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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
14#[cfg(not(feature = "ferrocene_subset"))]
15use crate::convert::FloatToInt;
16use crate::num::FpCategory;
17#[cfg(not(feature = "ferrocene_subset"))]
18use crate::panic::const_assert;
19#[cfg(not(feature = "ferrocene_subset"))]
20use crate::{cfg_select, intrinsics, mem};
21
22// Ferrocene addition: imports for certified subset
23#[cfg(feature = "ferrocene_subset")]
24#[rustfmt::skip]
25use crate::{intrinsics, mem};
26
27/// The radix or base of the internal representation of `f32`.
28/// Use [`f32::RADIX`] instead.
29///
30/// # Examples
31///
32/// ```rust
33/// // deprecated way
34/// # #[allow(deprecated, deprecated_in_future)]
35/// let r = std::f32::RADIX;
36///
37/// // intended way
38/// let r = f32::RADIX;
39/// ```
40#[stable(feature = "rust1", since = "1.0.0")]
41#[deprecated(since = "TBD", note = "replaced by the `RADIX` associated constant on `f32`")]
42#[rustc_diagnostic_item = "f32_legacy_const_radix"]
43pub const RADIX: u32 = f32::RADIX;
44
45/// Number of significant digits in base 2.
46/// Use [`f32::MANTISSA_DIGITS`] instead.
47///
48/// # Examples
49///
50/// ```rust
51/// // deprecated way
52/// # #[allow(deprecated, deprecated_in_future)]
53/// let d = std::f32::MANTISSA_DIGITS;
54///
55/// // intended way
56/// let d = f32::MANTISSA_DIGITS;
57/// ```
58#[stable(feature = "rust1", since = "1.0.0")]
59#[deprecated(
60    since = "TBD",
61    note = "replaced by the `MANTISSA_DIGITS` associated constant on `f32`"
62)]
63#[rustc_diagnostic_item = "f32_legacy_const_mantissa_dig"]
64pub const MANTISSA_DIGITS: u32 = f32::MANTISSA_DIGITS;
65
66/// Approximate number of significant digits in base 10.
67/// Use [`f32::DIGITS`] instead.
68///
69/// # Examples
70///
71/// ```rust
72/// // deprecated way
73/// # #[allow(deprecated, deprecated_in_future)]
74/// let d = std::f32::DIGITS;
75///
76/// // intended way
77/// let d = f32::DIGITS;
78/// ```
79#[stable(feature = "rust1", since = "1.0.0")]
80#[deprecated(since = "TBD", note = "replaced by the `DIGITS` associated constant on `f32`")]
81#[rustc_diagnostic_item = "f32_legacy_const_digits"]
82pub const DIGITS: u32 = f32::DIGITS;
83
84/// [Machine epsilon] value for `f32`.
85/// Use [`f32::EPSILON`] instead.
86///
87/// This is the difference between `1.0` and the next larger representable number.
88///
89/// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
90///
91/// # Examples
92///
93/// ```rust
94/// // deprecated way
95/// # #[allow(deprecated, deprecated_in_future)]
96/// let e = std::f32::EPSILON;
97///
98/// // intended way
99/// let e = f32::EPSILON;
100/// ```
101#[stable(feature = "rust1", since = "1.0.0")]
102#[deprecated(since = "TBD", note = "replaced by the `EPSILON` associated constant on `f32`")]
103#[rustc_diagnostic_item = "f32_legacy_const_epsilon"]
104pub const EPSILON: f32 = f32::EPSILON;
105
106/// Smallest finite `f32` value.
107/// Use [`f32::MIN`] instead.
108///
109/// # Examples
110///
111/// ```rust
112/// // deprecated way
113/// # #[allow(deprecated, deprecated_in_future)]
114/// let min = std::f32::MIN;
115///
116/// // intended way
117/// let min = f32::MIN;
118/// ```
119#[stable(feature = "rust1", since = "1.0.0")]
120#[deprecated(since = "TBD", note = "replaced by the `MIN` associated constant on `f32`")]
121#[rustc_diagnostic_item = "f32_legacy_const_min"]
122pub const MIN: f32 = f32::MIN;
123
124/// Smallest positive normal `f32` value.
125/// Use [`f32::MIN_POSITIVE`] instead.
126///
127/// # Examples
128///
129/// ```rust
130/// // deprecated way
131/// # #[allow(deprecated, deprecated_in_future)]
132/// let min = std::f32::MIN_POSITIVE;
133///
134/// // intended way
135/// let min = f32::MIN_POSITIVE;
136/// ```
137#[stable(feature = "rust1", since = "1.0.0")]
138#[deprecated(since = "TBD", note = "replaced by the `MIN_POSITIVE` associated constant on `f32`")]
139#[rustc_diagnostic_item = "f32_legacy_const_min_positive"]
140pub const MIN_POSITIVE: f32 = f32::MIN_POSITIVE;
141
142/// Largest finite `f32` value.
143/// Use [`f32::MAX`] instead.
144///
145/// # Examples
146///
147/// ```rust
148/// // deprecated way
149/// # #[allow(deprecated, deprecated_in_future)]
150/// let max = std::f32::MAX;
151///
152/// // intended way
153/// let max = f32::MAX;
154/// ```
155#[stable(feature = "rust1", since = "1.0.0")]
156#[deprecated(since = "TBD", note = "replaced by the `MAX` associated constant on `f32`")]
157#[rustc_diagnostic_item = "f32_legacy_const_max"]
158pub const MAX: f32 = f32::MAX;
159
160/// One greater than the minimum possible normal power of 2 exponent.
161/// Use [`f32::MIN_EXP`] instead.
162///
163/// # Examples
164///
165/// ```rust
166/// // deprecated way
167/// # #[allow(deprecated, deprecated_in_future)]
168/// let min = std::f32::MIN_EXP;
169///
170/// // intended way
171/// let min = f32::MIN_EXP;
172/// ```
173#[stable(feature = "rust1", since = "1.0.0")]
174#[deprecated(since = "TBD", note = "replaced by the `MIN_EXP` associated constant on `f32`")]
175#[rustc_diagnostic_item = "f32_legacy_const_min_exp"]
176pub const MIN_EXP: i32 = f32::MIN_EXP;
177
178/// Maximum possible power of 2 exponent.
179/// Use [`f32::MAX_EXP`] instead.
180///
181/// # Examples
182///
183/// ```rust
184/// // deprecated way
185/// # #[allow(deprecated, deprecated_in_future)]
186/// let max = std::f32::MAX_EXP;
187///
188/// // intended way
189/// let max = f32::MAX_EXP;
190/// ```
191#[stable(feature = "rust1", since = "1.0.0")]
192#[deprecated(since = "TBD", note = "replaced by the `MAX_EXP` associated constant on `f32`")]
193#[rustc_diagnostic_item = "f32_legacy_const_max_exp"]
194pub const MAX_EXP: i32 = f32::MAX_EXP;
195
196/// Minimum possible normal power of 10 exponent.
197/// Use [`f32::MIN_10_EXP`] instead.
198///
199/// # Examples
200///
201/// ```rust
202/// // deprecated way
203/// # #[allow(deprecated, deprecated_in_future)]
204/// let min = std::f32::MIN_10_EXP;
205///
206/// // intended way
207/// let min = f32::MIN_10_EXP;
208/// ```
209#[stable(feature = "rust1", since = "1.0.0")]
210#[deprecated(since = "TBD", note = "replaced by the `MIN_10_EXP` associated constant on `f32`")]
211#[rustc_diagnostic_item = "f32_legacy_const_min_10_exp"]
212pub const MIN_10_EXP: i32 = f32::MIN_10_EXP;
213
214/// Maximum possible power of 10 exponent.
215/// Use [`f32::MAX_10_EXP`] instead.
216///
217/// # Examples
218///
219/// ```rust
220/// // deprecated way
221/// # #[allow(deprecated, deprecated_in_future)]
222/// let max = std::f32::MAX_10_EXP;
223///
224/// // intended way
225/// let max = f32::MAX_10_EXP;
226/// ```
227#[stable(feature = "rust1", since = "1.0.0")]
228#[deprecated(since = "TBD", note = "replaced by the `MAX_10_EXP` associated constant on `f32`")]
229#[rustc_diagnostic_item = "f32_legacy_const_max_10_exp"]
230pub const MAX_10_EXP: i32 = f32::MAX_10_EXP;
231
232/// Not a Number (NaN).
233/// Use [`f32::NAN`] instead.
234///
235/// # Examples
236///
237/// ```rust
238/// // deprecated way
239/// # #[allow(deprecated, deprecated_in_future)]
240/// let nan = std::f32::NAN;
241///
242/// // intended way
243/// let nan = f32::NAN;
244/// ```
245#[stable(feature = "rust1", since = "1.0.0")]
246#[deprecated(since = "TBD", note = "replaced by the `NAN` associated constant on `f32`")]
247#[rustc_diagnostic_item = "f32_legacy_const_nan"]
248pub const NAN: f32 = f32::NAN;
249
250/// Infinity (∞).
251/// Use [`f32::INFINITY`] instead.
252///
253/// # Examples
254///
255/// ```rust
256/// // deprecated way
257/// # #[allow(deprecated, deprecated_in_future)]
258/// let inf = std::f32::INFINITY;
259///
260/// // intended way
261/// let inf = f32::INFINITY;
262/// ```
263#[stable(feature = "rust1", since = "1.0.0")]
264#[deprecated(since = "TBD", note = "replaced by the `INFINITY` associated constant on `f32`")]
265#[rustc_diagnostic_item = "f32_legacy_const_infinity"]
266pub const INFINITY: f32 = f32::INFINITY;
267
268/// Negative infinity (−∞).
269/// Use [`f32::NEG_INFINITY`] instead.
270///
271/// # Examples
272///
273/// ```rust
274/// // deprecated way
275/// # #[allow(deprecated, deprecated_in_future)]
276/// let ninf = std::f32::NEG_INFINITY;
277///
278/// // intended way
279/// let ninf = f32::NEG_INFINITY;
280/// ```
281#[stable(feature = "rust1", since = "1.0.0")]
282#[deprecated(since = "TBD", note = "replaced by the `NEG_INFINITY` associated constant on `f32`")]
283#[rustc_diagnostic_item = "f32_legacy_const_neg_infinity"]
284pub const NEG_INFINITY: f32 = f32::NEG_INFINITY;
285
286/// Basic mathematical constants.
287#[stable(feature = "rust1", since = "1.0.0")]
288#[rustc_diagnostic_item = "f32_consts_mod"]
289pub mod consts {
290    // FIXME: replace with mathematical constants from cmath.
291
292    /// Archimedes' constant (π)
293    #[stable(feature = "rust1", since = "1.0.0")]
294    pub const PI: f32 = 3.14159265358979323846264338327950288_f32;
295
296    /// The full circle constant (τ)
297    ///
298    /// Equal to 2π.
299    #[stable(feature = "tau_constant", since = "1.47.0")]
300    pub const TAU: f32 = 6.28318530717958647692528676655900577_f32;
301
302    /// The golden ratio (φ)
303    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
304    pub const GOLDEN_RATIO: f32 = 1.618033988749894848204586834365638118_f32;
305
306    /// The Euler-Mascheroni constant (γ)
307    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
308    pub const EULER_GAMMA: f32 = 0.577215664901532860606512090082402431_f32;
309
310    /// π/2
311    #[stable(feature = "rust1", since = "1.0.0")]
312    pub const FRAC_PI_2: f32 = 1.57079632679489661923132169163975144_f32;
313
314    /// π/3
315    #[stable(feature = "rust1", since = "1.0.0")]
316    pub const FRAC_PI_3: f32 = 1.04719755119659774615421446109316763_f32;
317
318    /// π/4
319    #[stable(feature = "rust1", since = "1.0.0")]
320    pub const FRAC_PI_4: f32 = 0.785398163397448309615660845819875721_f32;
321
322    /// π/6
323    #[stable(feature = "rust1", since = "1.0.0")]
324    pub const FRAC_PI_6: f32 = 0.52359877559829887307710723054658381_f32;
325
326    /// π/8
327    #[stable(feature = "rust1", since = "1.0.0")]
328    pub const FRAC_PI_8: f32 = 0.39269908169872415480783042290993786_f32;
329
330    /// 1/π
331    #[stable(feature = "rust1", since = "1.0.0")]
332    pub const FRAC_1_PI: f32 = 0.318309886183790671537767526745028724_f32;
333
334    /// 1/sqrt(π)
335    #[unstable(feature = "more_float_constants", issue = "146939")]
336    pub const FRAC_1_SQRT_PI: f32 = 0.564189583547756286948079451560772586_f32;
337
338    /// 1/sqrt(2π)
339    #[doc(alias = "FRAC_1_SQRT_TAU")]
340    #[unstable(feature = "more_float_constants", issue = "146939")]
341    pub const FRAC_1_SQRT_2PI: f32 = 0.398942280401432677939946059934381868_f32;
342
343    /// 2/π
344    #[stable(feature = "rust1", since = "1.0.0")]
345    pub const FRAC_2_PI: f32 = 0.636619772367581343075535053490057448_f32;
346
347    /// 2/sqrt(π)
348    #[stable(feature = "rust1", since = "1.0.0")]
349    pub const FRAC_2_SQRT_PI: f32 = 1.12837916709551257389615890312154517_f32;
350
351    /// sqrt(2)
352    #[stable(feature = "rust1", since = "1.0.0")]
353    pub const SQRT_2: f32 = 1.41421356237309504880168872420969808_f32;
354
355    /// 1/sqrt(2)
356    #[stable(feature = "rust1", since = "1.0.0")]
357    pub const FRAC_1_SQRT_2: f32 = 0.707106781186547524400844362104849039_f32;
358
359    /// sqrt(3)
360    #[unstable(feature = "more_float_constants", issue = "146939")]
361    pub const SQRT_3: f32 = 1.732050807568877293527446341505872367_f32;
362
363    /// 1/sqrt(3)
364    #[unstable(feature = "more_float_constants", issue = "146939")]
365    pub const FRAC_1_SQRT_3: f32 = 0.577350269189625764509148780501957456_f32;
366
367    /// sqrt(5)
368    #[unstable(feature = "more_float_constants", issue = "146939")]
369    pub const SQRT_5: f32 = 2.23606797749978969640917366873127623_f32;
370
371    /// 1/sqrt(5)
372    #[unstable(feature = "more_float_constants", issue = "146939")]
373    pub const FRAC_1_SQRT_5: f32 = 0.44721359549995793928183473374625524_f32;
374
375    /// Euler's number (e)
376    #[stable(feature = "rust1", since = "1.0.0")]
377    pub const E: f32 = 2.71828182845904523536028747135266250_f32;
378
379    /// log<sub>2</sub>(e)
380    #[stable(feature = "rust1", since = "1.0.0")]
381    pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
382
383    /// log<sub>2</sub>(10)
384    #[stable(feature = "extra_log_consts", since = "1.43.0")]
385    pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
386
387    /// log<sub>10</sub>(e)
388    #[stable(feature = "rust1", since = "1.0.0")]
389    pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
390
391    /// log<sub>10</sub>(2)
392    #[stable(feature = "extra_log_consts", since = "1.43.0")]
393    pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
394
395    /// ln(2)
396    #[stable(feature = "rust1", since = "1.0.0")]
397    pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
398
399    /// ln(10)
400    #[stable(feature = "rust1", since = "1.0.0")]
401    pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
402}
403
404impl f32 {
405    /// The radix or base of the internal representation of `f32`.
406    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
407    pub const RADIX: u32 = 2;
408
409    /// The size of this float type in bits.
410    #[unstable(feature = "float_bits_const", issue = "151073")]
411    pub const BITS: u32 = 32;
412
413    /// Number of significant digits in base 2.
414    ///
415    /// Note that the size of the mantissa in the bitwise representation is one
416    /// smaller than this since the leading 1 is not stored explicitly.
417    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
418    pub const MANTISSA_DIGITS: u32 = 24;
419
420    /// Approximate number of significant digits in base 10.
421    ///
422    /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
423    /// significant digits can be converted to `f32` and back without loss.
424    ///
425    /// Equal to floor(log<sub>10</sub>&nbsp;2<sup>[`MANTISSA_DIGITS`]&nbsp;&minus;&nbsp;1</sup>).
426    ///
427    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
428    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
429    pub const DIGITS: u32 = 6;
430
431    /// [Machine epsilon] value for `f32`.
432    ///
433    /// This is the difference between `1.0` and the next larger representable number.
434    ///
435    /// Equal to 2<sup>1&nbsp;&minus;&nbsp;[`MANTISSA_DIGITS`]</sup>.
436    ///
437    /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
438    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
439    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
440    #[rustc_diagnostic_item = "f32_epsilon"]
441    pub const EPSILON: f32 = 1.19209290e-07_f32;
442
443    /// Smallest finite `f32` value.
444    ///
445    /// Equal to &minus;[`MAX`].
446    ///
447    /// [`MAX`]: f32::MAX
448    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
449    pub const MIN: f32 = -3.40282347e+38_f32;
450    /// Smallest positive normal `f32` value.
451    ///
452    /// Equal to 2<sup>[`MIN_EXP`]&nbsp;&minus;&nbsp;1</sup>.
453    ///
454    /// [`MIN_EXP`]: f32::MIN_EXP
455    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
456    pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
457    /// Largest finite `f32` value.
458    ///
459    /// Equal to
460    /// (1&nbsp;&minus;&nbsp;2<sup>&minus;[`MANTISSA_DIGITS`]</sup>)&nbsp;2<sup>[`MAX_EXP`]</sup>.
461    ///
462    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
463    /// [`MAX_EXP`]: f32::MAX_EXP
464    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
465    pub const MAX: f32 = 3.40282347e+38_f32;
466
467    /// One greater than the minimum possible *normal* power of 2 exponent
468    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
469    ///
470    /// This corresponds to the exact minimum possible *normal* power of 2 exponent
471    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
472    /// In other words, all normal numbers representable by this type are
473    /// greater than or equal to 0.5&nbsp;×&nbsp;2<sup><i>MIN_EXP</i></sup>.
474    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
475    pub const MIN_EXP: i32 = -125;
476    /// One greater than the maximum possible power of 2 exponent
477    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
478    ///
479    /// This corresponds to the exact maximum possible power of 2 exponent
480    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
481    /// In other words, all numbers representable by this type are
482    /// strictly less than 2<sup><i>MAX_EXP</i></sup>.
483    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
484    pub const MAX_EXP: i32 = 128;
485
486    /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
487    ///
488    /// Equal to ceil(log<sub>10</sub>&nbsp;[`MIN_POSITIVE`]).
489    ///
490    /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
491    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
492    pub const MIN_10_EXP: i32 = -37;
493    /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
494    ///
495    /// Equal to floor(log<sub>10</sub>&nbsp;[`MAX`]).
496    ///
497    /// [`MAX`]: f32::MAX
498    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
499    pub const MAX_10_EXP: i32 = 38;
500
501    /// Not a Number (NaN).
502    ///
503    /// Note that IEEE 754 doesn't define just a single NaN value; a plethora of bit patterns are
504    /// considered to be NaN. Furthermore, the standard makes a difference between a "signaling" and
505    /// a "quiet" NaN, and allows inspecting its "payload" (the unspecified bits in the bit pattern)
506    /// and its sign. See the [specification of NaN bit patterns](f32#nan-bit-patterns) for more
507    /// info.
508    ///
509    /// This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions
510    /// that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is
511    /// guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary.
512    /// The concrete bit pattern may change across Rust versions and target platforms.
513    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
514    #[rustc_diagnostic_item = "f32_nan"]
515    #[allow(clippy::eq_op)]
516    pub const NAN: f32 = 0.0_f32 / 0.0_f32;
517    /// Infinity (∞).
518    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
519    pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
520    /// Negative infinity (−∞).
521    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
522    pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
523
524    /// Maximum integer that can be represented exactly in an [`f32`] value,
525    /// with no other integer converting to the same floating point value.
526    ///
527    /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
528    /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
529    /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
530    /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
531    /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
532    /// "one-to-one" mapping.
533    ///
534    /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
535    /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
536    /// ```
537    /// #![feature(float_exact_integer_constants)]
538    /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
539    /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
540    /// let max_exact_int = f32::MAX_EXACT_INTEGER;
541    /// assert_eq!(max_exact_int, max_exact_int as f32 as i32);
542    /// assert_eq!(max_exact_int + 1, (max_exact_int + 1) as f32 as i32);
543    /// assert_ne!(max_exact_int + 2, (max_exact_int + 2) as f32 as i32);
544    ///
545    /// // Beyond `f32::MAX_EXACT_INTEGER`, multiple integers can map to one float value
546    /// assert_eq!((max_exact_int + 1) as f32, (max_exact_int + 2) as f32);
547    /// # }
548    /// ```
549    #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
550    pub const MAX_EXACT_INTEGER: i32 = (1 << Self::MANTISSA_DIGITS) - 1;
551
552    /// Minimum integer that can be represented exactly in an [`f32`] value,
553    /// with no other integer converting to the same floating point value.
554    ///
555    /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
556    /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
557    /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
558    /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
559    /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
560    /// "one-to-one" mapping.
561    ///
562    /// This constant is equivalent to `-MAX_EXACT_INTEGER`.
563    ///
564    /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
565    /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
566    /// ```
567    /// #![feature(float_exact_integer_constants)]
568    /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
569    /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
570    /// let min_exact_int = f32::MIN_EXACT_INTEGER;
571    /// assert_eq!(min_exact_int, min_exact_int as f32 as i32);
572    /// assert_eq!(min_exact_int - 1, (min_exact_int - 1) as f32 as i32);
573    /// assert_ne!(min_exact_int - 2, (min_exact_int - 2) as f32 as i32);
574    ///
575    /// // Below `f32::MIN_EXACT_INTEGER`, multiple integers can map to one float value
576    /// assert_eq!((min_exact_int - 1) as f32, (min_exact_int - 2) as f32);
577    /// # }
578    /// ```
579    #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
580    pub const MIN_EXACT_INTEGER: i32 = -Self::MAX_EXACT_INTEGER;
581
582    /// Sign bit
583    #[cfg(not(feature = "ferrocene_subset"))]
584    pub(crate) const SIGN_MASK: u32 = 0x8000_0000;
585
586    /// Exponent mask
587    pub(crate) const EXP_MASK: u32 = 0x7f80_0000;
588
589    /// Mantissa mask
590    pub(crate) const MAN_MASK: u32 = 0x007f_ffff;
591
592    /// Minimum representable positive value (min subnormal)
593    #[cfg(not(feature = "ferrocene_subset"))]
594    const TINY_BITS: u32 = 0x1;
595
596    /// Minimum representable negative value (min negative subnormal)
597    #[cfg(not(feature = "ferrocene_subset"))]
598    const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
599
600    /// Returns `true` if this value is NaN.
601    ///
602    /// ```
603    /// let nan = f32::NAN;
604    /// let f = 7.0_f32;
605    ///
606    /// assert!(nan.is_nan());
607    /// assert!(!f.is_nan());
608    /// ```
609    #[must_use]
610    #[stable(feature = "rust1", since = "1.0.0")]
611    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
612    #[inline]
613    #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
614    pub const fn is_nan(self) -> bool {
615        self != self
616    }
617
618    /// Returns `true` if this value is positive infinity or negative infinity, and
619    /// `false` otherwise.
620    ///
621    /// ```
622    /// let f = 7.0f32;
623    /// let inf = f32::INFINITY;
624    /// let neg_inf = f32::NEG_INFINITY;
625    /// let nan = f32::NAN;
626    ///
627    /// assert!(!f.is_infinite());
628    /// assert!(!nan.is_infinite());
629    ///
630    /// assert!(inf.is_infinite());
631    /// assert!(neg_inf.is_infinite());
632    /// ```
633    #[must_use]
634    #[stable(feature = "rust1", since = "1.0.0")]
635    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
636    #[inline]
637    pub const fn is_infinite(self) -> bool {
638        // Getting clever with transmutation can result in incorrect answers on some FPUs
639        // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
640        // See https://github.com/rust-lang/rust/issues/72327
641        (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
642    }
643
644    /// Returns `true` if this number is neither infinite nor NaN.
645    ///
646    /// ```
647    /// let f = 7.0f32;
648    /// let inf = f32::INFINITY;
649    /// let neg_inf = f32::NEG_INFINITY;
650    /// let nan = f32::NAN;
651    ///
652    /// assert!(f.is_finite());
653    ///
654    /// assert!(!nan.is_finite());
655    /// assert!(!inf.is_finite());
656    /// assert!(!neg_inf.is_finite());
657    /// ```
658    #[must_use]
659    #[stable(feature = "rust1", since = "1.0.0")]
660    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
661    #[inline]
662    #[cfg(not(feature = "ferrocene_subset"))]
663    pub const fn is_finite(self) -> bool {
664        // There's no need to handle NaN separately: if self is NaN,
665        // the comparison is not true, exactly as desired.
666        self.abs() < Self::INFINITY
667    }
668
669    /// Returns `true` if the number is [subnormal].
670    ///
671    /// ```
672    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
673    /// let max = f32::MAX;
674    /// let lower_than_min = 1.0e-40_f32;
675    /// let zero = 0.0_f32;
676    ///
677    /// assert!(!min.is_subnormal());
678    /// assert!(!max.is_subnormal());
679    ///
680    /// assert!(!zero.is_subnormal());
681    /// assert!(!f32::NAN.is_subnormal());
682    /// assert!(!f32::INFINITY.is_subnormal());
683    /// // Values between `0` and `min` are Subnormal.
684    /// assert!(lower_than_min.is_subnormal());
685    /// ```
686    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
687    #[must_use]
688    #[stable(feature = "is_subnormal", since = "1.53.0")]
689    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
690    #[inline]
691    #[cfg(not(feature = "ferrocene_subset"))]
692    pub const fn is_subnormal(self) -> bool {
693        matches!(self.classify(), FpCategory::Subnormal)
694    }
695
696    /// Returns `true` if the number is neither zero, infinite,
697    /// [subnormal], or NaN.
698    ///
699    /// ```
700    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
701    /// let max = f32::MAX;
702    /// let lower_than_min = 1.0e-40_f32;
703    /// let zero = 0.0_f32;
704    ///
705    /// assert!(min.is_normal());
706    /// assert!(max.is_normal());
707    ///
708    /// assert!(!zero.is_normal());
709    /// assert!(!f32::NAN.is_normal());
710    /// assert!(!f32::INFINITY.is_normal());
711    /// // Values between `0` and `min` are Subnormal.
712    /// assert!(!lower_than_min.is_normal());
713    /// ```
714    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
715    #[must_use]
716    #[stable(feature = "rust1", since = "1.0.0")]
717    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
718    #[inline]
719    #[cfg(not(feature = "ferrocene_subset"))]
720    pub const fn is_normal(self) -> bool {
721        matches!(self.classify(), FpCategory::Normal)
722    }
723
724    /// Returns the floating point category of the number. If only one property
725    /// is going to be tested, it is generally faster to use the specific
726    /// predicate instead.
727    ///
728    /// ```
729    /// use std::num::FpCategory;
730    ///
731    /// let num = 12.4_f32;
732    /// let inf = f32::INFINITY;
733    ///
734    /// assert_eq!(num.classify(), FpCategory::Normal);
735    /// assert_eq!(inf.classify(), FpCategory::Infinite);
736    /// ```
737    #[stable(feature = "rust1", since = "1.0.0")]
738    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
739    pub const fn classify(self) -> FpCategory {
740        // We used to have complicated logic here that avoids the simple bit-based tests to work
741        // around buggy codegen for x87 targets (see
742        // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
743        // of our tests is able to find any difference between the complicated and the naive
744        // version, so now we are back to the naive version.
745        let b = self.to_bits();
746        match (b & Self::MAN_MASK, b & Self::EXP_MASK) {
747            (0, Self::EXP_MASK) => FpCategory::Infinite,
748            (_, Self::EXP_MASK) => FpCategory::Nan,
749            (0, 0) => FpCategory::Zero,
750            (_, 0) => FpCategory::Subnormal,
751            _ => FpCategory::Normal,
752        }
753    }
754
755    /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
756    /// positive sign bit and positive infinity.
757    ///
758    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
759    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
760    /// conserved over arithmetic operations, the result of `is_sign_positive` on
761    /// a NaN might produce an unexpected or non-portable result. See the [specification
762    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
763    /// if you need fully portable behavior (will return `false` for all NaNs).
764    ///
765    /// ```
766    /// let f = 7.0_f32;
767    /// let g = -7.0_f32;
768    ///
769    /// assert!(f.is_sign_positive());
770    /// assert!(!g.is_sign_positive());
771    /// ```
772    #[must_use]
773    #[stable(feature = "rust1", since = "1.0.0")]
774    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
775    #[inline]
776    #[cfg(not(feature = "ferrocene_subset"))]
777    pub const fn is_sign_positive(self) -> bool {
778        !self.is_sign_negative()
779    }
780
781    /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
782    /// negative sign bit and negative infinity.
783    ///
784    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
785    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
786    /// conserved over arithmetic operations, the result of `is_sign_negative` on
787    /// a NaN might produce an unexpected or non-portable result. See the [specification
788    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
789    /// if you need fully portable behavior (will return `false` for all NaNs).
790    ///
791    /// ```
792    /// let f = 7.0f32;
793    /// let g = -7.0f32;
794    ///
795    /// assert!(!f.is_sign_negative());
796    /// assert!(g.is_sign_negative());
797    /// ```
798    #[must_use]
799    #[stable(feature = "rust1", since = "1.0.0")]
800    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
801    #[inline]
802    pub const fn is_sign_negative(self) -> bool {
803        // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
804        // applies to zeros and NaNs as well.
805        self.to_bits() & 0x8000_0000 != 0
806    }
807
808    /// Returns the least number greater than `self`.
809    ///
810    /// Let `TINY` be the smallest representable positive `f32`. Then,
811    ///  - if `self.is_nan()`, this returns `self`;
812    ///  - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
813    ///  - if `self` is `-TINY`, this returns -0.0;
814    ///  - if `self` is -0.0 or +0.0, this returns `TINY`;
815    ///  - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
816    ///  - otherwise the unique least value greater than `self` is returned.
817    ///
818    /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
819    /// is finite `x == x.next_up().next_down()` also holds.
820    ///
821    /// ```rust
822    /// // f32::EPSILON is the difference between 1.0 and the next number up.
823    /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
824    /// // But not for most numbers.
825    /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
826    /// assert_eq!(16777216f32.next_up(), 16777218.0);
827    /// ```
828    ///
829    /// This operation corresponds to IEEE-754 `nextUp`.
830    ///
831    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
832    /// [`INFINITY`]: Self::INFINITY
833    /// [`MIN`]: Self::MIN
834    /// [`MAX`]: Self::MAX
835    #[inline]
836    #[doc(alias = "nextUp")]
837    #[stable(feature = "float_next_up_down", since = "1.86.0")]
838    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
839    #[cfg(not(feature = "ferrocene_subset"))]
840    pub const fn next_up(self) -> Self {
841        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
842        // denormals to zero. This is in general unsound and unsupported, but here
843        // we do our best to still produce the correct result on such targets.
844        let bits = self.to_bits();
845        if self.is_nan() || bits == Self::INFINITY.to_bits() {
846            return self;
847        }
848
849        let abs = bits & !Self::SIGN_MASK;
850        let next_bits = if abs == 0 {
851            Self::TINY_BITS
852        } else if bits == abs {
853            bits + 1
854        } else {
855            bits - 1
856        };
857        Self::from_bits(next_bits)
858    }
859
860    /// Returns the greatest number less than `self`.
861    ///
862    /// Let `TINY` be the smallest representable positive `f32`. Then,
863    ///  - if `self.is_nan()`, this returns `self`;
864    ///  - if `self` is [`INFINITY`], this returns [`MAX`];
865    ///  - if `self` is `TINY`, this returns 0.0;
866    ///  - if `self` is -0.0 or +0.0, this returns `-TINY`;
867    ///  - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
868    ///  - otherwise the unique greatest value less than `self` is returned.
869    ///
870    /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
871    /// is finite `x == x.next_down().next_up()` also holds.
872    ///
873    /// ```rust
874    /// let x = 1.0f32;
875    /// // Clamp value into range [0, 1).
876    /// let clamped = x.clamp(0.0, 1.0f32.next_down());
877    /// assert!(clamped < 1.0);
878    /// assert_eq!(clamped.next_up(), 1.0);
879    /// ```
880    ///
881    /// This operation corresponds to IEEE-754 `nextDown`.
882    ///
883    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
884    /// [`INFINITY`]: Self::INFINITY
885    /// [`MIN`]: Self::MIN
886    /// [`MAX`]: Self::MAX
887    #[inline]
888    #[doc(alias = "nextDown")]
889    #[stable(feature = "float_next_up_down", since = "1.86.0")]
890    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
891    #[cfg(not(feature = "ferrocene_subset"))]
892    pub const fn next_down(self) -> Self {
893        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
894        // denormals to zero. This is in general unsound and unsupported, but here
895        // we do our best to still produce the correct result on such targets.
896        let bits = self.to_bits();
897        if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
898            return self;
899        }
900
901        let abs = bits & !Self::SIGN_MASK;
902        let next_bits = if abs == 0 {
903            Self::NEG_TINY_BITS
904        } else if bits == abs {
905            bits - 1
906        } else {
907            bits + 1
908        };
909        Self::from_bits(next_bits)
910    }
911
912    /// Takes the reciprocal (inverse) of a number, `1/x`.
913    ///
914    /// ```
915    /// let x = 2.0_f32;
916    /// let abs_difference = (x.recip() - (1.0 / x)).abs();
917    ///
918    /// assert!(abs_difference <= f32::EPSILON);
919    /// ```
920    #[must_use = "this returns the result of the operation, without modifying the original"]
921    #[stable(feature = "rust1", since = "1.0.0")]
922    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
923    #[inline]
924    #[cfg(not(feature = "ferrocene_subset"))]
925    pub const fn recip(self) -> f32 {
926        1.0 / self
927    }
928
929    /// Converts radians to degrees.
930    ///
931    /// # Unspecified precision
932    ///
933    /// The precision of this function is non-deterministic. This means it varies by platform,
934    /// Rust version, and can even differ within the same execution from one invocation to the next.
935    ///
936    /// # Examples
937    ///
938    /// ```
939    /// let angle = std::f32::consts::PI;
940    ///
941    /// let abs_difference = (angle.to_degrees() - 180.0).abs();
942    /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
943    /// assert!(abs_difference <= f32::EPSILON);
944    /// ```
945    #[must_use = "this returns the result of the operation, \
946                  without modifying the original"]
947    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
948    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
949    #[inline]
950    #[cfg(not(feature = "ferrocene_subset"))]
951    pub const fn to_degrees(self) -> f32 {
952        // Use a literal to avoid double rounding, consts::PI is already rounded,
953        // and dividing would round again.
954        const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
955        self * PIS_IN_180
956    }
957
958    /// Converts degrees to radians.
959    ///
960    /// # Unspecified precision
961    ///
962    /// The precision of this function is non-deterministic. This means it varies by platform,
963    /// Rust version, and can even differ within the same execution from one invocation to the next.
964    ///
965    /// # Examples
966    ///
967    /// ```
968    /// let angle = 180.0f32;
969    ///
970    /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
971    ///
972    /// assert!(abs_difference <= f32::EPSILON);
973    /// ```
974    #[must_use = "this returns the result of the operation, \
975                  without modifying the original"]
976    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
977    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
978    #[inline]
979    #[cfg(not(feature = "ferrocene_subset"))]
980    pub const fn to_radians(self) -> f32 {
981        // The division here is correctly rounded with respect to the true value of π/180.
982        // Although π is irrational and already rounded, the double rounding happens
983        // to produce correct result for f32.
984        const RADS_PER_DEG: f32 = consts::PI / 180.0;
985        self * RADS_PER_DEG
986    }
987
988    /// Returns the maximum of the two numbers, ignoring NaN.
989    ///
990    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
991    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
992    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
993    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
994    /// non-deterministically.
995    ///
996    /// The handling of NaNs follows the IEEE 754-2019 semantics for `maximumNumber`, treating all
997    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
998    /// follows the IEEE 754-2008 semantics for `maxNum`.
999    ///
1000    /// ```
1001    /// let x = 1.0f32;
1002    /// let y = 2.0f32;
1003    ///
1004    /// assert_eq!(x.max(y), y);
1005    /// assert_eq!(x.max(f32::NAN), x);
1006    /// ```
1007    #[must_use = "this returns the result of the comparison, without modifying either input"]
1008    #[stable(feature = "rust1", since = "1.0.0")]
1009    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1010    #[inline]
1011    pub const fn max(self, other: f32) -> f32 {
1012        intrinsics::maxnumf32(self, other)
1013    }
1014
1015    /// Returns the minimum of the two numbers, ignoring NaN.
1016    ///
1017    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
1018    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1019    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1020    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1021    /// non-deterministically.
1022    ///
1023    /// The handling of NaNs follows the IEEE 754-2019 semantics for `minimumNumber`, treating all
1024    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1025    /// follows the IEEE 754-2008 semantics for `minNum`.
1026    ///
1027    /// ```
1028    /// let x = 1.0f32;
1029    /// let y = 2.0f32;
1030    ///
1031    /// assert_eq!(x.min(y), x);
1032    /// assert_eq!(x.min(f32::NAN), x);
1033    /// ```
1034    #[must_use = "this returns the result of the comparison, without modifying either input"]
1035    #[stable(feature = "rust1", since = "1.0.0")]
1036    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1037    #[inline]
1038    pub const fn min(self, other: f32) -> f32 {
1039        intrinsics::minnumf32(self, other)
1040    }
1041
1042    /// Returns the maximum of the two numbers, propagating NaN.
1043    ///
1044    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1045    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1046    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1047    /// non-NaN inputs.
1048    ///
1049    /// This is in contrast to [`f32::max`] which only returns NaN when *both* arguments are NaN,
1050    /// and which does not reliably order `-0.0` and `+0.0`.
1051    ///
1052    /// This follows the IEEE 754-2019 semantics for `maximum`.
1053    ///
1054    /// ```
1055    /// #![feature(float_minimum_maximum)]
1056    /// let x = 1.0f32;
1057    /// let y = 2.0f32;
1058    ///
1059    /// assert_eq!(x.maximum(y), y);
1060    /// assert!(x.maximum(f32::NAN).is_nan());
1061    /// ```
1062    #[must_use = "this returns the result of the comparison, without modifying either input"]
1063    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1064    #[inline]
1065    #[cfg(not(feature = "ferrocene_subset"))]
1066    pub const fn maximum(self, other: f32) -> f32 {
1067        intrinsics::maximumf32(self, other)
1068    }
1069
1070    /// Returns the minimum of the two numbers, propagating NaN.
1071    ///
1072    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1073    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1074    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1075    /// non-NaN inputs.
1076    ///
1077    /// This is in contrast to [`f32::min`] which only returns NaN when *both* arguments are NaN,
1078    /// and which does not reliably order `-0.0` and `+0.0`.
1079    ///
1080    /// This follows the IEEE 754-2019 semantics for `minimum`.
1081    ///
1082    /// ```
1083    /// #![feature(float_minimum_maximum)]
1084    /// let x = 1.0f32;
1085    /// let y = 2.0f32;
1086    ///
1087    /// assert_eq!(x.minimum(y), x);
1088    /// assert!(x.minimum(f32::NAN).is_nan());
1089    /// ```
1090    #[must_use = "this returns the result of the comparison, without modifying either input"]
1091    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1092    #[inline]
1093    #[cfg(not(feature = "ferrocene_subset"))]
1094    pub const fn minimum(self, other: f32) -> f32 {
1095        intrinsics::minimumf32(self, other)
1096    }
1097
1098    /// Calculates the midpoint (average) between `self` and `rhs`.
1099    ///
1100    /// This returns NaN when *either* argument is NaN or if a combination of
1101    /// +inf and -inf is provided as arguments.
1102    ///
1103    /// # Examples
1104    ///
1105    /// ```
1106    /// assert_eq!(1f32.midpoint(4.0), 2.5);
1107    /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1108    /// ```
1109    #[inline]
1110    #[doc(alias = "average")]
1111    #[stable(feature = "num_midpoint", since = "1.85.0")]
1112    #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1113    #[cfg(not(feature = "ferrocene_subset"))]
1114    pub const fn midpoint(self, other: f32) -> f32 {
1115        cfg_select! {
1116            // Allow faster implementation that have known good 64-bit float
1117            // implementations. Falling back to the branchy code on targets that don't
1118            // have 64-bit hardware floats or buggy implementations.
1119            // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1120            any(
1121                target_arch = "x86_64",
1122                target_arch = "aarch64",
1123                all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1124                all(target_arch = "loongarch64", target_feature = "d"),
1125                all(target_arch = "arm", target_feature = "vfp2"),
1126                target_arch = "wasm32",
1127                target_arch = "wasm64",
1128            ) => {
1129                ((self as f64 + other as f64) / 2.0) as f32
1130            }
1131            _ => {
1132                const HI: f32 = f32::MAX / 2.;
1133
1134                let (a, b) = (self, other);
1135                let abs_a = a.abs();
1136                let abs_b = b.abs();
1137
1138                if abs_a <= HI && abs_b <= HI {
1139                    // Overflow is impossible
1140                    (a + b) / 2.
1141                } else {
1142                    (a / 2.) + (b / 2.)
1143                }
1144            }
1145        }
1146    }
1147
1148    /// Rounds toward zero and converts to any primitive integer type,
1149    /// assuming that the value is finite and fits in that type.
1150    ///
1151    /// ```
1152    /// let value = 4.6_f32;
1153    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1154    /// assert_eq!(rounded, 4);
1155    ///
1156    /// let value = -128.9_f32;
1157    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1158    /// assert_eq!(rounded, i8::MIN);
1159    /// ```
1160    ///
1161    /// # Safety
1162    ///
1163    /// The value must:
1164    ///
1165    /// * Not be `NaN`
1166    /// * Not be infinite
1167    /// * Be representable in the return type `Int`, after truncating off its fractional part
1168    #[must_use = "this returns the result of the operation, \
1169                  without modifying the original"]
1170    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1171    #[inline]
1172    #[cfg(not(feature = "ferrocene_subset"))]
1173    pub unsafe fn to_int_unchecked<Int>(self) -> Int
1174    where
1175        Self: FloatToInt<Int>,
1176    {
1177        // SAFETY: the caller must uphold the safety contract for
1178        // `FloatToInt::to_int_unchecked`.
1179        unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1180    }
1181
1182    /// Raw transmutation to `u32`.
1183    ///
1184    /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1185    ///
1186    /// See [`from_bits`](Self::from_bits) for some discussion of the
1187    /// portability of this operation (there are almost no issues).
1188    ///
1189    /// Note that this function is distinct from `as` casting, which attempts to
1190    /// preserve the *numeric* value, and not the bitwise value.
1191    ///
1192    /// # Examples
1193    ///
1194    /// ```
1195    /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1196    /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1197    ///
1198    /// ```
1199    #[must_use = "this returns the result of the operation, \
1200                  without modifying the original"]
1201    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1202    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1203    #[inline]
1204    #[allow(unnecessary_transmutes)]
1205    pub const fn to_bits(self) -> u32 {
1206        // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1207        unsafe { mem::transmute(self) }
1208    }
1209
1210    /// Raw transmutation from `u32`.
1211    ///
1212    /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1213    /// It turns out this is incredibly portable, for two reasons:
1214    ///
1215    /// * Floats and Ints have the same endianness on all supported platforms.
1216    /// * IEEE 754 very precisely specifies the bit layout of floats.
1217    ///
1218    /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1219    /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1220    /// (notably x86 and ARM) picked the interpretation that was ultimately
1221    /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1222    /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1223    ///
1224    /// Rather than trying to preserve signaling-ness cross-platform, this
1225    /// implementation favors preserving the exact bits. This means that
1226    /// any payloads encoded in NaNs will be preserved even if the result of
1227    /// this method is sent over the network from an x86 machine to a MIPS one.
1228    ///
1229    /// If the results of this method are only manipulated by the same
1230    /// architecture that produced them, then there is no portability concern.
1231    ///
1232    /// If the input isn't NaN, then there is no portability concern.
1233    ///
1234    /// If you don't care about signalingness (very likely), then there is no
1235    /// portability concern.
1236    ///
1237    /// Note that this function is distinct from `as` casting, which attempts to
1238    /// preserve the *numeric* value, and not the bitwise value.
1239    ///
1240    /// # Examples
1241    ///
1242    /// ```
1243    /// let v = f32::from_bits(0x41480000);
1244    /// assert_eq!(v, 12.5);
1245    /// ```
1246    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1247    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1248    #[must_use]
1249    #[inline]
1250    #[allow(unnecessary_transmutes)]
1251    pub const fn from_bits(v: u32) -> Self {
1252        // It turns out the safety issues with sNaN were overblown! Hooray!
1253        // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1254        unsafe { mem::transmute(v) }
1255    }
1256
1257    /// Returns the memory representation of this floating point number as a byte array in
1258    /// big-endian (network) byte order.
1259    ///
1260    /// See [`from_bits`](Self::from_bits) for some discussion of the
1261    /// portability of this operation (there are almost no issues).
1262    ///
1263    /// # Examples
1264    ///
1265    /// ```
1266    /// let bytes = 12.5f32.to_be_bytes();
1267    /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1268    /// ```
1269    #[must_use = "this returns the result of the operation, \
1270                  without modifying the original"]
1271    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1272    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1273    #[inline]
1274    #[cfg(not(feature = "ferrocene_subset"))]
1275    pub const fn to_be_bytes(self) -> [u8; 4] {
1276        self.to_bits().to_be_bytes()
1277    }
1278
1279    /// Returns the memory representation of this floating point number as a byte array in
1280    /// little-endian byte order.
1281    ///
1282    /// See [`from_bits`](Self::from_bits) for some discussion of the
1283    /// portability of this operation (there are almost no issues).
1284    ///
1285    /// # Examples
1286    ///
1287    /// ```
1288    /// let bytes = 12.5f32.to_le_bytes();
1289    /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1290    /// ```
1291    #[must_use = "this returns the result of the operation, \
1292                  without modifying the original"]
1293    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1294    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1295    #[inline]
1296    pub const fn to_le_bytes(self) -> [u8; 4] {
1297        self.to_bits().to_le_bytes()
1298    }
1299
1300    /// Returns the memory representation of this floating point number as a byte array in
1301    /// native byte order.
1302    ///
1303    /// As the target platform's native endianness is used, portable code
1304    /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1305    ///
1306    /// [`to_be_bytes`]: f32::to_be_bytes
1307    /// [`to_le_bytes`]: f32::to_le_bytes
1308    ///
1309    /// See [`from_bits`](Self::from_bits) for some discussion of the
1310    /// portability of this operation (there are almost no issues).
1311    ///
1312    /// # Examples
1313    ///
1314    /// ```
1315    /// let bytes = 12.5f32.to_ne_bytes();
1316    /// assert_eq!(
1317    ///     bytes,
1318    ///     if cfg!(target_endian = "big") {
1319    ///         [0x41, 0x48, 0x00, 0x00]
1320    ///     } else {
1321    ///         [0x00, 0x00, 0x48, 0x41]
1322    ///     }
1323    /// );
1324    /// ```
1325    #[must_use = "this returns the result of the operation, \
1326                  without modifying the original"]
1327    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1328    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1329    #[inline]
1330    #[cfg(not(feature = "ferrocene_subset"))]
1331    pub const fn to_ne_bytes(self) -> [u8; 4] {
1332        self.to_bits().to_ne_bytes()
1333    }
1334
1335    /// Creates a floating point value from its representation as a byte array in big endian.
1336    ///
1337    /// See [`from_bits`](Self::from_bits) for some discussion of the
1338    /// portability of this operation (there are almost no issues).
1339    ///
1340    /// # Examples
1341    ///
1342    /// ```
1343    /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1344    /// assert_eq!(value, 12.5);
1345    /// ```
1346    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1347    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1348    #[must_use]
1349    #[inline]
1350    #[cfg(not(feature = "ferrocene_subset"))]
1351    pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1352        Self::from_bits(u32::from_be_bytes(bytes))
1353    }
1354
1355    /// Creates a floating point value from its representation as a byte array in little endian.
1356    ///
1357    /// See [`from_bits`](Self::from_bits) for some discussion of the
1358    /// portability of this operation (there are almost no issues).
1359    ///
1360    /// # Examples
1361    ///
1362    /// ```
1363    /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1364    /// assert_eq!(value, 12.5);
1365    /// ```
1366    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1367    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1368    #[must_use]
1369    #[inline]
1370    pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1371        Self::from_bits(u32::from_le_bytes(bytes))
1372    }
1373
1374    /// Creates a floating point value from its representation as a byte array in native endian.
1375    ///
1376    /// As the target platform's native endianness is used, portable code
1377    /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1378    /// appropriate instead.
1379    ///
1380    /// [`from_be_bytes`]: f32::from_be_bytes
1381    /// [`from_le_bytes`]: f32::from_le_bytes
1382    ///
1383    /// See [`from_bits`](Self::from_bits) for some discussion of the
1384    /// portability of this operation (there are almost no issues).
1385    ///
1386    /// # Examples
1387    ///
1388    /// ```
1389    /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1390    ///     [0x41, 0x48, 0x00, 0x00]
1391    /// } else {
1392    ///     [0x00, 0x00, 0x48, 0x41]
1393    /// });
1394    /// assert_eq!(value, 12.5);
1395    /// ```
1396    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1397    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1398    #[must_use]
1399    #[inline]
1400    #[cfg(not(feature = "ferrocene_subset"))]
1401    pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1402        Self::from_bits(u32::from_ne_bytes(bytes))
1403    }
1404
1405    /// Returns the ordering between `self` and `other`.
1406    ///
1407    /// Unlike the standard partial comparison between floating point numbers,
1408    /// this comparison always produces an ordering in accordance to
1409    /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1410    /// floating point standard. The values are ordered in the following sequence:
1411    ///
1412    /// - negative quiet NaN
1413    /// - negative signaling NaN
1414    /// - negative infinity
1415    /// - negative numbers
1416    /// - negative subnormal numbers
1417    /// - negative zero
1418    /// - positive zero
1419    /// - positive subnormal numbers
1420    /// - positive numbers
1421    /// - positive infinity
1422    /// - positive signaling NaN
1423    /// - positive quiet NaN.
1424    ///
1425    /// The ordering established by this function does not always agree with the
1426    /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1427    /// they consider negative and positive zero equal, while `total_cmp`
1428    /// doesn't.
1429    ///
1430    /// The interpretation of the signaling NaN bit follows the definition in
1431    /// the IEEE 754 standard, which may not match the interpretation by some of
1432    /// the older, non-conformant (e.g. MIPS) hardware implementations.
1433    ///
1434    /// # Example
1435    ///
1436    /// ```
1437    /// struct GoodBoy {
1438    ///     name: String,
1439    ///     weight: f32,
1440    /// }
1441    ///
1442    /// let mut bois = vec![
1443    ///     GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1444    ///     GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1445    ///     GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1446    ///     GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1447    ///     GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1448    ///     GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1449    /// ];
1450    ///
1451    /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1452    ///
1453    /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1454    /// if f32::NAN.is_sign_negative() {
1455    ///     assert!(bois.into_iter().map(|b| b.weight)
1456    ///         .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1457    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1458    /// } else {
1459    ///     assert!(bois.into_iter().map(|b| b.weight)
1460    ///         .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1461    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1462    /// }
1463    /// ```
1464    #[stable(feature = "total_cmp", since = "1.62.0")]
1465    #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1466    #[must_use]
1467    #[inline]
1468    #[cfg(not(feature = "ferrocene_subset"))]
1469    pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1470        let mut left = self.to_bits() as i32;
1471        let mut right = other.to_bits() as i32;
1472
1473        // In case of negatives, flip all the bits except the sign
1474        // to achieve a similar layout as two's complement integers
1475        //
1476        // Why does this work? IEEE 754 floats consist of three fields:
1477        // Sign bit, exponent and mantissa. The set of exponent and mantissa
1478        // fields as a whole have the property that their bitwise order is
1479        // equal to the numeric magnitude where the magnitude is defined.
1480        // The magnitude is not normally defined on NaN values, but
1481        // IEEE 754 totalOrder defines the NaN values also to follow the
1482        // bitwise order. This leads to order explained in the doc comment.
1483        // However, the representation of magnitude is the same for negative
1484        // and positive numbers – only the sign bit is different.
1485        // To easily compare the floats as signed integers, we need to
1486        // flip the exponent and mantissa bits in case of negative numbers.
1487        // We effectively convert the numbers to "two's complement" form.
1488        //
1489        // To do the flipping, we construct a mask and XOR against it.
1490        // We branchlessly calculate an "all-ones except for the sign bit"
1491        // mask from negative-signed values: right shifting sign-extends
1492        // the integer, so we "fill" the mask with sign bits, and then
1493        // convert to unsigned to push one more zero bit.
1494        // On positive values, the mask is all zeros, so it's a no-op.
1495        left ^= (((left >> 31) as u32) >> 1) as i32;
1496        right ^= (((right >> 31) as u32) >> 1) as i32;
1497
1498        left.cmp(&right)
1499    }
1500
1501    /// Restrict a value to a certain interval unless it is NaN.
1502    ///
1503    /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1504    /// less than `min`. Otherwise this returns `self`.
1505    ///
1506    /// Note that this function returns NaN if the initial value was NaN as
1507    /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1508    /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1509    ///
1510    /// # Panics
1511    ///
1512    /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1513    ///
1514    /// # Examples
1515    ///
1516    /// ```
1517    /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1518    /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1519    /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1520    /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1521    ///
1522    /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1523    /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1524    /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1525    /// // This is definitely a negative zero.
1526    /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1527    /// ```
1528    #[must_use = "method returns a new number and does not mutate the original value"]
1529    #[stable(feature = "clamp", since = "1.50.0")]
1530    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1531    #[inline]
1532    #[cfg(not(feature = "ferrocene_subset"))]
1533    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1534        const_assert!(
1535            min <= max,
1536            "min > max, or either was NaN",
1537            "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1538            min: f32,
1539            max: f32,
1540        );
1541
1542        if self < min {
1543            self = min;
1544        }
1545        if self > max {
1546            self = max;
1547        }
1548        self
1549    }
1550
1551    /// Clamps this number to a symmetric range centered around zero.
1552    ///
1553    /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1554    ///
1555    /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1556    /// explicit about the intent.
1557    ///
1558    /// # Panics
1559    ///
1560    /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1561    ///
1562    /// # Examples
1563    ///
1564    /// ```
1565    /// #![feature(clamp_magnitude)]
1566    /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1567    /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1568    /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1569    /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1570    /// ```
1571    #[cfg(not(feature = "ferrocene_subset"))]
1572    #[must_use = "this returns the clamped value and does not modify the original"]
1573    #[unstable(feature = "clamp_magnitude", issue = "148519")]
1574    #[inline]
1575    pub fn clamp_magnitude(self, limit: f32) -> f32 {
1576        assert!(limit >= 0.0, "limit must be non-negative");
1577        let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1578        self.clamp(-limit, limit)
1579    }
1580
1581    /// Computes the absolute value of `self`.
1582    ///
1583    /// This function always returns the precise result.
1584    ///
1585    /// # Examples
1586    ///
1587    /// ```
1588    /// let x = 3.5_f32;
1589    /// let y = -3.5_f32;
1590    ///
1591    /// assert_eq!(x.abs(), x);
1592    /// assert_eq!(y.abs(), -y);
1593    ///
1594    /// assert!(f32::NAN.abs().is_nan());
1595    /// ```
1596    #[must_use = "method returns a new number and does not mutate the original value"]
1597    #[stable(feature = "rust1", since = "1.0.0")]
1598    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1599    #[inline]
1600    pub const fn abs(self) -> f32 {
1601        intrinsics::fabsf32(self)
1602    }
1603
1604    /// Returns a number that represents the sign of `self`.
1605    ///
1606    /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1607    /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1608    /// - NaN if the number is NaN
1609    ///
1610    /// # Examples
1611    ///
1612    /// ```
1613    /// let f = 3.5_f32;
1614    ///
1615    /// assert_eq!(f.signum(), 1.0);
1616    /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1617    ///
1618    /// assert!(f32::NAN.signum().is_nan());
1619    /// ```
1620    #[must_use = "method returns a new number and does not mutate the original value"]
1621    #[stable(feature = "rust1", since = "1.0.0")]
1622    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1623    #[inline]
1624    pub const fn signum(self) -> f32 {
1625        if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1626    }
1627
1628    /// Returns a number composed of the magnitude of `self` and the sign of
1629    /// `sign`.
1630    ///
1631    /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1632    /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1633    /// returned.
1634    ///
1635    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1636    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1637    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1638    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1639    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1640    /// info.
1641    ///
1642    /// # Examples
1643    ///
1644    /// ```
1645    /// let f = 3.5_f32;
1646    ///
1647    /// assert_eq!(f.copysign(0.42), 3.5_f32);
1648    /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1649    /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1650    /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1651    ///
1652    /// assert!(f32::NAN.copysign(1.0).is_nan());
1653    /// ```
1654    #[must_use = "method returns a new number and does not mutate the original value"]
1655    #[inline]
1656    #[stable(feature = "copysign", since = "1.35.0")]
1657    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1658    pub const fn copysign(self, sign: f32) -> f32 {
1659        intrinsics::copysignf32(self, sign)
1660    }
1661
1662    /// Float addition that allows optimizations based on algebraic rules.
1663    ///
1664    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1665    #[must_use = "method returns a new number and does not mutate the original value"]
1666    #[unstable(feature = "float_algebraic", issue = "136469")]
1667    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1668    #[inline]
1669    #[cfg(not(feature = "ferrocene_subset"))]
1670    pub const fn algebraic_add(self, rhs: f32) -> f32 {
1671        intrinsics::fadd_algebraic(self, rhs)
1672    }
1673
1674    /// Float subtraction that allows optimizations based on algebraic rules.
1675    ///
1676    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1677    #[must_use = "method returns a new number and does not mutate the original value"]
1678    #[unstable(feature = "float_algebraic", issue = "136469")]
1679    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1680    #[inline]
1681    #[cfg(not(feature = "ferrocene_subset"))]
1682    pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1683        intrinsics::fsub_algebraic(self, rhs)
1684    }
1685
1686    /// Float multiplication that allows optimizations based on algebraic rules.
1687    ///
1688    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1689    #[must_use = "method returns a new number and does not mutate the original value"]
1690    #[unstable(feature = "float_algebraic", issue = "136469")]
1691    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1692    #[inline]
1693    #[cfg(not(feature = "ferrocene_subset"))]
1694    pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1695        intrinsics::fmul_algebraic(self, rhs)
1696    }
1697
1698    /// Float division that allows optimizations based on algebraic rules.
1699    ///
1700    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1701    #[must_use = "method returns a new number and does not mutate the original value"]
1702    #[unstable(feature = "float_algebraic", issue = "136469")]
1703    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1704    #[inline]
1705    #[cfg(not(feature = "ferrocene_subset"))]
1706    pub const fn algebraic_div(self, rhs: f32) -> f32 {
1707        intrinsics::fdiv_algebraic(self, rhs)
1708    }
1709
1710    /// Float remainder that allows optimizations based on algebraic rules.
1711    ///
1712    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1713    #[must_use = "method returns a new number and does not mutate the original value"]
1714    #[unstable(feature = "float_algebraic", issue = "136469")]
1715    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1716    #[inline]
1717    #[cfg(not(feature = "ferrocene_subset"))]
1718    pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1719        intrinsics::frem_algebraic(self, rhs)
1720    }
1721}
1722
1723/// Experimental implementations of floating point functions in `core`.
1724///
1725/// _The standalone functions in this module are for testing only.
1726/// They will be stabilized as inherent methods._
1727#[unstable(feature = "core_float_math", issue = "137578")]
1728#[cfg(not(feature = "ferrocene_subset"))]
1729pub mod math {
1730    use crate::intrinsics;
1731    use crate::num::libm;
1732
1733    /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1734    ///
1735    /// # Examples
1736    ///
1737    /// ```
1738    /// #![feature(core_float_math)]
1739    ///
1740    /// use core::f32;
1741    ///
1742    /// let f = 3.7_f32;
1743    /// let g = 3.0_f32;
1744    /// let h = -3.7_f32;
1745    ///
1746    /// assert_eq!(f32::math::floor(f), 3.0);
1747    /// assert_eq!(f32::math::floor(g), 3.0);
1748    /// assert_eq!(f32::math::floor(h), -4.0);
1749    /// ```
1750    ///
1751    /// _This standalone function is for testing only.
1752    /// It will be stabilized as an inherent method._
1753    ///
1754    /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1755    #[inline]
1756    #[unstable(feature = "core_float_math", issue = "137578")]
1757    #[must_use = "method returns a new number and does not mutate the original value"]
1758    pub const fn floor(x: f32) -> f32 {
1759        intrinsics::floorf32(x)
1760    }
1761
1762    /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1763    ///
1764    /// # Examples
1765    ///
1766    /// ```
1767    /// #![feature(core_float_math)]
1768    ///
1769    /// use core::f32;
1770    ///
1771    /// let f = 3.01_f32;
1772    /// let g = 4.0_f32;
1773    ///
1774    /// assert_eq!(f32::math::ceil(f), 4.0);
1775    /// assert_eq!(f32::math::ceil(g), 4.0);
1776    /// ```
1777    ///
1778    /// _This standalone function is for testing only.
1779    /// It will be stabilized as an inherent method._
1780    ///
1781    /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1782    #[inline]
1783    #[doc(alias = "ceiling")]
1784    #[must_use = "method returns a new number and does not mutate the original value"]
1785    #[unstable(feature = "core_float_math", issue = "137578")]
1786    pub const fn ceil(x: f32) -> f32 {
1787        intrinsics::ceilf32(x)
1788    }
1789
1790    /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1791    ///
1792    /// # Examples
1793    ///
1794    /// ```
1795    /// #![feature(core_float_math)]
1796    ///
1797    /// use core::f32;
1798    ///
1799    /// let f = 3.3_f32;
1800    /// let g = -3.3_f32;
1801    /// let h = -3.7_f32;
1802    /// let i = 3.5_f32;
1803    /// let j = 4.5_f32;
1804    ///
1805    /// assert_eq!(f32::math::round(f), 3.0);
1806    /// assert_eq!(f32::math::round(g), -3.0);
1807    /// assert_eq!(f32::math::round(h), -4.0);
1808    /// assert_eq!(f32::math::round(i), 4.0);
1809    /// assert_eq!(f32::math::round(j), 5.0);
1810    /// ```
1811    ///
1812    /// _This standalone function is for testing only.
1813    /// It will be stabilized as an inherent method._
1814    ///
1815    /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
1816    #[inline]
1817    #[unstable(feature = "core_float_math", issue = "137578")]
1818    #[must_use = "method returns a new number and does not mutate the original value"]
1819    pub const fn round(x: f32) -> f32 {
1820        intrinsics::roundf32(x)
1821    }
1822
1823    /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
1824    /// details.
1825    ///
1826    /// # Examples
1827    ///
1828    /// ```
1829    /// #![feature(core_float_math)]
1830    ///
1831    /// use core::f32;
1832    ///
1833    /// let f = 3.3_f32;
1834    /// let g = -3.3_f32;
1835    /// let h = 3.5_f32;
1836    /// let i = 4.5_f32;
1837    ///
1838    /// assert_eq!(f32::math::round_ties_even(f), 3.0);
1839    /// assert_eq!(f32::math::round_ties_even(g), -3.0);
1840    /// assert_eq!(f32::math::round_ties_even(h), 4.0);
1841    /// assert_eq!(f32::math::round_ties_even(i), 4.0);
1842    /// ```
1843    ///
1844    /// _This standalone function is for testing only.
1845    /// It will be stabilized as an inherent method._
1846    ///
1847    /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
1848    #[inline]
1849    #[unstable(feature = "core_float_math", issue = "137578")]
1850    #[must_use = "method returns a new number and does not mutate the original value"]
1851    pub const fn round_ties_even(x: f32) -> f32 {
1852        intrinsics::round_ties_even_f32(x)
1853    }
1854
1855    /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
1856    ///
1857    /// # Examples
1858    ///
1859    /// ```
1860    /// #![feature(core_float_math)]
1861    ///
1862    /// use core::f32;
1863    ///
1864    /// let f = 3.7_f32;
1865    /// let g = 3.0_f32;
1866    /// let h = -3.7_f32;
1867    ///
1868    /// assert_eq!(f32::math::trunc(f), 3.0);
1869    /// assert_eq!(f32::math::trunc(g), 3.0);
1870    /// assert_eq!(f32::math::trunc(h), -3.0);
1871    /// ```
1872    ///
1873    /// _This standalone function is for testing only.
1874    /// It will be stabilized as an inherent method._
1875    ///
1876    /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
1877    #[inline]
1878    #[doc(alias = "truncate")]
1879    #[must_use = "method returns a new number and does not mutate the original value"]
1880    #[unstable(feature = "core_float_math", issue = "137578")]
1881    pub const fn trunc(x: f32) -> f32 {
1882        intrinsics::truncf32(x)
1883    }
1884
1885    /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
1886    ///
1887    /// # Examples
1888    ///
1889    /// ```
1890    /// #![feature(core_float_math)]
1891    ///
1892    /// use core::f32;
1893    ///
1894    /// let x = 3.6_f32;
1895    /// let y = -3.6_f32;
1896    /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
1897    /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
1898    ///
1899    /// assert!(abs_difference_x <= f32::EPSILON);
1900    /// assert!(abs_difference_y <= f32::EPSILON);
1901    /// ```
1902    ///
1903    /// _This standalone function is for testing only.
1904    /// It will be stabilized as an inherent method._
1905    ///
1906    /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
1907    #[inline]
1908    #[unstable(feature = "core_float_math", issue = "137578")]
1909    #[must_use = "method returns a new number and does not mutate the original value"]
1910    pub const fn fract(x: f32) -> f32 {
1911        x - trunc(x)
1912    }
1913
1914    /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
1915    ///
1916    /// # Examples
1917    ///
1918    /// ```
1919    /// # #![allow(unused_features)]
1920    /// #![feature(core_float_math)]
1921    ///
1922    /// # // FIXME(#140515): mingw has an incorrect fma
1923    /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
1924    /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
1925    /// use core::f32;
1926    ///
1927    /// let m = 10.0_f32;
1928    /// let x = 4.0_f32;
1929    /// let b = 60.0_f32;
1930    ///
1931    /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
1932    /// assert_eq!(m * x + b, 100.0);
1933    ///
1934    /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
1935    /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
1936    /// let minus_one = -1.0_f32;
1937    ///
1938    /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
1939    /// assert_eq!(
1940    ///     f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
1941    ///     -f32::EPSILON * f32::EPSILON
1942    /// );
1943    /// // Different rounding with the non-fused multiply and add.
1944    /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
1945    /// # }
1946    /// ```
1947    ///
1948    /// _This standalone function is for testing only.
1949    /// It will be stabilized as an inherent method._
1950    ///
1951    /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
1952    #[inline]
1953    #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
1954    #[must_use = "method returns a new number and does not mutate the original value"]
1955    #[unstable(feature = "core_float_math", issue = "137578")]
1956    pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
1957        intrinsics::fmaf32(x, y, z)
1958    }
1959
1960    /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
1961    ///
1962    /// # Examples
1963    ///
1964    /// ```
1965    /// #![feature(core_float_math)]
1966    ///
1967    /// use core::f32;
1968    ///
1969    /// let a: f32 = 7.0;
1970    /// let b = 4.0;
1971    /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
1972    /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
1973    /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
1974    /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
1975    /// ```
1976    ///
1977    /// _This standalone function is for testing only.
1978    /// It will be stabilized as an inherent method._
1979    ///
1980    /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
1981    #[inline]
1982    #[unstable(feature = "core_float_math", issue = "137578")]
1983    #[must_use = "method returns a new number and does not mutate the original value"]
1984    pub fn div_euclid(x: f32, rhs: f32) -> f32 {
1985        let q = trunc(x / rhs);
1986        if x % rhs < 0.0 {
1987            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
1988        }
1989        q
1990    }
1991
1992    /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
1993    ///
1994    /// # Examples
1995    ///
1996    /// ```
1997    /// #![feature(core_float_math)]
1998    ///
1999    /// use core::f32;
2000    ///
2001    /// let a: f32 = 7.0;
2002    /// let b = 4.0;
2003    /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
2004    /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
2005    /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
2006    /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
2007    /// // limitation due to round-off error
2008    /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
2009    /// ```
2010    ///
2011    /// _This standalone function is for testing only.
2012    /// It will be stabilized as an inherent method._
2013    ///
2014    /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
2015    #[inline]
2016    #[doc(alias = "modulo", alias = "mod")]
2017    #[unstable(feature = "core_float_math", issue = "137578")]
2018    #[must_use = "method returns a new number and does not mutate the original value"]
2019    pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
2020        let r = x % rhs;
2021        if r < 0.0 { r + rhs.abs() } else { r }
2022    }
2023
2024    /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
2025    ///
2026    /// # Examples
2027    ///
2028    /// ```
2029    /// #![feature(core_float_math)]
2030    ///
2031    /// use core::f32;
2032    ///
2033    /// let x = 2.0_f32;
2034    /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
2035    /// assert!(abs_difference <= 1e-5);
2036    ///
2037    /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
2038    /// ```
2039    ///
2040    /// _This standalone function is for testing only.
2041    /// It will be stabilized as an inherent method._
2042    ///
2043    /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
2044    #[inline]
2045    #[must_use = "method returns a new number and does not mutate the original value"]
2046    #[unstable(feature = "core_float_math", issue = "137578")]
2047    pub fn powi(x: f32, n: i32) -> f32 {
2048        intrinsics::powif32(x, n)
2049    }
2050
2051    /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
2052    ///
2053    /// # Examples
2054    ///
2055    /// ```
2056    /// #![feature(core_float_math)]
2057    ///
2058    /// use core::f32;
2059    ///
2060    /// let positive = 4.0_f32;
2061    /// let negative = -4.0_f32;
2062    /// let negative_zero = -0.0_f32;
2063    ///
2064    /// assert_eq!(f32::math::sqrt(positive), 2.0);
2065    /// assert!(f32::math::sqrt(negative).is_nan());
2066    /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
2067    /// ```
2068    ///
2069    /// _This standalone function is for testing only.
2070    /// It will be stabilized as an inherent method._
2071    ///
2072    /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
2073    #[inline]
2074    #[doc(alias = "squareRoot")]
2075    #[unstable(feature = "core_float_math", issue = "137578")]
2076    #[must_use = "method returns a new number and does not mutate the original value"]
2077    pub fn sqrt(x: f32) -> f32 {
2078        intrinsics::sqrtf32(x)
2079    }
2080
2081    /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
2082    ///
2083    /// # Examples
2084    ///
2085    /// ```
2086    /// #![feature(core_float_math)]
2087    ///
2088    /// use core::f32;
2089    ///
2090    /// let x = 3.0f32;
2091    /// let y = -3.0f32;
2092    ///
2093    /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
2094    /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
2095    ///
2096    /// assert!(abs_difference_x <= 1e-6);
2097    /// assert!(abs_difference_y <= 1e-6);
2098    /// ```
2099    ///
2100    /// _This standalone function is for testing only.
2101    /// It will be stabilized as an inherent method._
2102    ///
2103    /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
2104    #[inline]
2105    #[stable(feature = "rust1", since = "1.0.0")]
2106    #[deprecated(
2107        since = "1.10.0",
2108        note = "you probably meant `(self - other).abs()`: \
2109            this operation is `(self - other).max(0.0)` \
2110            except that `abs_sub` also propagates NaNs (also \
2111            known as `fdimf` in C). If you truly need the positive \
2112            difference, consider using that expression or the C function \
2113            `fdimf`, depending on how you wish to handle NaN (please consider \
2114            filing an issue describing your use-case too)."
2115    )]
2116    #[must_use = "method returns a new number and does not mutate the original value"]
2117    pub fn abs_sub(x: f32, other: f32) -> f32 {
2118        libm::fdimf(x, other)
2119    }
2120
2121    /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2122    ///
2123    /// # Unspecified precision
2124    ///
2125    /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2126    /// can even differ within the same execution from one invocation to the next.
2127    /// This function currently corresponds to the `cbrtf` from libc on Unix
2128    /// and Windows. Note that this might change in the future.
2129    ///
2130    /// # Examples
2131    ///
2132    /// ```
2133    /// #![feature(core_float_math)]
2134    ///
2135    /// use core::f32;
2136    ///
2137    /// let x = 8.0f32;
2138    ///
2139    /// // x^(1/3) - 2 == 0
2140    /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2141    ///
2142    /// assert!(abs_difference <= 1e-6);
2143    /// ```
2144    ///
2145    /// _This standalone function is for testing only.
2146    /// It will be stabilized as an inherent method._
2147    ///
2148    /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2149    #[inline]
2150    #[must_use = "method returns a new number and does not mutate the original value"]
2151    #[unstable(feature = "core_float_math", issue = "137578")]
2152    pub fn cbrt(x: f32) -> f32 {
2153        libm::cbrtf(x)
2154    }
2155}