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> 2<sup>[`MANTISSA_DIGITS`] − 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 − [`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 −[`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`] − 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 − 2<sup>−[`MANTISSA_DIGITS`]</sup>) 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 × 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> [`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> [`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 /// Sign bit
576 pub(crate) const SIGN_MASK: u32 = 0x8000_0000;
577
578 /// Exponent mask
579 pub(crate) const EXP_MASK: u32 = 0x7f80_0000;
580
581 /// Mantissa mask
582 pub(crate) const MAN_MASK: u32 = 0x007f_ffff;
583
584 /// Minimum representable positive value (min subnormal)
585 const TINY_BITS: u32 = 0x1;
586
587 /// Minimum representable negative value (min negative subnormal)
588 const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
589
590 /// Returns `true` if this value is NaN.
591 ///
592 /// ```
593 /// let nan = f32::NAN;
594 /// let f = 7.0_f32;
595 ///
596 /// assert!(nan.is_nan());
597 /// assert!(!f.is_nan());
598 /// ```
599 #[must_use]
600 #[stable(feature = "rust1", since = "1.0.0")]
601 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
602 #[inline]
603 #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
604 #[ferrocene::prevalidated]
605 pub const fn is_nan(self) -> bool {
606 self != self
607 }
608
609 /// Returns `true` if this value is positive infinity or negative infinity, and
610 /// `false` otherwise.
611 ///
612 /// ```
613 /// let f = 7.0f32;
614 /// let inf = f32::INFINITY;
615 /// let neg_inf = f32::NEG_INFINITY;
616 /// let nan = f32::NAN;
617 ///
618 /// assert!(!f.is_infinite());
619 /// assert!(!nan.is_infinite());
620 ///
621 /// assert!(inf.is_infinite());
622 /// assert!(neg_inf.is_infinite());
623 /// ```
624 #[must_use]
625 #[stable(feature = "rust1", since = "1.0.0")]
626 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
627 #[inline]
628 #[ferrocene::prevalidated]
629 pub const fn is_infinite(self) -> bool {
630 // Getting clever with transmutation can result in incorrect answers on some FPUs
631 // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
632 // See https://github.com/rust-lang/rust/issues/72327
633 (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
634 }
635
636 /// Returns `true` if this number is neither infinite nor NaN.
637 ///
638 /// ```
639 /// let f = 7.0f32;
640 /// let inf = f32::INFINITY;
641 /// let neg_inf = f32::NEG_INFINITY;
642 /// let nan = f32::NAN;
643 ///
644 /// assert!(f.is_finite());
645 ///
646 /// assert!(!nan.is_finite());
647 /// assert!(!inf.is_finite());
648 /// assert!(!neg_inf.is_finite());
649 /// ```
650 #[must_use]
651 #[stable(feature = "rust1", since = "1.0.0")]
652 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
653 #[inline]
654 pub const fn is_finite(self) -> bool {
655 // There's no need to handle NaN separately: if self is NaN,
656 // the comparison is not true, exactly as desired.
657 self.abs() < Self::INFINITY
658 }
659
660 /// Returns `true` if the number is [subnormal].
661 ///
662 /// ```
663 /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
664 /// let max = f32::MAX;
665 /// let lower_than_min = 1.0e-40_f32;
666 /// let zero = 0.0_f32;
667 ///
668 /// assert!(!min.is_subnormal());
669 /// assert!(!max.is_subnormal());
670 ///
671 /// assert!(!zero.is_subnormal());
672 /// assert!(!f32::NAN.is_subnormal());
673 /// assert!(!f32::INFINITY.is_subnormal());
674 /// // Values between `0` and `min` are Subnormal.
675 /// assert!(lower_than_min.is_subnormal());
676 /// ```
677 /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
678 #[must_use]
679 #[stable(feature = "is_subnormal", since = "1.53.0")]
680 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
681 #[inline]
682 pub const fn is_subnormal(self) -> bool {
683 matches!(self.classify(), FpCategory::Subnormal)
684 }
685
686 /// Returns `true` if the number is neither zero, infinite,
687 /// [subnormal], or NaN.
688 ///
689 /// ```
690 /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
691 /// let max = f32::MAX;
692 /// let lower_than_min = 1.0e-40_f32;
693 /// let zero = 0.0_f32;
694 ///
695 /// assert!(min.is_normal());
696 /// assert!(max.is_normal());
697 ///
698 /// assert!(!zero.is_normal());
699 /// assert!(!f32::NAN.is_normal());
700 /// assert!(!f32::INFINITY.is_normal());
701 /// // Values between `0` and `min` are Subnormal.
702 /// assert!(!lower_than_min.is_normal());
703 /// ```
704 /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
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_normal(self) -> bool {
710 matches!(self.classify(), FpCategory::Normal)
711 }
712
713 /// Returns the floating point category of the number. If only one property
714 /// is going to be tested, it is generally faster to use the specific
715 /// predicate instead.
716 ///
717 /// ```
718 /// use std::num::FpCategory;
719 ///
720 /// let num = 12.4_f32;
721 /// let inf = f32::INFINITY;
722 ///
723 /// assert_eq!(num.classify(), FpCategory::Normal);
724 /// assert_eq!(inf.classify(), FpCategory::Infinite);
725 /// ```
726 #[ferrocene::prevalidated]
727 #[stable(feature = "rust1", since = "1.0.0")]
728 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
729 #[must_use]
730 pub const fn classify(self) -> FpCategory {
731 // We used to have complicated logic here that avoids the simple bit-based tests to work
732 // around buggy codegen for x87 targets (see
733 // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
734 // of our tests is able to find any difference between the complicated and the naive
735 // version, so now we are back to the naive version.
736 let b = self.to_bits();
737 match (b & Self::MAN_MASK, b & Self::EXP_MASK) {
738 (0, Self::EXP_MASK) => FpCategory::Infinite,
739 (_, Self::EXP_MASK) => FpCategory::Nan,
740 (0, 0) => FpCategory::Zero,
741 (_, 0) => FpCategory::Subnormal,
742 _ => FpCategory::Normal,
743 }
744 }
745
746 /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
747 /// positive sign bit and positive infinity.
748 ///
749 /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
750 /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
751 /// conserved over arithmetic operations, the result of `is_sign_positive` on
752 /// a NaN might produce an unexpected or non-portable result. See the [specification
753 /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
754 /// if you need fully portable behavior (will return `false` for all NaNs).
755 ///
756 /// ```
757 /// let f = 7.0_f32;
758 /// let g = -7.0_f32;
759 ///
760 /// assert!(f.is_sign_positive());
761 /// assert!(!g.is_sign_positive());
762 /// ```
763 #[must_use]
764 #[stable(feature = "rust1", since = "1.0.0")]
765 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
766 #[inline]
767 pub const fn is_sign_positive(self) -> bool {
768 !self.is_sign_negative()
769 }
770
771 /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
772 /// negative sign bit and negative infinity.
773 ///
774 /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
775 /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
776 /// conserved over arithmetic operations, the result of `is_sign_negative` on
777 /// a NaN might produce an unexpected or non-portable result. See the [specification
778 /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
779 /// if you need fully portable behavior (will return `false` for all NaNs).
780 ///
781 /// ```
782 /// let f = 7.0f32;
783 /// let g = -7.0f32;
784 ///
785 /// assert!(!f.is_sign_negative());
786 /// assert!(g.is_sign_negative());
787 /// ```
788 #[must_use]
789 #[stable(feature = "rust1", since = "1.0.0")]
790 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
791 #[inline]
792 #[ferrocene::prevalidated]
793 pub const fn is_sign_negative(self) -> bool {
794 // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
795 // applies to zeros and NaNs as well.
796 self.to_bits() & 0x8000_0000 != 0
797 }
798
799 /// Returns the least number greater than `self`.
800 ///
801 /// Let `TINY` be the smallest representable positive `f32`. Then,
802 /// - if `self.is_nan()`, this returns `self`;
803 /// - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
804 /// - if `self` is `-TINY`, this returns -0.0;
805 /// - if `self` is -0.0 or +0.0, this returns `TINY`;
806 /// - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
807 /// - otherwise the unique least value greater than `self` is returned.
808 ///
809 /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
810 /// is finite `x == x.next_up().next_down()` also holds.
811 ///
812 /// ```rust
813 /// // f32::EPSILON is the difference between 1.0 and the next number up.
814 /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
815 /// // But not for most numbers.
816 /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
817 /// assert_eq!(16777216f32.next_up(), 16777218.0);
818 /// ```
819 ///
820 /// This operation corresponds to IEEE-754 `nextUp`.
821 ///
822 /// [`NEG_INFINITY`]: Self::NEG_INFINITY
823 /// [`INFINITY`]: Self::INFINITY
824 /// [`MIN`]: Self::MIN
825 /// [`MAX`]: Self::MAX
826 #[inline]
827 #[doc(alias = "nextUp")]
828 #[stable(feature = "float_next_up_down", since = "1.86.0")]
829 #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
830 #[must_use = "method returns a new number and does not mutate the original value"]
831 pub const fn next_up(self) -> Self {
832 // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
833 // denormals to zero. This is in general unsound and unsupported, but here
834 // we do our best to still produce the correct result on such targets.
835 let bits = self.to_bits();
836 if self.is_nan() || bits == Self::INFINITY.to_bits() {
837 return self;
838 }
839
840 let abs = bits & !Self::SIGN_MASK;
841 let next_bits = if abs == 0 {
842 Self::TINY_BITS
843 } else if bits == abs {
844 bits + 1
845 } else {
846 bits - 1
847 };
848 Self::from_bits(next_bits)
849 }
850
851 /// Returns the greatest number less than `self`.
852 ///
853 /// Let `TINY` be the smallest representable positive `f32`. Then,
854 /// - if `self.is_nan()`, this returns `self`;
855 /// - if `self` is [`INFINITY`], this returns [`MAX`];
856 /// - if `self` is `TINY`, this returns 0.0;
857 /// - if `self` is -0.0 or +0.0, this returns `-TINY`;
858 /// - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
859 /// - otherwise the unique greatest value less than `self` is returned.
860 ///
861 /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
862 /// is finite `x == x.next_down().next_up()` also holds.
863 ///
864 /// ```rust
865 /// let x = 1.0f32;
866 /// // Clamp value into range [0, 1).
867 /// let clamped = x.clamp(0.0, 1.0f32.next_down());
868 /// assert!(clamped < 1.0);
869 /// assert_eq!(clamped.next_up(), 1.0);
870 /// ```
871 ///
872 /// This operation corresponds to IEEE-754 `nextDown`.
873 ///
874 /// [`NEG_INFINITY`]: Self::NEG_INFINITY
875 /// [`INFINITY`]: Self::INFINITY
876 /// [`MIN`]: Self::MIN
877 /// [`MAX`]: Self::MAX
878 #[inline]
879 #[doc(alias = "nextDown")]
880 #[stable(feature = "float_next_up_down", since = "1.86.0")]
881 #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
882 #[must_use = "method returns a new number and does not mutate the original value"]
883 pub const fn next_down(self) -> Self {
884 // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
885 // denormals to zero. This is in general unsound and unsupported, but here
886 // we do our best to still produce the correct result on such targets.
887 let bits = self.to_bits();
888 if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
889 return self;
890 }
891
892 let abs = bits & !Self::SIGN_MASK;
893 let next_bits = if abs == 0 {
894 Self::NEG_TINY_BITS
895 } else if bits == abs {
896 bits - 1
897 } else {
898 bits + 1
899 };
900 Self::from_bits(next_bits)
901 }
902
903 /// Takes the reciprocal (inverse) of a number, `1/x`.
904 ///
905 /// ```
906 /// let x = 2.0_f32;
907 /// let abs_difference = (x.recip() - (1.0 / x)).abs();
908 ///
909 /// assert!(abs_difference <= f32::EPSILON);
910 /// ```
911 #[must_use = "this returns the result of the operation, without modifying the original"]
912 #[stable(feature = "rust1", since = "1.0.0")]
913 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
914 #[inline]
915 pub const fn recip(self) -> f32 {
916 1.0 / self
917 }
918
919 /// Converts radians to degrees.
920 ///
921 /// # Unspecified precision
922 ///
923 /// The precision of this function is non-deterministic. This means it varies by platform,
924 /// Rust version, and can even differ within the same execution from one invocation to the next.
925 ///
926 /// # Examples
927 ///
928 /// ```
929 /// let angle = std::f32::consts::PI;
930 ///
931 /// let abs_difference = (angle.to_degrees() - 180.0).abs();
932 /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
933 /// assert!(abs_difference <= f32::EPSILON);
934 /// ```
935 #[must_use = "this returns the result of the operation, \
936 without modifying the original"]
937 #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
938 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
939 #[inline]
940 pub const fn to_degrees(self) -> f32 {
941 // Use a literal to avoid double rounding, consts::PI is already rounded,
942 // and dividing would round again.
943 const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
944 self * PIS_IN_180
945 }
946
947 /// Converts degrees to radians.
948 ///
949 /// # Unspecified precision
950 ///
951 /// The precision of this function is non-deterministic. This means it varies by platform,
952 /// Rust version, and can even differ within the same execution from one invocation to the next.
953 ///
954 /// # Examples
955 ///
956 /// ```
957 /// let angle = 180.0f32;
958 ///
959 /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
960 ///
961 /// assert!(abs_difference <= f32::EPSILON);
962 /// ```
963 #[must_use = "this returns the result of the operation, \
964 without modifying the original"]
965 #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
966 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
967 #[inline]
968 pub const fn to_radians(self) -> f32 {
969 // The division here is correctly rounded with respect to the true value of π/180.
970 // Although π is irrational and already rounded, the double rounding happens
971 // to produce correct result for f32.
972 const RADS_PER_DEG: f32 = consts::PI / 180.0;
973 self * RADS_PER_DEG
974 }
975
976 /// Returns the maximum of the two numbers, ignoring NaN.
977 ///
978 /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
979 /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
980 /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
981 /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
982 /// non-deterministically.
983 ///
984 /// The handling of NaNs follows the IEEE 754-2019 semantics for `maximumNumber`, treating all
985 /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
986 /// follows the IEEE 754-2008 semantics for `maxNum`.
987 ///
988 /// ```
989 /// let x = 1.0f32;
990 /// let y = 2.0f32;
991 ///
992 /// assert_eq!(x.max(y), y);
993 /// assert_eq!(x.max(f32::NAN), x);
994 /// ```
995 #[must_use = "this returns the result of the comparison, without modifying either input"]
996 #[stable(feature = "rust1", since = "1.0.0")]
997 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
998 #[inline]
999 #[ferrocene::prevalidated]
1000 pub const fn max(self, other: f32) -> f32 {
1001 intrinsics::maximum_number_nsz_f32(self, other)
1002 }
1003
1004 /// Returns the minimum of the two numbers, ignoring NaN.
1005 ///
1006 /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
1007 /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1008 /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1009 /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1010 /// non-deterministically.
1011 ///
1012 /// The handling of NaNs follows the IEEE 754-2019 semantics for `minimumNumber`, treating all
1013 /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1014 /// follows the IEEE 754-2008 semantics for `minNum`.
1015 ///
1016 /// ```
1017 /// let x = 1.0f32;
1018 /// let y = 2.0f32;
1019 ///
1020 /// assert_eq!(x.min(y), x);
1021 /// assert_eq!(x.min(f32::NAN), x);
1022 /// ```
1023 #[must_use = "this returns the result of the comparison, without modifying either input"]
1024 #[stable(feature = "rust1", since = "1.0.0")]
1025 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1026 #[inline]
1027 #[ferrocene::prevalidated]
1028 pub const fn min(self, other: f32) -> f32 {
1029 intrinsics::minimum_number_nsz_f32(self, other)
1030 }
1031
1032 /// Returns the maximum of the two numbers, propagating NaN.
1033 ///
1034 /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1035 /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1036 /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1037 /// non-NaN inputs.
1038 ///
1039 /// This is in contrast to [`f32::max`] which only returns NaN when *both* arguments are NaN,
1040 /// and which does not reliably order `-0.0` and `+0.0`.
1041 ///
1042 /// This follows the IEEE 754-2019 semantics for `maximum`.
1043 ///
1044 /// ```
1045 /// #![feature(float_minimum_maximum)]
1046 /// let x = 1.0f32;
1047 /// let y = 2.0f32;
1048 ///
1049 /// assert_eq!(x.maximum(y), y);
1050 /// assert!(x.maximum(f32::NAN).is_nan());
1051 /// ```
1052 #[must_use = "this returns the result of the comparison, without modifying either input"]
1053 #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1054 #[inline]
1055 pub const fn maximum(self, other: f32) -> f32 {
1056 intrinsics::maximumf32(self, other)
1057 }
1058
1059 /// Returns the minimum of the two numbers, propagating NaN.
1060 ///
1061 /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1062 /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1063 /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1064 /// non-NaN inputs.
1065 ///
1066 /// This is in contrast to [`f32::min`] which only returns NaN when *both* arguments are NaN,
1067 /// and which does not reliably order `-0.0` and `+0.0`.
1068 ///
1069 /// This follows the IEEE 754-2019 semantics for `minimum`.
1070 ///
1071 /// ```
1072 /// #![feature(float_minimum_maximum)]
1073 /// let x = 1.0f32;
1074 /// let y = 2.0f32;
1075 ///
1076 /// assert_eq!(x.minimum(y), x);
1077 /// assert!(x.minimum(f32::NAN).is_nan());
1078 /// ```
1079 #[must_use = "this returns the result of the comparison, without modifying either input"]
1080 #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1081 #[inline]
1082 pub const fn minimum(self, other: f32) -> f32 {
1083 intrinsics::minimumf32(self, other)
1084 }
1085
1086 /// Calculates the midpoint (average) between `self` and `rhs`.
1087 ///
1088 /// This returns NaN when *either* argument is NaN or if a combination of
1089 /// +inf and -inf is provided as arguments.
1090 ///
1091 /// # Examples
1092 ///
1093 /// ```
1094 /// assert_eq!(1f32.midpoint(4.0), 2.5);
1095 /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1096 /// ```
1097 #[inline]
1098 #[doc(alias = "average")]
1099 #[stable(feature = "num_midpoint", since = "1.85.0")]
1100 #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1101 #[must_use = "this returns the result of the operation, \
1102 without modifying the original"]
1103 pub const fn midpoint(self, other: f32) -> f32 {
1104 cfg_select! {
1105 // Allow faster implementation that have known good 64-bit float
1106 // implementations. Falling back to the branchy code on targets that don't
1107 // have 64-bit hardware floats or buggy implementations.
1108 // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1109 any(
1110 target_arch = "x86_64",
1111 target_arch = "aarch64",
1112 all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1113 all(target_arch = "loongarch64", target_feature = "d"),
1114 all(target_arch = "arm", target_feature = "vfp2"),
1115 target_arch = "wasm32",
1116 target_arch = "wasm64",
1117 ) => {
1118 ((self as f64 + other as f64) / 2.0) as f32
1119 }
1120 _ => {
1121 const HI: f32 = f32::MAX / 2.;
1122
1123 let (a, b) = (self, other);
1124 let abs_a = a.abs();
1125 let abs_b = b.abs();
1126
1127 if abs_a <= HI && abs_b <= HI {
1128 // Overflow is impossible
1129 (a + b) / 2.
1130 } else {
1131 (a / 2.) + (b / 2.)
1132 }
1133 }
1134 }
1135 }
1136
1137 /// Rounds toward zero and converts to any primitive integer type,
1138 /// assuming that the value is finite and fits in that type.
1139 ///
1140 /// ```
1141 /// let value = 4.6_f32;
1142 /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1143 /// assert_eq!(rounded, 4);
1144 ///
1145 /// let value = -128.9_f32;
1146 /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1147 /// assert_eq!(rounded, i8::MIN);
1148 /// ```
1149 ///
1150 /// # Safety
1151 ///
1152 /// The value must:
1153 ///
1154 /// * Not be `NaN`
1155 /// * Not be infinite
1156 /// * Be representable in the return type `Int`, after truncating off its fractional part
1157 #[must_use = "this returns the result of the operation, \
1158 without modifying the original"]
1159 #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1160 #[inline]
1161 pub unsafe fn to_int_unchecked<Int>(self) -> Int
1162 where
1163 Self: FloatToInt<Int>,
1164 {
1165 // SAFETY: the caller must uphold the safety contract for
1166 // `FloatToInt::to_int_unchecked`.
1167 unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1168 }
1169
1170 /// Raw transmutation to `u32`.
1171 ///
1172 /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1173 ///
1174 /// See [`from_bits`](Self::from_bits) for some discussion of the
1175 /// portability of this operation (there are almost no issues).
1176 ///
1177 /// Note that this function is distinct from `as` casting, which attempts to
1178 /// preserve the *numeric* value, and not the bitwise value.
1179 ///
1180 /// # Examples
1181 ///
1182 /// ```
1183 /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1184 /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1185 ///
1186 /// ```
1187 #[must_use = "this returns the result of the operation, \
1188 without modifying the original"]
1189 #[stable(feature = "float_bits_conv", since = "1.20.0")]
1190 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1191 #[inline]
1192 #[allow(unnecessary_transmutes)]
1193 #[ferrocene::prevalidated]
1194 pub const fn to_bits(self) -> u32 {
1195 // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1196 unsafe { mem::transmute(self) }
1197 }
1198
1199 /// Raw transmutation from `u32`.
1200 ///
1201 /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1202 /// It turns out this is incredibly portable, for two reasons:
1203 ///
1204 /// * Floats and Ints have the same endianness on all supported platforms.
1205 /// * IEEE 754 very precisely specifies the bit layout of floats.
1206 ///
1207 /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1208 /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1209 /// (notably x86 and ARM) picked the interpretation that was ultimately
1210 /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1211 /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1212 ///
1213 /// Rather than trying to preserve signaling-ness cross-platform, this
1214 /// implementation favors preserving the exact bits. This means that
1215 /// any payloads encoded in NaNs will be preserved even if the result of
1216 /// this method is sent over the network from an x86 machine to a MIPS one.
1217 ///
1218 /// If the results of this method are only manipulated by the same
1219 /// architecture that produced them, then there is no portability concern.
1220 ///
1221 /// If the input isn't NaN, then there is no portability concern.
1222 ///
1223 /// If you don't care about signalingness (very likely), then there is no
1224 /// portability concern.
1225 ///
1226 /// Note that this function is distinct from `as` casting, which attempts to
1227 /// preserve the *numeric* value, and not the bitwise value.
1228 ///
1229 /// # Examples
1230 ///
1231 /// ```
1232 /// let v = f32::from_bits(0x41480000);
1233 /// assert_eq!(v, 12.5);
1234 /// ```
1235 #[stable(feature = "float_bits_conv", since = "1.20.0")]
1236 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1237 #[must_use]
1238 #[inline]
1239 #[allow(unnecessary_transmutes)]
1240 #[ferrocene::prevalidated]
1241 pub const fn from_bits(v: u32) -> Self {
1242 // It turns out the safety issues with sNaN were overblown! Hooray!
1243 // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1244 unsafe { mem::transmute(v) }
1245 }
1246
1247 /// Returns the memory representation of this floating point number as a byte array in
1248 /// big-endian (network) byte order.
1249 ///
1250 /// See [`from_bits`](Self::from_bits) for some discussion of the
1251 /// portability of this operation (there are almost no issues).
1252 ///
1253 /// # Examples
1254 ///
1255 /// ```
1256 /// let bytes = 12.5f32.to_be_bytes();
1257 /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1258 /// ```
1259 #[must_use = "this returns the result of the operation, \
1260 without modifying the original"]
1261 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1262 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1263 #[inline]
1264 pub const fn to_be_bytes(self) -> [u8; 4] {
1265 self.to_bits().to_be_bytes()
1266 }
1267
1268 /// Returns the memory representation of this floating point number as a byte array in
1269 /// little-endian byte order.
1270 ///
1271 /// See [`from_bits`](Self::from_bits) for some discussion of the
1272 /// portability of this operation (there are almost no issues).
1273 ///
1274 /// # Examples
1275 ///
1276 /// ```
1277 /// let bytes = 12.5f32.to_le_bytes();
1278 /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1279 /// ```
1280 #[must_use = "this returns the result of the operation, \
1281 without modifying the original"]
1282 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1283 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1284 #[inline]
1285 #[ferrocene::prevalidated]
1286 pub const fn to_le_bytes(self) -> [u8; 4] {
1287 self.to_bits().to_le_bytes()
1288 }
1289
1290 /// Returns the memory representation of this floating point number as a byte array in
1291 /// native byte order.
1292 ///
1293 /// As the target platform's native endianness is used, portable code
1294 /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1295 ///
1296 /// [`to_be_bytes`]: f32::to_be_bytes
1297 /// [`to_le_bytes`]: f32::to_le_bytes
1298 ///
1299 /// See [`from_bits`](Self::from_bits) for some discussion of the
1300 /// portability of this operation (there are almost no issues).
1301 ///
1302 /// # Examples
1303 ///
1304 /// ```
1305 /// let bytes = 12.5f32.to_ne_bytes();
1306 /// assert_eq!(
1307 /// bytes,
1308 /// if cfg!(target_endian = "big") {
1309 /// [0x41, 0x48, 0x00, 0x00]
1310 /// } else {
1311 /// [0x00, 0x00, 0x48, 0x41]
1312 /// }
1313 /// );
1314 /// ```
1315 #[must_use = "this returns the result of the operation, \
1316 without modifying the original"]
1317 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1318 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1319 #[inline]
1320 pub const fn to_ne_bytes(self) -> [u8; 4] {
1321 self.to_bits().to_ne_bytes()
1322 }
1323
1324 /// Creates a floating point value from its representation as a byte array in big endian.
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 value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1333 /// assert_eq!(value, 12.5);
1334 /// ```
1335 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1336 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1337 #[must_use]
1338 #[inline]
1339 pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1340 Self::from_bits(u32::from_be_bytes(bytes))
1341 }
1342
1343 /// Creates a floating point value from its representation as a byte array in little endian.
1344 ///
1345 /// See [`from_bits`](Self::from_bits) for some discussion of the
1346 /// portability of this operation (there are almost no issues).
1347 ///
1348 /// # Examples
1349 ///
1350 /// ```
1351 /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1352 /// assert_eq!(value, 12.5);
1353 /// ```
1354 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1355 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1356 #[must_use]
1357 #[inline]
1358 #[ferrocene::prevalidated]
1359 pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1360 Self::from_bits(u32::from_le_bytes(bytes))
1361 }
1362
1363 /// Creates a floating point value from its representation as a byte array in native endian.
1364 ///
1365 /// As the target platform's native endianness is used, portable code
1366 /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1367 /// appropriate instead.
1368 ///
1369 /// [`from_be_bytes`]: f32::from_be_bytes
1370 /// [`from_le_bytes`]: f32::from_le_bytes
1371 ///
1372 /// See [`from_bits`](Self::from_bits) for some discussion of the
1373 /// portability of this operation (there are almost no issues).
1374 ///
1375 /// # Examples
1376 ///
1377 /// ```
1378 /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1379 /// [0x41, 0x48, 0x00, 0x00]
1380 /// } else {
1381 /// [0x00, 0x00, 0x48, 0x41]
1382 /// });
1383 /// assert_eq!(value, 12.5);
1384 /// ```
1385 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1386 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1387 #[must_use]
1388 #[inline]
1389 pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1390 Self::from_bits(u32::from_ne_bytes(bytes))
1391 }
1392
1393 /// Returns the ordering between `self` and `other`.
1394 ///
1395 /// Unlike the standard partial comparison between floating point numbers,
1396 /// this comparison always produces an ordering in accordance to
1397 /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1398 /// floating point standard. The values are ordered in the following sequence:
1399 ///
1400 /// - negative quiet NaN
1401 /// - negative signaling NaN
1402 /// - negative infinity
1403 /// - negative numbers
1404 /// - negative subnormal numbers
1405 /// - negative zero
1406 /// - positive zero
1407 /// - positive subnormal numbers
1408 /// - positive numbers
1409 /// - positive infinity
1410 /// - positive signaling NaN
1411 /// - positive quiet NaN.
1412 ///
1413 /// The ordering established by this function does not always agree with the
1414 /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1415 /// they consider negative and positive zero equal, while `total_cmp`
1416 /// doesn't.
1417 ///
1418 /// The interpretation of the signaling NaN bit follows the definition in
1419 /// the IEEE 754 standard, which may not match the interpretation by some of
1420 /// the older, non-conformant (e.g. MIPS) hardware implementations.
1421 ///
1422 /// # Example
1423 ///
1424 /// ```
1425 /// struct GoodBoy {
1426 /// name: String,
1427 /// weight: f32,
1428 /// }
1429 ///
1430 /// let mut bois = vec![
1431 /// GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1432 /// GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1433 /// GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1434 /// GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1435 /// GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1436 /// GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1437 /// ];
1438 ///
1439 /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1440 ///
1441 /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1442 /// if f32::NAN.is_sign_negative() {
1443 /// assert!(bois.into_iter().map(|b| b.weight)
1444 /// .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1445 /// .all(|(a, b)| a.to_bits() == b.to_bits()))
1446 /// } else {
1447 /// assert!(bois.into_iter().map(|b| b.weight)
1448 /// .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1449 /// .all(|(a, b)| a.to_bits() == b.to_bits()))
1450 /// }
1451 /// ```
1452 #[stable(feature = "total_cmp", since = "1.62.0")]
1453 #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1454 #[must_use]
1455 #[inline]
1456 pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1457 let mut left = self.to_bits() as i32;
1458 let mut right = other.to_bits() as i32;
1459
1460 // In case of negatives, flip all the bits except the sign
1461 // to achieve a similar layout as two's complement integers
1462 //
1463 // Why does this work? IEEE 754 floats consist of three fields:
1464 // Sign bit, exponent and mantissa. The set of exponent and mantissa
1465 // fields as a whole have the property that their bitwise order is
1466 // equal to the numeric magnitude where the magnitude is defined.
1467 // The magnitude is not normally defined on NaN values, but
1468 // IEEE 754 totalOrder defines the NaN values also to follow the
1469 // bitwise order. This leads to order explained in the doc comment.
1470 // However, the representation of magnitude is the same for negative
1471 // and positive numbers – only the sign bit is different.
1472 // To easily compare the floats as signed integers, we need to
1473 // flip the exponent and mantissa bits in case of negative numbers.
1474 // We effectively convert the numbers to "two's complement" form.
1475 //
1476 // To do the flipping, we construct a mask and XOR against it.
1477 // We branchlessly calculate an "all-ones except for the sign bit"
1478 // mask from negative-signed values: right shifting sign-extends
1479 // the integer, so we "fill" the mask with sign bits, and then
1480 // convert to unsigned to push one more zero bit.
1481 // On positive values, the mask is all zeros, so it's a no-op.
1482 left ^= (((left >> 31) as u32) >> 1) as i32;
1483 right ^= (((right >> 31) as u32) >> 1) as i32;
1484
1485 left.cmp(&right)
1486 }
1487
1488 /// Restrict a value to a certain interval unless it is NaN.
1489 ///
1490 /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1491 /// less than `min`. Otherwise this returns `self`.
1492 ///
1493 /// Note that this function returns NaN if the initial value was NaN as
1494 /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1495 /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1496 ///
1497 /// # Panics
1498 ///
1499 /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1500 ///
1501 /// # Examples
1502 ///
1503 /// ```
1504 /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1505 /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1506 /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1507 /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1508 ///
1509 /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1510 /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1511 /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1512 /// // This is definitely a negative zero.
1513 /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1514 /// ```
1515 #[must_use = "method returns a new number and does not mutate the original value"]
1516 #[stable(feature = "clamp", since = "1.50.0")]
1517 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1518 #[inline]
1519 pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1520 const_assert!(
1521 min <= max,
1522 "min > max, or either was NaN",
1523 "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1524 min: f32,
1525 max: f32,
1526 );
1527
1528 if self < min {
1529 self = min;
1530 }
1531 if self > max {
1532 self = max;
1533 }
1534 self
1535 }
1536
1537 /// Clamps this number to a symmetric range centered around zero.
1538 ///
1539 /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1540 ///
1541 /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1542 /// explicit about the intent.
1543 ///
1544 /// # Panics
1545 ///
1546 /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1547 ///
1548 /// # Examples
1549 ///
1550 /// ```
1551 /// #![feature(clamp_magnitude)]
1552 /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1553 /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1554 /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1555 /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1556 /// ```
1557 #[must_use = "this returns the clamped value and does not modify the original"]
1558 #[unstable(feature = "clamp_magnitude", issue = "148519")]
1559 #[inline]
1560 pub fn clamp_magnitude(self, limit: f32) -> f32 {
1561 assert!(limit >= 0.0, "limit must be non-negative");
1562 let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1563 self.clamp(-limit, limit)
1564 }
1565
1566 /// Computes the absolute value of `self`.
1567 ///
1568 /// This function always returns the precise result.
1569 ///
1570 /// # Examples
1571 ///
1572 /// ```
1573 /// let x = 3.5_f32;
1574 /// let y = -3.5_f32;
1575 ///
1576 /// assert_eq!(x.abs(), x);
1577 /// assert_eq!(y.abs(), -y);
1578 ///
1579 /// assert!(f32::NAN.abs().is_nan());
1580 /// ```
1581 #[must_use = "method returns a new number and does not mutate the original value"]
1582 #[stable(feature = "rust1", since = "1.0.0")]
1583 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1584 #[inline]
1585 #[ferrocene::prevalidated]
1586 pub const fn abs(self) -> f32 {
1587 intrinsics::fabs(self)
1588 }
1589
1590 /// Returns a number that represents the sign of `self`.
1591 ///
1592 /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1593 /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1594 /// - NaN if the number is NaN
1595 ///
1596 /// # Examples
1597 ///
1598 /// ```
1599 /// let f = 3.5_f32;
1600 ///
1601 /// assert_eq!(f.signum(), 1.0);
1602 /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1603 ///
1604 /// assert!(f32::NAN.signum().is_nan());
1605 /// ```
1606 #[must_use = "method returns a new number and does not mutate the original value"]
1607 #[stable(feature = "rust1", since = "1.0.0")]
1608 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1609 #[inline]
1610 #[ferrocene::prevalidated]
1611 pub const fn signum(self) -> f32 {
1612 if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1613 }
1614
1615 /// Returns a number composed of the magnitude of `self` and the sign of
1616 /// `sign`.
1617 ///
1618 /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1619 /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1620 /// returned.
1621 ///
1622 /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1623 /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1624 /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1625 /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1626 /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1627 /// info.
1628 ///
1629 /// # Examples
1630 ///
1631 /// ```
1632 /// let f = 3.5_f32;
1633 ///
1634 /// assert_eq!(f.copysign(0.42), 3.5_f32);
1635 /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1636 /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1637 /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1638 ///
1639 /// assert!(f32::NAN.copysign(1.0).is_nan());
1640 /// ```
1641 #[must_use = "method returns a new number and does not mutate the original value"]
1642 #[inline]
1643 #[stable(feature = "copysign", since = "1.35.0")]
1644 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1645 #[ferrocene::prevalidated]
1646 pub const fn copysign(self, sign: f32) -> f32 {
1647 intrinsics::copysignf32(self, sign)
1648 }
1649
1650 /// Float addition that allows optimizations based on algebraic rules.
1651 ///
1652 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1653 #[must_use = "method returns a new number and does not mutate the original value"]
1654 #[unstable(feature = "float_algebraic", issue = "136469")]
1655 #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1656 #[inline]
1657 pub const fn algebraic_add(self, rhs: f32) -> f32 {
1658 intrinsics::fadd_algebraic(self, rhs)
1659 }
1660
1661 /// Float subtraction that allows optimizations based on algebraic rules.
1662 ///
1663 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1664 #[must_use = "method returns a new number and does not mutate the original value"]
1665 #[unstable(feature = "float_algebraic", issue = "136469")]
1666 #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1667 #[inline]
1668 pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1669 intrinsics::fsub_algebraic(self, rhs)
1670 }
1671
1672 /// Float multiplication that allows optimizations based on algebraic rules.
1673 ///
1674 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1675 #[must_use = "method returns a new number and does not mutate the original value"]
1676 #[unstable(feature = "float_algebraic", issue = "136469")]
1677 #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1678 #[inline]
1679 pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1680 intrinsics::fmul_algebraic(self, rhs)
1681 }
1682
1683 /// Float division that allows optimizations based on algebraic rules.
1684 ///
1685 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1686 #[must_use = "method returns a new number and does not mutate the original value"]
1687 #[unstable(feature = "float_algebraic", issue = "136469")]
1688 #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1689 #[inline]
1690 pub const fn algebraic_div(self, rhs: f32) -> f32 {
1691 intrinsics::fdiv_algebraic(self, rhs)
1692 }
1693
1694 /// Float remainder that allows optimizations based on algebraic rules.
1695 ///
1696 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1697 #[must_use = "method returns a new number and does not mutate the original value"]
1698 #[unstable(feature = "float_algebraic", issue = "136469")]
1699 #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1700 #[inline]
1701 pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1702 intrinsics::frem_algebraic(self, rhs)
1703 }
1704}
1705
1706/// Experimental implementations of floating point functions in `core`.
1707///
1708/// _The standalone functions in this module are for testing only.
1709/// They will be stabilized as inherent methods._
1710#[unstable(feature = "core_float_math", issue = "137578")]
1711pub mod math {
1712 use crate::intrinsics;
1713 use crate::num::imp::libm;
1714
1715 /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1716 ///
1717 /// # Examples
1718 ///
1719 /// ```
1720 /// #![feature(core_float_math)]
1721 ///
1722 /// use core::f32;
1723 ///
1724 /// let f = 3.7_f32;
1725 /// let g = 3.0_f32;
1726 /// let h = -3.7_f32;
1727 ///
1728 /// assert_eq!(f32::math::floor(f), 3.0);
1729 /// assert_eq!(f32::math::floor(g), 3.0);
1730 /// assert_eq!(f32::math::floor(h), -4.0);
1731 /// ```
1732 ///
1733 /// _This standalone function is for testing only.
1734 /// It will be stabilized as an inherent method._
1735 ///
1736 /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1737 #[inline]
1738 #[unstable(feature = "core_float_math", issue = "137578")]
1739 #[must_use = "method returns a new number and does not mutate the original value"]
1740 pub const fn floor(x: f32) -> f32 {
1741 intrinsics::floorf32(x)
1742 }
1743
1744 /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1745 ///
1746 /// # Examples
1747 ///
1748 /// ```
1749 /// #![feature(core_float_math)]
1750 ///
1751 /// use core::f32;
1752 ///
1753 /// let f = 3.01_f32;
1754 /// let g = 4.0_f32;
1755 ///
1756 /// assert_eq!(f32::math::ceil(f), 4.0);
1757 /// assert_eq!(f32::math::ceil(g), 4.0);
1758 /// ```
1759 ///
1760 /// _This standalone function is for testing only.
1761 /// It will be stabilized as an inherent method._
1762 ///
1763 /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1764 #[inline]
1765 #[doc(alias = "ceiling")]
1766 #[must_use = "method returns a new number and does not mutate the original value"]
1767 #[unstable(feature = "core_float_math", issue = "137578")]
1768 pub const fn ceil(x: f32) -> f32 {
1769 intrinsics::ceilf32(x)
1770 }
1771
1772 /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1773 ///
1774 /// # Examples
1775 ///
1776 /// ```
1777 /// #![feature(core_float_math)]
1778 ///
1779 /// use core::f32;
1780 ///
1781 /// let f = 3.3_f32;
1782 /// let g = -3.3_f32;
1783 /// let h = -3.7_f32;
1784 /// let i = 3.5_f32;
1785 /// let j = 4.5_f32;
1786 ///
1787 /// assert_eq!(f32::math::round(f), 3.0);
1788 /// assert_eq!(f32::math::round(g), -3.0);
1789 /// assert_eq!(f32::math::round(h), -4.0);
1790 /// assert_eq!(f32::math::round(i), 4.0);
1791 /// assert_eq!(f32::math::round(j), 5.0);
1792 /// ```
1793 ///
1794 /// _This standalone function is for testing only.
1795 /// It will be stabilized as an inherent method._
1796 ///
1797 /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
1798 #[inline]
1799 #[unstable(feature = "core_float_math", issue = "137578")]
1800 #[must_use = "method returns a new number and does not mutate the original value"]
1801 pub const fn round(x: f32) -> f32 {
1802 intrinsics::roundf32(x)
1803 }
1804
1805 /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
1806 /// details.
1807 ///
1808 /// # Examples
1809 ///
1810 /// ```
1811 /// #![feature(core_float_math)]
1812 ///
1813 /// use core::f32;
1814 ///
1815 /// let f = 3.3_f32;
1816 /// let g = -3.3_f32;
1817 /// let h = 3.5_f32;
1818 /// let i = 4.5_f32;
1819 ///
1820 /// assert_eq!(f32::math::round_ties_even(f), 3.0);
1821 /// assert_eq!(f32::math::round_ties_even(g), -3.0);
1822 /// assert_eq!(f32::math::round_ties_even(h), 4.0);
1823 /// assert_eq!(f32::math::round_ties_even(i), 4.0);
1824 /// ```
1825 ///
1826 /// _This standalone function is for testing only.
1827 /// It will be stabilized as an inherent method._
1828 ///
1829 /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
1830 #[inline]
1831 #[unstable(feature = "core_float_math", issue = "137578")]
1832 #[must_use = "method returns a new number and does not mutate the original value"]
1833 pub const fn round_ties_even(x: f32) -> f32 {
1834 intrinsics::round_ties_even_f32(x)
1835 }
1836
1837 /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
1838 ///
1839 /// # Examples
1840 ///
1841 /// ```
1842 /// #![feature(core_float_math)]
1843 ///
1844 /// use core::f32;
1845 ///
1846 /// let f = 3.7_f32;
1847 /// let g = 3.0_f32;
1848 /// let h = -3.7_f32;
1849 ///
1850 /// assert_eq!(f32::math::trunc(f), 3.0);
1851 /// assert_eq!(f32::math::trunc(g), 3.0);
1852 /// assert_eq!(f32::math::trunc(h), -3.0);
1853 /// ```
1854 ///
1855 /// _This standalone function is for testing only.
1856 /// It will be stabilized as an inherent method._
1857 ///
1858 /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
1859 #[inline]
1860 #[doc(alias = "truncate")]
1861 #[must_use = "method returns a new number and does not mutate the original value"]
1862 #[unstable(feature = "core_float_math", issue = "137578")]
1863 pub const fn trunc(x: f32) -> f32 {
1864 intrinsics::truncf32(x)
1865 }
1866
1867 /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
1868 ///
1869 /// # Examples
1870 ///
1871 /// ```
1872 /// #![feature(core_float_math)]
1873 ///
1874 /// use core::f32;
1875 ///
1876 /// let x = 3.6_f32;
1877 /// let y = -3.6_f32;
1878 /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
1879 /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
1880 ///
1881 /// assert!(abs_difference_x <= f32::EPSILON);
1882 /// assert!(abs_difference_y <= f32::EPSILON);
1883 /// ```
1884 ///
1885 /// _This standalone function is for testing only.
1886 /// It will be stabilized as an inherent method._
1887 ///
1888 /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
1889 #[inline]
1890 #[unstable(feature = "core_float_math", issue = "137578")]
1891 #[must_use = "method returns a new number and does not mutate the original value"]
1892 pub const fn fract(x: f32) -> f32 {
1893 x - trunc(x)
1894 }
1895
1896 /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
1897 ///
1898 /// # Examples
1899 ///
1900 /// ```
1901 /// # #![allow(unused_features)]
1902 /// #![feature(core_float_math)]
1903 ///
1904 /// # // FIXME(#140515): mingw has an incorrect fma
1905 /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
1906 /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
1907 /// use core::f32;
1908 ///
1909 /// let m = 10.0_f32;
1910 /// let x = 4.0_f32;
1911 /// let b = 60.0_f32;
1912 ///
1913 /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
1914 /// assert_eq!(m * x + b, 100.0);
1915 ///
1916 /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
1917 /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
1918 /// let minus_one = -1.0_f32;
1919 ///
1920 /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
1921 /// assert_eq!(
1922 /// f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
1923 /// -f32::EPSILON * f32::EPSILON
1924 /// );
1925 /// // Different rounding with the non-fused multiply and add.
1926 /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
1927 /// # }
1928 /// ```
1929 ///
1930 /// _This standalone function is for testing only.
1931 /// It will be stabilized as an inherent method._
1932 ///
1933 /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
1934 #[inline]
1935 #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
1936 #[must_use = "method returns a new number and does not mutate the original value"]
1937 #[unstable(feature = "core_float_math", issue = "137578")]
1938 pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
1939 intrinsics::fmaf32(x, y, z)
1940 }
1941
1942 /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
1943 ///
1944 /// # Examples
1945 ///
1946 /// ```
1947 /// #![feature(core_float_math)]
1948 ///
1949 /// use core::f32;
1950 ///
1951 /// let a: f32 = 7.0;
1952 /// let b = 4.0;
1953 /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
1954 /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
1955 /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
1956 /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
1957 /// ```
1958 ///
1959 /// _This standalone function is for testing only.
1960 /// It will be stabilized as an inherent method._
1961 ///
1962 /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
1963 #[inline]
1964 #[unstable(feature = "core_float_math", issue = "137578")]
1965 #[must_use = "method returns a new number and does not mutate the original value"]
1966 pub fn div_euclid(x: f32, rhs: f32) -> f32 {
1967 let q = trunc(x / rhs);
1968 if x % rhs < 0.0 {
1969 return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
1970 }
1971 q
1972 }
1973
1974 /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
1975 ///
1976 /// # Examples
1977 ///
1978 /// ```
1979 /// #![feature(core_float_math)]
1980 ///
1981 /// use core::f32;
1982 ///
1983 /// let a: f32 = 7.0;
1984 /// let b = 4.0;
1985 /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
1986 /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
1987 /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
1988 /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
1989 /// // limitation due to round-off error
1990 /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
1991 /// ```
1992 ///
1993 /// _This standalone function is for testing only.
1994 /// It will be stabilized as an inherent method._
1995 ///
1996 /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
1997 #[inline]
1998 #[doc(alias = "modulo", alias = "mod")]
1999 #[unstable(feature = "core_float_math", issue = "137578")]
2000 #[must_use = "method returns a new number and does not mutate the original value"]
2001 pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
2002 let r = x % rhs;
2003 if r < 0.0 { r + rhs.abs() } else { r }
2004 }
2005
2006 /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
2007 ///
2008 /// # Examples
2009 ///
2010 /// ```
2011 /// #![feature(core_float_math)]
2012 ///
2013 /// use core::f32;
2014 ///
2015 /// let x = 2.0_f32;
2016 /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
2017 /// assert!(abs_difference <= 1e-5);
2018 ///
2019 /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
2020 /// ```
2021 ///
2022 /// _This standalone function is for testing only.
2023 /// It will be stabilized as an inherent method._
2024 ///
2025 /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
2026 #[inline]
2027 #[must_use = "method returns a new number and does not mutate the original value"]
2028 #[unstable(feature = "core_float_math", issue = "137578")]
2029 pub fn powi(x: f32, n: i32) -> f32 {
2030 intrinsics::powif32(x, n)
2031 }
2032
2033 /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
2034 ///
2035 /// # Examples
2036 ///
2037 /// ```
2038 /// #![feature(core_float_math)]
2039 ///
2040 /// use core::f32;
2041 ///
2042 /// let positive = 4.0_f32;
2043 /// let negative = -4.0_f32;
2044 /// let negative_zero = -0.0_f32;
2045 ///
2046 /// assert_eq!(f32::math::sqrt(positive), 2.0);
2047 /// assert!(f32::math::sqrt(negative).is_nan());
2048 /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
2049 /// ```
2050 ///
2051 /// _This standalone function is for testing only.
2052 /// It will be stabilized as an inherent method._
2053 ///
2054 /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
2055 #[inline]
2056 #[doc(alias = "squareRoot")]
2057 #[unstable(feature = "core_float_math", issue = "137578")]
2058 #[must_use = "method returns a new number and does not mutate the original value"]
2059 pub fn sqrt(x: f32) -> f32 {
2060 intrinsics::sqrtf32(x)
2061 }
2062
2063 /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
2064 ///
2065 /// # Examples
2066 ///
2067 /// ```
2068 /// #![feature(core_float_math)]
2069 ///
2070 /// use core::f32;
2071 ///
2072 /// let x = 3.0f32;
2073 /// let y = -3.0f32;
2074 ///
2075 /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
2076 /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
2077 ///
2078 /// assert!(abs_difference_x <= 1e-6);
2079 /// assert!(abs_difference_y <= 1e-6);
2080 /// ```
2081 ///
2082 /// _This standalone function is for testing only.
2083 /// It will be stabilized as an inherent method._
2084 ///
2085 /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
2086 #[inline]
2087 #[stable(feature = "rust1", since = "1.0.0")]
2088 #[deprecated(
2089 since = "1.10.0",
2090 note = "you probably meant `(self - other).abs()`: \
2091 this operation is `(self - other).max(0.0)` \
2092 except that `abs_sub` also propagates NaNs (also \
2093 known as `fdimf` in C). If you truly need the positive \
2094 difference, consider using that expression or the C function \
2095 `fdimf`, depending on how you wish to handle NaN (please consider \
2096 filing an issue describing your use-case too)."
2097 )]
2098 #[must_use = "method returns a new number and does not mutate the original value"]
2099 pub fn abs_sub(x: f32, other: f32) -> f32 {
2100 libm::fdimf(x, other)
2101 }
2102
2103 /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2104 ///
2105 /// # Unspecified precision
2106 ///
2107 /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2108 /// can even differ within the same execution from one invocation to the next.
2109 /// This function currently corresponds to the `cbrtf` from libc on Unix
2110 /// and Windows. Note that this might change in the future.
2111 ///
2112 /// # Examples
2113 ///
2114 /// ```
2115 /// #![feature(core_float_math)]
2116 ///
2117 /// use core::f32;
2118 ///
2119 /// let x = 8.0f32;
2120 ///
2121 /// // x^(1/3) - 2 == 0
2122 /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2123 ///
2124 /// assert!(abs_difference <= 1e-6);
2125 /// ```
2126 ///
2127 /// _This standalone function is for testing only.
2128 /// It will be stabilized as an inherent method._
2129 ///
2130 /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2131 #[inline]
2132 #[must_use = "method returns a new number and does not mutate the original value"]
2133 #[unstable(feature = "core_float_math", issue = "137578")]
2134 pub fn cbrt(x: f32) -> f32 {
2135 libm::cbrtf(x)
2136 }
2137}