    }
714
715    /// Returns `true` if the number is [subnormal].
716    ///
717    /// ```
718    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
719    /// let max = f32::MAX;
720    /// let lower_than_min = 1.0e-40_f32;
721    /// let zero = 0.0_f32;
722    ///
723    /// assert!(!min.is_subnormal());
724    /// assert!(!max.is_subnormal());
725    ///
726    /// assert!(!zero.is_subnormal());
727    /// assert!(!f32::NAN.is_subnormal());
728    /// assert!(!f32::INFINITY.is_subnormal());
729    /// // Values between `0` and `min` are Subnormal.
730    /// assert!(lower_than_min.is_subnormal());
731    /// ```
732    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
733    #[must_use]
734    #[stable(feature = "is_subnormal", since = "1.53.0")]
735    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
736    #[inline]
737    pub const fn is_subnormal(self) -> bool {
738        matches!(self.classify(), FpCategory::Subnormal)
739    }
740
741    /// Returns `true` if the number is neither zero, infinite,
742    /// [subnormal], or NaN.
743    ///
744    /// ```
745    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
746    /// let max = f32::MAX;
747    /// let lower_than_min = 1.0e-40_f32;
748    /// let zero = 0.0_f32;
749    ///
750    /// assert!(min.is_normal());
751    /// assert!(max.is_normal());
752    ///
753    /// assert!(!zero.is_normal());
754    /// assert!(!f32::NAN.is_normal());
755    /// assert!(!f32::INFINITY.is_normal());
756    /// // Values between `0` and `min` are Subnormal.
757    /// assert!(!lower_than_min.is_normal());
758    /// ```
759    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
760    #[must_use]
761    #[stable(feature = "rust1", since = "1.0.0")]
762    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
763    #[inline]
764    pub const fn is_normal(self) -> bool {
765        matches!(self.classify(), FpCategory::Normal)
766    }
767
768    /// Returns the floating point category of the number. If only one property
769    /// is going to be tested, it is generally faster to use the specific
770    /// predicate instead.
771    ///
772    /// ```
773    /// use std::num::FpCategory;
774    ///
775    /// let num = 12.4_f32;
776    /// let inf = f32::INFINITY;
777    ///
778    /// assert_eq!(num.classify(), FpCategory::Normal);
779    /// assert_eq!(inf.classify(), FpCategory::Infinite);
780    /// ```
781    #[ferrocene::prevalidated]
782    #[stable(feature = "rust1", since = "1.0.0")]
783    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
784    #[must_use]
785    pub const fn classify(self) -> FpCategory {
786        // We used to have complicated logic here that avoids the simple bit-based tests to work
787        // around buggy codegen for x87 targets (see
788        // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
789        // of our tests is able to find any difference between the complicated and the naive
790        // version, so now we are back to the naive version.
791        let b = self.to_bits();
792        match (b & Self::MANTISSA_MASK, b & Self::EXPONENT_MASK) {
793            (0, Self::EXPONENT_MASK) => FpCategory::Infinite,
794            (_, Self::EXPONENT_MASK) => FpCategory::Nan,
795            (0, 0) => FpCategory::Zero,
796            (_, 0) => FpCategory::Subnormal,
797            _ => FpCategory::Normal,
798        }
799    }
800
801    /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
802    /// positive sign bit and positive infinity.
803    ///
804    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
805    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
806    /// conserved over arithmetic operations, the result of `is_sign_positive` on
807    /// a NaN might produce an unexpected or non-portable result. See the [specification
808    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
809    /// if you need fully portable behavior (will return `false` for all NaNs).
810    ///
811    /// ```
812    /// let f = 7.0_f32;
813    /// let g = -7.0_f32;
814    ///
815    /// assert!(f.is_sign_positive());
816    /// assert!(!g.is_sign_positive());
817    /// ```
818    #[must_use]
819    #[stable(feature = "rust1", since = "1.0.0")]
820    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
821    #[inline]
822    pub const fn is_sign_positive(self) -> bool {
823        !self.is_sign_negative()
824    }
825
826    /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
827    /// negative sign bit and negative infinity.
828    ///
829    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
830    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
831    /// conserved over arithmetic operations, the result of `is_sign_negative` on
832    /// a NaN might produce an unexpected or non-portable result. See the [specification
833    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
834    /// if you need fully portable behavior (will return `false` for all NaNs).
835    ///
836    /// ```
837    /// let f = 7.0f32;
838    /// let g = -7.0f32;
839    ///
840    /// assert!(!f.is_sign_negative());
841    /// assert!(g.is_sign_negative());
842    /// ```
843    #[must_use]
844    #[stable(feature = "rust1", since = "1.0.0")]
845    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
846    #[inline]
847    #[ferrocene::prevalidated]
848    pub const fn is_sign_negative(self) -> bool {
849        // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
850        // applies to zeros and NaNs as well.
851        self.to_bits() & 0x8000_0000 != 0
852    }
853
854    /// Returns the least number greater than `self`.
855    ///
856    /// Let `TINY` be the smallest representable positive `f32`. Then,
857    ///  - if `self.is_nan()`, this returns `self`;
858    ///  - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
859    ///  - if `self` is `-TINY`, this returns -0.0;
860    ///  - if `self` is -0.0 or +0.0, this returns `TINY`;
861    ///  - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
862    ///  - otherwise the unique least value greater than `self` is returned.
863    ///
864    /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
865    /// is finite `x == x.next_up().next_down()` also holds.
866    ///
867    /// ```rust
868    /// // f32::EPSILON is the difference between 1.0 and the next number up.
869    /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
870    /// // But not for most numbers.
871    /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
872    /// assert_eq!(16777216f32.next_up(), 16777218.0);
873    /// ```
874    ///
875    /// This operation corresponds to IEEE-754 `nextUp`.
876    ///
877    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
878    /// [`INFINITY`]: Self::INFINITY
879    /// [`MIN`]: Self::MIN
880    /// [`MAX`]: Self::MAX
881    #[inline]
882    #[doc(alias = "nextUp")]
883    #[stable(feature = "float_next_up_down", since = "1.86.0")]
884    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
885    #[must_use = "method returns a new number and does not mutate the original value"]
886    pub const fn next_up(self) -> Self {
887        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
888        // denormals to zero. This is in general unsound and unsupported, but here
889        // we do our best to still produce the correct result on such targets.
890        let bits = self.to_bits();
891        if self.is_nan() || bits == Self::INFINITY.to_bits() {
892            return self;
893        }
894
895        let abs = bits & !Self::SIGN_MASK;
896        let next_bits = if abs == 0 {
897            Self::TINY_BITS
898        } else if bits == abs {
899            bits + 1
900        } else {
901            bits - 1
902        };
903        Self::from_bits(next_bits)
904    }
905
906    /// Returns the greatest number less than `self`.
907    ///
908    /// Let `TINY` be the smallest representable positive `f32`. Then,
909    ///  - if `self.is_nan()`, this returns `self`;
910    ///  - if `self` is [`INFINITY`], this returns [`MAX`];
911    ///  - if `self` is `TINY`, this returns 0.0;
912    ///  - if `self` is -0.0 or +0.0, this returns `-TINY`;
913    ///  - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
914    ///  - otherwise the unique greatest value less than `self` is returned.
915    ///
916    /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
917    /// is finite `x == x.next_down().next_up()` also holds.
918    ///
919    /// ```rust
920    /// let x = 1.0f32;
921    /// // Clamp value into range [0, 1).
922    /// let clamped = x.clamp(0.0, 1.0f32.next_down());
923    /// assert!(clamped < 1.0);
924    /// assert_eq!(clamped.next_up(), 1.0);
925    /// ```
926    ///
927    /// This operation corresponds to IEEE-754 `nextDown`.
928    ///
929    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
930    /// [`INFINITY`]: Self::INFINITY
931    /// [`MIN`]: Self::MIN
932    /// [`MAX`]: Self::MAX
933    #[inline]
934    #[doc(alias = "nextDown")]
935    #[stable(feature = "float_next_up_down", since = "1.86.0")]
936    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
937    #[must_use = "method returns a new number and does not mutate the original value"]
938    pub const fn next_down(self) -> Self {
939        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
940        // denormals to zero. This is in general unsound and unsupported, but here
941        // we do our best to still produce the correct result on such targets.
942        let bits = self.to_bits();
943        if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
944            return self;
945        }
946
947        let abs = bits & !Self::SIGN_MASK;
948        let next_bits = if abs == 0 {
949            Self::NEG_TINY_BITS
950        } else if bits == abs {
951            bits - 1
952        } else {
953            bits + 1
954        };
955        Self::from_bits(next_bits)
956    }
957
958    /// Takes the reciprocal (inverse) of a number, `1/x`.
959    ///
960    /// ```
961    /// let x = 2.0_f32;
962    /// let abs_difference = (x.recip() - (1.0 / x)).abs();
963    ///
964    /// assert!(abs_difference <= f32::EPSILON);
965    /// ```
966    #[must_use = "this returns the result of the operation, without modifying the original"]
967    #[stable(feature = "rust1", since = "1.0.0")]
968    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
969    #[inline]
970    pub const fn recip(self) -> f32 {
971        1.0 / self
972    }
973
974    /// Converts radians to degrees.
975    ///
976    /// # Unspecified precision
977    ///
978    /// The precision of this function is non-deterministic. This means it varies by platform,
979    /// Rust version, and can even differ within the same execution from one invocation to the next.
980    ///
981    /// # Examples
982    ///
983    /// ```
984    /// let angle = std::f32::consts::PI;
985    ///
986    /// let abs_difference = (angle.to_degrees() - 180.0).abs();
987    /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
988    /// assert!(abs_difference <= f32::EPSILON);
989    /// ```
990    #[must_use = "this returns the result of the operation, \
991                  without modifying the original"]
992    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
993    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
994    #[inline]
995    pub const fn to_degrees(self) -> f32 {
996        // Use a literal to avoid double rounding, consts::PI is already rounded,
997        // and dividing would round again.
998        const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
999        self * PIS_IN_180
1000    }
1001
1002    /// Converts degrees to radians.
1003    ///
1004    /// # Unspecified precision
1005    ///
1006    /// The precision of this function is non-deterministic. This means it varies by platform,
1007    /// Rust version, and can even differ within the same execution from one invocation to the next.
1008    ///
1009    /// # Examples
1010    ///
1011    /// ```
1012    /// let angle = 180.0f32;
1013    ///
1014    /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
1015    ///
1016    /// assert!(abs_difference <= f32::EPSILON);
1017    /// ```
1018    #[must_use = "this returns the result of the operation, \
1019                  without modifying the original"]
1020    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
1021    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1022    #[inline]
1023    pub const fn to_radians(self) -> f32 {
1024        // The division here is correctly rounded with respect to the true value of π/180.
1025        // Although π is irrational and already rounded, the double rounding happens
1026        // to produce correct result for f32.
1027        const RADS_PER_DEG: f32 = consts::PI / 180.0;
1028        self * RADS_PER_DEG
1029    }
1030
1031    /// Returns the maximum of the two numbers, ignoring NaN.
1032    ///
1033    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
1034    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1035    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1036    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1037    /// non-deterministically.
1038    ///
1039    /// The handling of NaNs follows the IEEE 754-2019 semantics for `maximumNumber`, treating all
1040    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1041    /// follows the IEEE 754-2008 semantics for `maxNum`.
1042    ///
1043    /// ```
1044    /// let x = 1.0f32;
1045    /// let y = 2.0f32;
1046    ///
1047    /// assert_eq!(x.max(y), y);
1048    /// assert_eq!(x.max(f32::NAN), x);
1049    /// ```
1050    #[must_use = "this returns the result of the comparison, without modifying either input"]
1051    #[stable(feature = "rust1", since = "1.0.0")]
1052    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1053    #[inline]
1054    #[ferrocene::prevalidated]
1055    pub const fn max(self, other: f32) -> f32 {
1056        intrinsics::maximum_number_nsz_f32(self, other)
1057    }
1058
1059    /// Returns the minimum of the two numbers, ignoring NaN.
1060    ///
1061    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
1062    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1063    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1064    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1065    /// non-deterministically.
1066    ///
1067    /// The handling of NaNs follows the IEEE 754-2019 semantics for `minimumNumber`, treating all
1068    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1069    /// follows the IEEE 754-2008 semantics for `minNum`.
1070    ///
1071    /// ```
1072    /// let x = 1.0f32;
1073    /// let y = 2.0f32;
1074    ///
1075    /// assert_eq!(x.min(y), x);
1076    /// assert_eq!(x.min(f32::NAN), x);
1077    /// ```
1078    #[must_use = "this returns the result of the comparison, without modifying either input"]
1079    #[stable(feature = "rust1", since = "1.0.0")]
1080    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1081    #[inline]
1082    #[ferrocene::prevalidated]
1083    pub const fn min(self, other: f32) -> f32 {
1084        intrinsics::minimum_number_nsz_f32(self, other)
1085    }
1086
1087    /// Returns the maximum of the two numbers, propagating NaN.
1088    ///
1089    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1090    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1091    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1092    /// non-NaN inputs.
1093    ///
1094    /// This is in contrast to [`f32::max`] which only returns NaN when *both* arguments are NaN,
1095    /// and which does not reliably order `-0.0` and `+0.0`.
1096    ///
1097    /// This follows the IEEE 754-2019 semantics for `maximum`.
1098    ///
1099    /// ```
1100    /// #![feature(float_minimum_maximum)]
1101    /// let x = 1.0f32;
1102    /// let y = 2.0f32;
1103    ///
1104    /// assert_eq!(x.maximum(y), y);
1105    /// assert!(x.maximum(f32::NAN).is_nan());
1106    /// ```
1107    #[must_use = "this returns the result of the comparison, without modifying either input"]
1108    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1109    #[inline]
1110    pub const fn maximum(self, other: f32) -> f32 {
1111        intrinsics::maximumf32(self, other)
1112    }
1113
1114    /// Returns the minimum of the two numbers, propagating NaN.
1115    ///
1116    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1117    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1118    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1119    /// non-NaN inputs.
1120    ///
1121    /// This is in contrast to [`f32::min`] which only returns NaN when *both* arguments are NaN,
1122    /// and which does not reliably order `-0.0` and `+0.0`.
1123    ///
1124    /// This follows the IEEE 754-2019 semantics for `minimum`.
1125    ///
1126    /// ```
1127    /// #![feature(float_minimum_maximum)]
1128    /// let x = 1.0f32;
1129    /// let y = 2.0f32;
1130    ///
1131    /// assert_eq!(x.minimum(y), x);
1132    /// assert!(x.minimum(f32::NAN).is_nan());
1133    /// ```
1134    #[must_use = "this returns the result of the comparison, without modifying either input"]
1135    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1136    #[inline]
1137    pub const fn minimum(self, other: f32) -> f32 {
1138        intrinsics::minimumf32(self, other)
1139    }
1140
1141    /// Calculates the midpoint (average) between `self` and `rhs`.
1142    ///
1143    /// This returns NaN when *either* argument is NaN or if a combination of
1144    /// +inf and -inf is provided as arguments.
1145    ///
1146    /// # Examples
1147    ///
1148    /// ```
1149    /// assert_eq!(1f32.midpoint(4.0), 2.5);
1150    /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1151    /// ```
1152    #[inline]
1153    #[doc(alias = "average")]
1154    #[stable(feature = "num_midpoint", since = "1.85.0")]
1155    #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1156    #[must_use = "this returns the result of the operation, \
1157                  without modifying the original"]
1158    pub const fn midpoint(self, other: f32) -> f32 {
1159        cfg_select! {
1160            // Allow faster implementation that have known good 64-bit float
1161            // implementations. Falling back to the branchy code on targets that don't
1162            // have 64-bit hardware floats or buggy implementations.
1163            // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1164            any(
1165                target_arch = "x86_64",
1166                target_arch = "aarch64",
1167                all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1168                all(target_arch = "loongarch64", target_feature = "d"),
1169                all(target_arch = "arm", target_feature = "vfp2"),
1170                target_arch = "wasm32",
1171                target_arch = "wasm64",
1172            ) => {
1173                ((self as f64 + other as f64) / 2.0) as f32
1174            }
1175            _ => {
1176                const HI: f32 = f32::MAX / 2.;
1177
1178                let (a, b) = (self, other);
1179                let abs_a = a.abs();
1180                let abs_b = b.abs();
1181
1182                if abs_a <= HI && abs_b <= HI {
1183                    // Overflow is impossible
1184                    (a + b) / 2.
1185                } else {
1186                    (a / 2.) + (b / 2.)
1187                }
1188            }
1189        }
1190    }
1191
1192    /// Rounds toward zero and converts to any primitive integer type,
1193    /// assuming that the value is finite and fits in that type.
1194    ///
1195    /// ```
1196    /// let value = 4.6_f32;
1197    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1198    /// assert_eq!(rounded, 4);
1199    ///
1200    /// let value = -128.9_f32;
1201    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1202    /// assert_eq!(rounded, i8::MIN);
1203    /// ```
1204    ///
1205    /// # Safety
1206    ///
1207    /// The value must:
1208    ///
1209    /// * Not be `NaN`
1210    /// * Not be infinite
1211    /// * Be representable in the return type `Int`, after truncating off its fractional part
1212    #[must_use = "this returns the result of the operation, \
1213                  without modifying the original"]
1214    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1215    #[inline]
1216    pub unsafe fn to_int_unchecked<Int>(self) -> Int
1217    where
1218        Self: FloatToInt<Int>,
1219    {
1220        // SAFETY: the caller must uphold the safety contract for
1221        // `FloatToInt::to_int_unchecked`.
1222        unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1223    }
1224
1225    /// Raw transmutation to `u32`.
1226    ///
1227    /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1228    ///
1229    /// See [`from_bits`](Self::from_bits) for some discussion of the
1230    /// portability of this operation (there are almost no issues).
1231    ///
1232    /// Note that this function is distinct from `as` casting, which attempts to
1233    /// preserve the *numeric* value, and not the bitwise value.
1234    ///
1235    /// # Examples
1236    ///
1237    /// ```
1238    /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1239    /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1240    ///
1241    /// ```
1242    #[must_use = "this returns the result of the operation, \
1243                  without modifying the original"]
1244    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1245    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1246    #[inline]
1247    #[allow(unnecessary_transmutes)]
1248    #[ferrocene::prevalidated]
1249    pub const fn to_bits(self) -> u32 {
1250        // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1251        unsafe { mem::transmute(self) }
1252    }
1253
1254    /// Raw transmutation from `u32`.
1255    ///
1256    /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1257    /// It turns out this is incredibly portable, for two reasons:
1258    ///
1259    /// * Floats and Ints have the same endianness on all supported platforms.
1260    /// * IEEE 754 very precisely specifies the bit layout of floats.
1261    ///
1262    /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1263    /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1264    /// (notably x86 and ARM) picked the interpretation that was ultimately
1265    /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1266    /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1267    ///
1268    /// Rather than trying to preserve signaling-ness cross-platform, this
1269    /// implementation favors preserving the exact bits. This means that
1270    /// any payloads encoded in NaNs will be preserved even if the result of
1271    /// this method is sent over the network from an x86 machine to a MIPS one.
1272    ///
1273    /// If the results of this method are only manipulated by the same
1274    /// architecture that produced them, then there is no portability concern.
1275    ///
1276    /// If the input isn't NaN, then there is no portability concern.
1277    ///
1278    /// If you don't care about signalingness (very likely), then there is no
1279    /// portability concern.
1280    ///
1281    /// Note that this function is distinct from `as` casting, which attempts to
1282    /// preserve the *numeric* value, and not the bitwise value.
1283    ///
1284    /// # Examples
1285    ///
1286    /// ```
1287    /// let v = f32::from_bits(0x41480000);
1288    /// assert_eq!(v, 12.5);
1289    /// ```
1290    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1291    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1292    #[must_use]
1293    #[inline]
1294    #[allow(unnecessary_transmutes)]
1295    #[ferrocene::prevalidated]
1296    pub const fn from_bits(v: u32) -> Self {
1297        // It turns out the safety issues with sNaN were overblown! Hooray!
1298        // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1299        unsafe { mem::transmute(v) }
1300    }
1301
1302    /// Returns the memory representation of this floating point number as a byte array in
1303    /// big-endian (network) byte order.
1304    ///
1305    /// See [`from_bits`](Self::from_bits) for some discussion of the
1306    /// portability of this operation (there are almost no issues).
1307    ///
1308    /// # Examples
1309    ///
1310    /// ```
1311    /// let bytes = 12.5f32.to_be_bytes();
1312    /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1313    /// ```
1314    #[must_use = "this returns the result of the operation, \
1315                  without modifying the original"]
1316    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1317    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1318    #[inline]
1319    pub const fn to_be_bytes(self) -> [u8; 4] {
1320        self.to_bits().to_be_bytes()
1321    }
1322
1323    /// Returns the memory representation of this floating point number as a byte array in
1324    /// little-endian byte order.
1325    ///
1326    /// See [`from_bits`](Self::from_bits) for some discussion of the
1327    /// portability of this operation (there are almost no issues).
1328    ///
1329    /// # Examples
1330    ///
1331    /// ```
1332    /// let bytes = 12.5f32.to_le_bytes();
1333    /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1334    /// ```
1335    #[must_use = "this returns the result of the operation, \
1336                  without modifying the original"]
1337    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1338    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1339    #[inline]
1340    #[ferrocene::prevalidated]
1341    pub const fn to_le_bytes(self) -> [u8; 4] {
1342        self.to_bits().to_le_bytes()
1343    }
1344
1345    /// Returns the memory representation of this floating point number as a byte array in
1346    /// native byte order.
1347    ///
1348    /// As the target platform's native endianness is used, portable code
1349    /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1350    ///
1351    /// [`to_be_bytes`]: f32::to_be_bytes
1352    /// [`to_le_bytes`]: f32::to_le_bytes
1353    ///
1354    /// See [`from_bits`](Self::from_bits) for some discussion of the
1355    /// portability of this operation (there are almost no issues).
1356    ///
1357    /// # Examples
1358    ///
1359    /// ```
1360    /// let bytes = 12.5f32.to_ne_bytes();
1361    /// assert_eq!(
1362    ///     bytes,
1363    ///     if cfg!(target_endian = "big") {
1364    ///         [0x41, 0x48, 0x00, 0x00]
1365    ///     } else {
1366    ///         [0x00, 0x00, 0x48, 0x41]
1367    ///     }
1368    /// );
1369    /// ```
1370    #[must_use = "this returns the result of the operation, \
1371                  without modifying the original"]
1372    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1373    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1374    #[inline]
1375    pub const fn to_ne_bytes(self) -> [u8; 4] {
1376        self.to_bits().to_ne_bytes()
1377    }
1378
1379    /// Creates a floating point value from its representation as a byte array in big endian.
1380    ///
1381    /// See [`from_bits`](Self::from_bits) for some discussion of the
1382    /// portability of this operation (there are almost no issues).
1383    ///
1384    /// # Examples
1385    ///
1386    /// ```
1387    /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1388    /// assert_eq!(value, 12.5);
1389    /// ```
1390    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1391    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1392    #[must_use]
1393    #[inline]
1394    pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1395        Self::from_bits(u32::from_be_bytes(bytes))
1396    }
1397
1398    /// Creates a floating point value from its representation as a byte array in little endian.
1399    ///
1400    /// See [`from_bits`](Self::from_bits) for some discussion of the
1401    /// portability of this operation (there are almost no issues).
1402    ///
1403    /// # Examples
1404    ///
1405    /// ```
1406    /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1407    /// assert_eq!(value, 12.5);
1408    /// ```
1409    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1410    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1411    #[must_use]
1412    #[inline]
1413    #[ferrocene::prevalidated]
1414    pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1415        Self::from_bits(u32::from_le_bytes(bytes))
1416    }
1417
1418    /// Creates a floating point value from its representation as a byte array in native endian.
1419    ///
1420    /// As the target platform's native endianness is used, portable code
1421    /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1422    /// appropriate instead.
1423    ///
1424    /// [`from_be_bytes`]: f32::from_be_bytes
1425    /// [`from_le_bytes`]: f32::from_le_bytes
1426    ///
1427    /// See [`from_bits`](Self::from_bits) for some discussion of the
1428    /// portability of this operation (there are almost no issues).
1429    ///
1430    /// # Examples
1431    ///
1432    /// ```
1433    /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1434    ///     [0x41, 0x48, 0x00, 0x00]
1435    /// } else {
1436    ///     [0x00, 0x00, 0x48, 0x41]
1437    /// });
1438    /// assert_eq!(value, 12.5);
1439    /// ```
1440    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1441    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1442    #[must_use]
1443    #[inline]
1444    pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1445        Self::from_bits(u32::from_ne_bytes(bytes))
1446    }
1447
1448    /// Returns the ordering between `self` and `other`.
1449    ///
1450    /// Unlike the standard partial comparison between floating point numbers,
1451    /// this comparison always produces an ordering in accordance to
1452    /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1453    /// floating point standard. The values are ordered in the following sequence:
1454    ///
1455    /// - negative quiet NaN
1456    /// - negative signaling NaN
1457    /// - negative infinity
1458    /// - negative numbers
1459    /// - negative subnormal numbers
1460    /// - negative zero
1461    /// - positive zero
1462    /// - positive subnormal numbers
1463    /// - positive numbers
1464    /// - positive infinity
1465    /// - positive signaling NaN
1466    /// - positive quiet NaN.
1467    ///
1468    /// The ordering established by this function does not always agree with the
1469    /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1470    /// they consider negative and positive zero equal, while `total_cmp`
1471    /// doesn't.
1472    ///
1473    /// The interpretation of the signaling NaN bit follows the definition in
1474    /// the IEEE 754 standard, which may not match the interpretation by some of
1475    /// the older, non-conformant (e.g. MIPS) hardware implementations.
1476    ///
1477    /// # Example
1478    ///
1479    /// ```
1480    /// struct GoodBoy {
1481    ///     name: String,
1482    ///     weight: f32,
1483    /// }
1484    ///
1485    /// let mut bois = vec![
1486    ///     GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1487    ///     GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1488    ///     GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1489    ///     GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1490    ///     GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1491    ///     GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1492    /// ];
1493    ///
1494    /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1495    ///
1496    /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1497    /// if f32::NAN.is_sign_negative() {
1498    ///     assert!(bois.into_iter().map(|b| b.weight)
1499    ///         .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1500    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1501    /// } else {
1502    ///     assert!(bois.into_iter().map(|b| b.weight)
1503    ///         .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1504    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1505    /// }
1506    /// ```
1507    #[stable(feature = "total_cmp", since = "1.62.0")]
1508    #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1509    #[must_use]
1510    #[inline]
1511    pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1512        let mut left = self.to_bits() as i32;
1513        let mut right = other.to_bits() as i32;
1514
1515        // In case of negatives, flip all the bits except the sign
1516        // to achieve a similar layout as two's complement integers
1517        //
1518        // Why does this work? IEEE 754 floats consist of three fields:
1519        // Sign bit, exponent and mantissa. The set of exponent and mantissa
1520        // fields as a whole have the property that their bitwise order is
1521        // equal to the numeric magnitude where the magnitude is defined.
1522        // The magnitude is not normally defined on NaN values, but
1523        // IEEE 754 totalOrder defines the NaN values also to follow the
1524        // bitwise order. This leads to order explained in the doc comment.
1525        // However, the representation of magnitude is the same for negative
1526        // and positive numbers – only the sign bit is different.
1527        // To easily compare the floats as signed integers, we need to
1528        // flip the exponent and mantissa bits in case of negative numbers.
1529        // We effectively convert the numbers to "two's complement" form.
1530        //
1531        // To do the flipping, we construct a mask and XOR against it.
1532        // We branchlessly calculate an "all-ones except for the sign bit"
1533        // mask from negative-signed values: right shifting sign-extends
1534        // the integer, so we "fill" the mask with sign bits, and then
1535        // convert to unsigned to push one more zero bit.
1536        // On positive values, the mask is all zeros, so it's a no-op.
1537        left ^= (((left >> 31) as u32) >> 1) as i32;
1538        right ^= (((right >> 31) as u32) >> 1) as i32;
1539
1540        left.cmp(&right)
1541    }
1542
1543    /// Restrict a value to a certain interval unless it is NaN.
1544    ///
1545    /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1546    /// less than `min`. Otherwise this returns `self`.
1547    ///
1548    /// Note that this function returns NaN if the initial value was NaN as
1549    /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1550    /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1551    ///
1552    /// # Panics
1553    ///
1554    /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1555    ///
1556    /// # Examples
1557    ///
1558    /// ```
1559    /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1560    /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1561    /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1562    /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1563    ///
1564    /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1565    /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1566    /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1567    /// // This is definitely a negative zero.
1568    /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1569    /// ```
1570    #[must_use = "method returns a new number and does not mutate the original value"]
1571    #[stable(feature = "clamp", since = "1.50.0")]
1572    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1573    #[inline]
1574    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1575        const_assert!(
1576            min <= max,
1577            "min > max, or either was NaN",
1578            "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1579            min: f32,
1580            max: f32,
1581        );
1582
1583        if self < min {
1584            self = min;
1585        }
1586        if self > max {
1587            self = max;
1588        }
1589        self
1590    }
1591
1592    /// Clamps this number to a symmetric range centered around zero.
1593    ///
1594    /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1595    ///
1596    /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1597    /// explicit about the intent.
1598    ///
1599    /// # Panics
1600    ///
1601    /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1602    ///
1603    /// # Examples
1604    ///
1605    /// ```
1606    /// #![feature(clamp_magnitude)]
1607    /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1608    /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1609    /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1610    /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1611    /// ```
1612    #[must_use = "this returns the clamped value and does not modify the original"]
1613    #[unstable(feature = "clamp_magnitude", issue = "148519")]
1614    #[inline]
1615    pub fn clamp_magnitude(self, limit: f32) -> f32 {
1616        assert!(limit >= 0.0, "limit must be non-negative");
1617        let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1618        self.clamp(-limit, limit)
1619    }
1620
1621    /// Computes the absolute value of `self`.
1622    ///
1623    /// This function always returns the precise result.
1624    ///
1625    /// # Examples
1626    ///
1627    /// ```
1628    /// let x = 3.5_f32;
1629    /// let y = -3.5_f32;
1630    ///
1631    /// assert_eq!(x.abs(), x);
1632    /// assert_eq!(y.abs(), -y);
1633    ///
1634    /// assert!(f32::NAN.abs().is_nan());
1635    /// ```
1636    #[must_use = "method returns a new number and does not mutate the original value"]
1637    #[stable(feature = "rust1", since = "1.0.0")]
1638    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1639    #[inline]
1640    #[ferrocene::prevalidated]
1641    pub const fn abs(self) -> f32 {
1642        intrinsics::fabs(self)
1643    }
1644
1645    /// Returns a number that represents the sign of `self`.
1646    ///
1647    /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1648    /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1649    /// - NaN if the number is NaN
1650    ///
1651    /// # Examples
1652    ///
1653    /// ```
1654    /// let f = 3.5_f32;
1655    ///
1656    /// assert_eq!(f.signum(), 1.0);
1657    /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1658    ///
1659    /// assert!(f32::NAN.signum().is_nan());
1660    /// ```
1661    #[must_use = "method returns a new number and does not mutate the original value"]
1662    #[stable(feature = "rust1", since = "1.0.0")]
1663    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1664    #[inline]
1665    #[ferrocene::prevalidated]
1666    pub const fn signum(self) -> f32 {
1667        if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1668    }
1669
1670    /// Returns a number composed of the magnitude of `self` and the sign of
1671    /// `sign`.
1672    ///
1673    /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1674    /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1675    /// returned.
1676    ///
1677    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1678    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1679    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1680    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1681    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1682    /// info.
1683    ///
1684    /// # Examples
1685    ///
1686    /// ```
1687    /// let f = 3.5_f32;
1688    ///
1689    /// assert_eq!(f.copysign(0.42), 3.5_f32);
1690    /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1691    /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1692    /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1693    ///
1694    /// assert!(f32::NAN.copysign(1.0).is_nan());
1695    /// ```
1696    #[must_use = "method returns a new number and does not mutate the original value"]
1697    #[inline]
1698    #[stable(feature = "copysign", since = "1.35.0")]
1699    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1700    #[ferrocene::prevalidated]
1701    pub const fn copysign(self, sign: f32) -> f32 {
1702        intrinsics::copysignf32(self, sign)
1703    }
1704
1705    /// Float addition that allows optimizations based on algebraic rules.
1706    ///
1707    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1708    #[must_use = "method returns a new number and does not mutate the original value"]
1709    #[unstable(feature = "float_algebraic", issue = "136469")]
1710    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1711    #[inline]
1712    pub const fn algebraic_add(self, rhs: f32) -> f32 {
1713        intrinsics::fadd_algebraic(self, rhs)
1714    }
1715
1716    /// Float subtraction that allows optimizations based on algebraic rules.
1717    ///
1718    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1719    #[must_use = "method returns a new number and does not mutate the original value"]
1720    #[unstable(feature = "float_algebraic", issue = "136469")]
1721    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1722    #[inline]
1723    pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1724        intrinsics::fsub_algebraic(self, rhs)
1725    }
1726
1727    /// Float multiplication that allows optimizations based on algebraic rules.
1728    ///
1729    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1730    #[must_use = "method returns a new number and does not mutate the original value"]
1731    #[unstable(feature = "float_algebraic", issue = "136469")]
1732    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1733    #[inline]
1734    pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1735        intrinsics::fmul_algebraic(self, rhs)
1736    }
1737
1738    /// Float division that allows optimizations based on algebraic rules.
1739    ///
1740    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1741    #[must_use = "method returns a new number and does not mutate the original value"]
1742    #[unstable(feature = "float_algebraic", issue = "136469")]
1743    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1744    #[inline]
1745    pub const fn algebraic_div(self, rhs: f32) -> f32 {
1746        intrinsics::fdiv_algebraic(self, rhs)
1747    }
1748
1749    /// Float remainder that allows optimizations based on algebraic rules.
1750    ///
1751    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1752    #[must_use = "method returns a new number and does not mutate the original value"]
1753    #[unstable(feature = "float_algebraic", issue = "136469")]
1754    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1755    #[inline]
1756    pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1757        intrinsics::frem_algebraic(self, rhs)
1758    }
1759}
1760
1761/// Experimental implementations of floating point functions in `core`.
1762///
1763/// _The standalone functions in this module are for testing only.
1764/// They will be stabilized as inherent methods._
1765#[unstable(feature = "core_float_math", issue = "137578")]
1766pub mod math {
1767    use crate::intrinsics;
1768    use crate::num::imp::libm;
1769
1770    /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1771    ///
1772    /// # Examples
1773    ///
1774    /// ```
1775    /// #![feature(core_float_math)]
1776    ///
1777    /// use core::f32;
1778    ///
1779    /// let f = 3.7_f32;
1780    /// let g = 3.0_f32;
1781    /// let h = -3.7_f32;
1782    ///
1783    /// assert_eq!(f32::math::floor(f), 3.0);
1784    /// assert_eq!(f32::math::floor(g), 3.0);
1785    /// assert_eq!(f32::math::floor(h), -4.0);
1786    /// ```
1787    ///
1788    /// _This standalone function is for testing only.
1789    /// It will be stabilized as an inherent method._
1790    ///
1791    /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1792    #[inline]
1793    #[unstable(feature = "core_float_math", issue = "137578")]
1794    #[must_use = "method returns a new number and does not mutate the original value"]
1795    pub const fn floor(x: f32) -> f32 {
1796        intrinsics::floorf32(x)
1797    }
1798
1799    /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1800    ///
1801    /// # Examples
1802    ///
1803    /// ```
1804    /// #![feature(core_float_math)]
1805    ///
1806    /// use core::f32;
1807    ///
1808    /// let f = 3.01_f32;
1809    /// let g = 4.0_f32;
1810    ///
1811    /// assert_eq!(f32::math::ceil(f), 4.0);
1812    /// assert_eq!(f32::math::ceil(g), 4.0);
1813    /// ```
1814    ///
1815    /// _This standalone function is for testing only.
1816    /// It will be stabilized as an inherent method._
1817    ///
1818    /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1819    #[inline]
1820    #[doc(alias = "ceiling")]
1821    #[must_use = "method returns a new number and does not mutate the original value"]
1822    #[unstable(feature = "core_float_math", issue = "137578")]
1823    pub const fn ceil(x: f32) -> f32 {
1824        intrinsics::ceilf32(x)
1825    }
1826
1827    /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1828    ///
1829    /// # Examples
1830    ///
1831    /// ```
1832    /// #![feature(core_float_math)]
1833    ///
1834    /// use core::f32;
1835    ///
1836    /// let f = 3.3_f32;
1837    /// let g = -3.3_f32;
1838    /// let h = -3.7_f32;
1839    /// let i = 3.5_f32;
1840    /// let j = 4.5_f32;
1841    ///
1842    /// assert_eq!(f32::math::round(f), 3.0);
1843    /// assert_eq!(f32::math::round(g), -3.0);
1844    /// assert_eq!(f32::math::round(h), -4.0);
1845    /// assert_eq!(f32::math::round(i), 4.0);
1846    /// assert_eq!(f32::math::round(j), 5.0);
1847    /// ```
1848    ///
1849    /// _This standalone function is for testing only.
1850    /// It will be stabilized as an inherent method._
1851    ///
1852    /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
1853    #[inline]
1854    #[unstable(feature = "core_float_math", issue = "137578")]
1855    #[must_use = "method returns a new number and does not mutate the original value"]
1856    pub const fn round(x: f32) -> f32 {
1857        intrinsics::roundf32(x)
1858    }
1859
1860    /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
1861    /// details.
1862    ///
1863    /// # Examples
1864    ///
1865    /// ```
1866    /// #![feature(core_float_math)]
1867    ///
1868    /// use core::f32;
1869    ///
1870    /// let f = 3.3_f32;
1871    /// let g = -3.3_f32;
1872    /// let h = 3.5_f32;
1873    /// let i = 4.5_f32;
1874    ///
1875    /// assert_eq!(f32::math::round_ties_even(f), 3.0);
1876    /// assert_eq!(f32::math::round_ties_even(g), -3.0);
1877    /// assert_eq!(f32::math::round_ties_even(h), 4.0);
1878    /// assert_eq!(f32::math::round_ties_even(i), 4.0);
1879    /// ```
1880    ///
1881    /// _This standalone function is for testing only.
1882    /// It will be stabilized as an inherent method._
1883    ///
1884    /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
1885    #[inline]
1886    #[unstable(feature = "core_float_math", issue = "137578")]
1887    #[must_use = "method returns a new number and does not mutate the original value"]
1888    pub const fn round_ties_even(x: f32) -> f32 {
1889        intrinsics::round_ties_even_f32(x)
1890    }
1891
1892    /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
1893    ///
1894    /// # Examples
1895    ///
1896    /// ```
1897    /// #![feature(core_float_math)]
1898    ///
1899    /// use core::f32;
1900    ///
1901    /// let f = 3.7_f32;
1902    /// let g = 3.0_f32;
1903    /// let h = -3.7_f32;
1904    ///
1905    /// assert_eq!(f32::math::trunc(f), 3.0);
1906    /// assert_eq!(f32::math::trunc(g), 3.0);
1907    /// assert_eq!(f32::math::trunc(h), -3.0);
1908    /// ```
1909    ///
1910    /// _This standalone function is for testing only.
1911    /// It will be stabilized as an inherent method._
1912    ///
1913    /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
1914    #[inline]
1915    #[doc(alias = "truncate")]
1916    #[must_use = "method returns a new number and does not mutate the original value"]
1917    #[unstable(feature = "core_float_math", issue = "137578")]
1918    pub const fn trunc(x: f32) -> f32 {
1919        intrinsics::truncf32(x)
1920    }
1921
1922    /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
1923    ///
1924    /// # Examples
1925    ///
1926    /// ```
1927    /// #![feature(core_float_math)]
1928    ///
1929    /// use core::f32;
1930    ///
1931    /// let x = 3.6_f32;
1932    /// let y = -3.6_f32;
1933    /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
1934    /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
1935    ///
1936    /// assert!(abs_difference_x <= f32::EPSILON);
1937    /// assert!(abs_difference_y <= f32::EPSILON);
1938    /// ```
1939    ///
1940    /// _This standalone function is for testing only.
1941    /// It will be stabilized as an inherent method._
1942    ///
1943    /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
1944    #[inline]
1945    #[unstable(feature = "core_float_math", issue = "137578")]
1946    #[must_use = "method returns a new number and does not mutate the original value"]
1947    pub const fn fract(x: f32) -> f32 {
1948        x - trunc(x)
1949    }
1950
1951    /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
1952    ///
1953    /// # Examples
1954    ///
1955    /// ```
1956    /// # #![allow(unused_features)]
1957    /// #![feature(core_float_math)]
1958    ///
1959    /// # // FIXME(#140515): mingw has an incorrect fma
1960    /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
1961    /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
1962    /// use core::f32;
1963    ///
1964    /// let m = 10.0_f32;
1965    /// let x = 4.0_f32;
1966    /// let b = 60.0_f32;
1967    ///
1968    /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
1969    /// assert_eq!(m * x + b, 100.0);
1970    ///
1971    /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
1972    /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
1973    /// let minus_one = -1.0_f32;
1974    ///
1975    /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
1976    /// assert_eq!(
1977    ///     f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
1978    ///     -f32::EPSILON * f32::EPSILON
1979    /// );
1980    /// // Different rounding with the non-fused multiply and add.
1981    /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
1982    /// # }
1983    /// ```
1984    ///
1985    /// _This standalone function is for testing only.
1986    /// It will be stabilized as an inherent method._
1987    ///
1988    /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
1989    #[inline]
1990    #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
1991    #[must_use = "method returns a new number and does not mutate the original value"]
1992    #[unstable(feature = "core_float_math", issue = "137578")]
1993    pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
1994        intrinsics::fmaf32(x, y, z)
1995    }
1996
1997    /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
1998    ///
1999    /// # Examples
2000    ///
2001    /// ```
2002    /// #![feature(core_float_math)]
2003    ///
2004    /// use core::f32;
2005    ///
2006    /// let a: f32 = 7.0;
2007    /// let b = 4.0;
2008    /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
2009    /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
2010    /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
2011    /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
2012    /// ```
2013    ///
2014    /// _This standalone function is for testing only.
2015    /// It will be stabilized as an inherent method._
2016    ///
2017    /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
2018    #[inline]
2019    #[unstable(feature = "core_float_math", issue = "137578")]
2020    #[must_use = "method returns a new number and does not mutate the original value"]
2021    pub fn div_euclid(x: f32, rhs: f32) -> f32 {
2022        let q = trunc(x / rhs);
2023        if x % rhs < 0.0 {
2024            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
2025        }
2026        q
2027    }
2028
2029    /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
2030    ///
2031    /// # Examples
2032    ///
2033    /// ```
2034    /// #![feature(core_float_math)]
2035    ///
2036    /// use core::f32;
2037    ///
2038    /// let a: f32 = 7.0;
2039    /// let b = 4.0;
2040    /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
2041    /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
2042    /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
2043    /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
2044    /// // limitation due to round-off error
2045    /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
2046    /// ```
2047    ///
2048    /// _This standalone function is for testing only.
2049    /// It will be stabilized as an inherent method._
2050    ///
2051    /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
2052    #[inline]
2053    #[doc(alias = "modulo", alias = "mod")]
2054    #[unstable(feature = "core_float_math", issue = "137578")]
2055    #[must_use = "method returns a new number and does not mutate the original value"]
2056    pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
2057        let r = x % rhs;
2058        if r < 0.0 { r + rhs.abs() } else { r }
2059    }
2060
2061    /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
2062    ///
2063    /// # Examples
2064    ///
2065    /// ```
2066    /// #![feature(core_float_math)]
2067    ///
2068    /// use core::f32;
2069    ///
2070    /// let x = 2.0_f32;
2071    /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
2072    /// assert!(abs_difference <= 1e-5);
2073    ///
2074    /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
2075    /// ```
2076    ///
2077    /// _This standalone function is for testing only.
2078    /// It will be stabilized as an inherent method._
2079    ///
2080    /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
2081    #[inline]
2082    #[must_use = "method returns a new number and does not mutate the original value"]
2083    #[unstable(feature = "core_float_math", issue = "137578")]
2084    pub fn powi(x: f32, n: i32) -> f32 {
2085        intrinsics::powif32(x, n)
2086    }
2087
2088    /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
2089    ///
2090    /// # Examples
2091    ///
2092    /// ```
2093    /// #![feature(core_float_math)]
2094    ///
2095    /// use core::f32;
2096    ///
2097    /// let positive = 4.0_f32;
2098    /// let negative = -4.0_f32;
2099    /// let negative_zero = -0.0_f32;
2100    ///
2101    /// assert_eq!(f32::math::sqrt(positive), 2.0);
2102    /// assert!(f32::math::sqrt(negative).is_nan());
2103    /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
2104    /// ```
2105    ///
2106    /// _This standalone function is for testing only.
2107    /// It will be stabilized as an inherent method._
2108    ///
2109    /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
2110    #[inline]
2111    #[doc(alias = "squareRoot")]
2112    #[unstable(feature = "core_float_math", issue = "137578")]
2113    #[must_use = "method returns a new number and does not mutate the original value"]
2114    pub fn sqrt(x: f32) -> f32 {
2115        intrinsics::sqrtf32(x)
2116    }
2117
2118    /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
2119    ///
2120    /// # Examples
2121    ///
2122    /// ```
2123    /// #![feature(core_float_math)]
2124    ///
2125    /// use core::f32;
2126    ///
2127    /// let x = 3.0f32;
2128    /// let y = -3.0f32;
2129    ///
2130    /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
2131    /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
2132    ///
2133    /// assert!(abs_difference_x <= 1e-6);
2134    /// assert!(abs_difference_y <= 1e-6);
2135    /// ```
2136    ///
2137    /// _This standalone function is for testing only.
2138    /// It will be stabilized as an inherent method._
2139    ///
2140    /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
2141    #[inline]
2142    #[stable(feature = "rust1", since = "1.0.0")]
2143    #[deprecated(
2144        since = "1.10.0",
2145        note = "you probably meant `(self - other).abs()`: \
2146            this operation is `(self - other).max(0.0)` \
2147            except that `abs_sub` also propagates NaNs (also \
2148            known as `fdimf` in C). If you truly need the positive \
2149            difference, consider using that expression or the C function \
2150            `fdimf`, depending on how you wish to handle NaN (please consider \
2151            filing an issue describing your use-case too)."
2152    )]
2153    #[must_use = "method returns a new number and does not mutate the original value"]
2154    pub fn abs_sub(x: f32, other: f32) -> f32 {
2155        libm::fdimf(x, other)
2156    }
2157
2158    /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2159    ///
2160    /// # Unspecified precision
2161    ///
2162    /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2163    /// can even differ within the same execution from one invocation to the next.
2164    /// This function currently corresponds to the `cbrtf` from libc on Unix
2165    /// and Windows. Note that this might change in the future.
2166    ///
2167    /// # Examples
2168    ///
2169    /// ```
2170    /// #![feature(core_float_math)]
2171    ///
2172    /// use core::f32;
2173    ///
2174    /// let x = 8.0f32;
2175    ///
2176    /// // x^(1/3) - 2 == 0
2177    /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2178    ///
2179    /// assert!(abs_difference <= 1e-6);
2180    /// ```
2181    ///
2182    /// _This standalone function is for testing only.
2183    /// It will be stabilized as an inherent method._
2184    ///
2185    /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2186    #[inline]
2187    #[must_use = "method returns a new number and does not mutate the original value"]
2188    #[unstable(feature = "core_float_math", issue = "137578")]
2189    pub fn cbrt(x: f32) -> f32 {
2190        libm::cbrtf(x)
2191    }
2192}