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#![expect(clippy::approx_constant, reason = "this module defines f32 constants")]
14
15use crate::convert::{FloatToFloat, FloatToInt};
16use crate::num::FpCategory;
17use crate::panic::const_assert;
18use crate::{cfg_select, intrinsics, mem};
19
20/// The radix or base of the internal representation of `f32`.
21/// Use [`f32::RADIX`] instead.
22///
23/// # Examples
24///
25/// ```rust
26/// // deprecated way
27/// # #[allow(deprecated)]
28/// let r = std::f32::RADIX;
29///
30/// // intended way
31/// let r = f32::RADIX;
32/// ```
33#[stable(feature = "rust1", since = "1.0.0")]
34#[deprecated(since = "1.99.0", note = "replaced by the `RADIX` associated constant on `f32`")]
35#[rustc_diagnostic_item = "f32_legacy_const_radix"]
36pub const RADIX: u32 = f32::RADIX;
37
38/// Number of significant digits in base 2.
39/// Use [`f32::MANTISSA_DIGITS`] instead.
40///
41/// # Examples
42///
43/// ```rust
44/// // deprecated way
45/// # #[allow(deprecated)]
46/// let d = std::f32::MANTISSA_DIGITS;
47///
48/// // intended way
49/// let d = f32::MANTISSA_DIGITS;
50/// ```
51#[stable(feature = "rust1", since = "1.0.0")]
52#[deprecated(
53 since = "1.99.0",
54 note = "replaced by the `MANTISSA_DIGITS` associated constant on `f32`"
55)]
56#[rustc_diagnostic_item = "f32_legacy_const_mantissa_dig"]
57pub const MANTISSA_DIGITS: u32 = f32::MANTISSA_DIGITS;
58
59/// Approximate number of significant digits in base 10.
60/// Use [`f32::DIGITS`] instead.
61///
62/// # Examples
63///
64/// ```rust
65/// // deprecated way
66/// # #[allow(deprecated)]
67/// let d = std::f32::DIGITS;
68///
69/// // intended way
70/// let d = f32::DIGITS;
71/// ```
72#[stable(feature = "rust1", since = "1.0.0")]
73#[deprecated(since = "1.99.0", note = "replaced by the `DIGITS` associated constant on `f32`")]
74#[rustc_diagnostic_item = "f32_legacy_const_digits"]
75pub const DIGITS: u32 = f32::DIGITS;
76
77/// [Machine epsilon] value for `f32`.
78/// Use [`f32::EPSILON`] instead.
79///
80/// This is the difference between `1.0` and the next larger representable number.
81///
82/// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
83///
84/// # Examples
85///
86/// ```rust
87/// // deprecated way
88/// # #[allow(deprecated)]
89/// let e = std::f32::EPSILON;
90///
91/// // intended way
92/// let e = f32::EPSILON;
93/// ```
94#[stable(feature = "rust1", since = "1.0.0")]
95#[deprecated(since = "1.99.0", note = "replaced by the `EPSILON` associated constant on `f32`")]
96#[rustc_diagnostic_item = "f32_legacy_const_epsilon"]
97pub const EPSILON: f32 = f32::EPSILON;
98
99/// Smallest finite `f32` value.
100/// Use [`f32::MIN`] instead.
101///
102/// # Examples
103///
104/// ```rust
105/// // deprecated way
106/// # #[allow(deprecated)]
107/// let min = std::f32::MIN;
108///
109/// // intended way
110/// let min = f32::MIN;
111/// ```
112#[stable(feature = "rust1", since = "1.0.0")]
113#[deprecated(since = "1.99.0", note = "replaced by the `MIN` associated constant on `f32`")]
114#[rustc_diagnostic_item = "f32_legacy_const_min"]
115pub const MIN: f32 = f32::MIN;
116
117/// Smallest positive normal `f32` value.
118/// Use [`f32::MIN_POSITIVE`] instead.
119///
120/// # Examples
121///
122/// ```rust
123/// // deprecated way
124/// # #[allow(deprecated)]
125/// let min = std::f32::MIN_POSITIVE;
126///
127/// // intended way
128/// let min = f32::MIN_POSITIVE;
129/// ```
130#[stable(feature = "rust1", since = "1.0.0")]
131#[deprecated(
132 since = "1.99.0",
133 note = "replaced by the `MIN_POSITIVE` associated constant on `f32`"
134)]
135#[rustc_diagnostic_item = "f32_legacy_const_min_positive"]
136pub const MIN_POSITIVE: f32 = f32::MIN_POSITIVE;
137
138/// Largest finite `f32` value.
139/// Use [`f32::MAX`] instead.
140///
141/// # Examples
142///
143/// ```rust
144/// // deprecated way
145/// # #[allow(deprecated)]
146/// let max = std::f32::MAX;
147///
148/// // intended way
149/// let max = f32::MAX;
150/// ```
151#[stable(feature = "rust1", since = "1.0.0")]
152#[deprecated(since = "1.99.0", note = "replaced by the `MAX` associated constant on `f32`")]
153#[rustc_diagnostic_item = "f32_legacy_const_max"]
154pub const MAX: f32 = f32::MAX;
155
156/// One greater than the minimum possible normal power of 2 exponent.
157/// Use [`f32::MIN_EXP`] instead.
158///
159/// # Examples
160///
161/// ```rust
162/// // deprecated way
163/// # #[allow(deprecated)]
164/// let min = std::f32::MIN_EXP;
165///
166/// // intended way
167/// let min = f32::MIN_EXP;
168/// ```
169#[stable(feature = "rust1", since = "1.0.0")]
170#[deprecated(since = "1.99.0", note = "replaced by the `MIN_EXP` associated constant on `f32`")]
171#[rustc_diagnostic_item = "f32_legacy_const_min_exp"]
172pub const MIN_EXP: i32 = f32::MIN_EXP;
173
174/// Maximum possible power of 2 exponent.
175/// Use [`f32::MAX_EXP`] instead.
176///
177/// # Examples
178///
179/// ```rust
180/// // deprecated way
181/// # #[allow(deprecated)]
182/// let max = std::f32::MAX_EXP;
183///
184/// // intended way
185/// let max = f32::MAX_EXP;
186/// ```
187#[stable(feature = "rust1", since = "1.0.0")]
188#[deprecated(since = "1.99.0", note = "replaced by the `MAX_EXP` associated constant on `f32`")]
189#[rustc_diagnostic_item = "f32_legacy_const_max_exp"]
190pub const MAX_EXP: i32 = f32::MAX_EXP;
191
192/// Minimum possible normal power of 10 exponent.
193/// Use [`f32::MIN_10_EXP`] instead.
194///
195/// # Examples
196///
197/// ```rust
198/// // deprecated way
199/// # #[allow(deprecated)]
200/// let min = std::f32::MIN_10_EXP;
201///
202/// // intended way
203/// let min = f32::MIN_10_EXP;
204/// ```
205#[stable(feature = "rust1", since = "1.0.0")]
206#[deprecated(since = "1.99.0", note = "replaced by the `MIN_10_EXP` associated constant on `f32`")]
207#[rustc_diagnostic_item = "f32_legacy_const_min_10_exp"]
208pub const MIN_10_EXP: i32 = f32::MIN_10_EXP;
209
210/// Maximum possible power of 10 exponent.
211/// Use [`f32::MAX_10_EXP`] instead.
212///
213/// # Examples
214///
215/// ```rust
216/// // deprecated way
217/// # #[allow(deprecated)]
218/// let max = std::f32::MAX_10_EXP;
219///
220/// // intended way
221/// let max = f32::MAX_10_EXP;
222/// ```
223#[stable(feature = "rust1", since = "1.0.0")]
224#[deprecated(since = "1.99.0", note = "replaced by the `MAX_10_EXP` associated constant on `f32`")]
225#[rustc_diagnostic_item = "f32_legacy_const_max_10_exp"]
226pub const MAX_10_EXP: i32 = f32::MAX_10_EXP;
227
228/// Not a Number (NaN).
229/// Use [`f32::NAN`] instead.
230///
231/// # Examples
232///
233/// ```rust
234/// // deprecated way
235/// # #[allow(deprecated)]
236/// let nan = std::f32::NAN;
237///
238/// // intended way
239/// let nan = f32::NAN;
240/// ```
241#[stable(feature = "rust1", since = "1.0.0")]
242#[deprecated(since = "1.99.0", note = "replaced by the `NAN` associated constant on `f32`")]
243#[rustc_diagnostic_item = "f32_legacy_const_nan"]
244pub const NAN: f32 = f32::NAN;
245
246/// Infinity (∞).
247/// Use [`f32::INFINITY`] instead.
248///
249/// # Examples
250///
251/// ```rust
252/// // deprecated way
253/// # #[allow(deprecated)]
254/// let inf = std::f32::INFINITY;
255///
256/// // intended way
257/// let inf = f32::INFINITY;
258/// ```
259#[stable(feature = "rust1", since = "1.0.0")]
260#[deprecated(since = "1.99.0", note = "replaced by the `INFINITY` associated constant on `f32`")]
261#[rustc_diagnostic_item = "f32_legacy_const_infinity"]
262pub const INFINITY: f32 = f32::INFINITY;
263
264/// Negative infinity (−∞).
265/// Use [`f32::NEG_INFINITY`] instead.
266///
267/// # Examples
268///
269/// ```rust
270/// // deprecated way
271/// # #[allow(deprecated)]
272/// let ninf = std::f32::NEG_INFINITY;
273///
274/// // intended way
275/// let ninf = f32::NEG_INFINITY;
276/// ```
277#[stable(feature = "rust1", since = "1.0.0")]
278#[deprecated(
279 since = "1.99.0",
280 note = "replaced by the `NEG_INFINITY` associated constant on `f32`"
281)]
282#[rustc_diagnostic_item = "f32_legacy_const_neg_infinity"]
283pub const NEG_INFINITY: f32 = f32::NEG_INFINITY;
284
285/// Basic mathematical constants.
286#[stable(feature = "rust1", since = "1.0.0")]
287#[rustc_diagnostic_item = "f32_consts_mod"]
288pub mod consts {
289 // FIXME: replace with mathematical constants from cmath.
290
291 /// Archimedes' constant (π)
292 #[stable(feature = "rust1", since = "1.0.0")]
293 pub const PI: f32 = 3.14159265358979323846264338327950288_f32;
294
295 /// The full circle constant (τ)
296 ///
297 /// Equal to 2π.
298 #[stable(feature = "tau_constant", since = "1.47.0")]
299 pub const TAU: f32 = 6.28318530717958647692528676655900577_f32;
300
301 /// The golden ratio (φ)
302 #[doc(alias = "phi")]
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
404#[doc(test(attr(allow(unused_features))))]
405impl f32 {
406 /// The radix or base of the internal representation of `f32`.
407 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
408 pub const RADIX: u32 = 2;
409
410 /// The size of this float type in bits.
411 #[unstable(feature = "float_bits_const", issue = "151073")]
412 pub const BITS: u32 = 32;
413
414 /// Number of significant digits in base 2.
415 ///
416 /// Note that the size of the mantissa in the bitwise representation is one
417 /// smaller than this since the leading 1 is not stored explicitly.
418 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
419 pub const MANTISSA_DIGITS: u32 = 24;
420
421 /// Approximate number of significant digits in base 10.
422 ///
423 /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
424 /// significant digits can be converted to `f32` and back without loss.
425 ///
426 /// Equal to floor(log<sub>10</sub> 2<sup>[`MANTISSA_DIGITS`] − 1</sup>).
427 ///
428 /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
429 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
430 pub const DIGITS: u32 = 6;
431
432 /// [Machine epsilon] value for `f32`.
433 ///
434 /// This is the difference between `1.0` and the next larger representable number.
435 ///
436 /// Equal to 2<sup>1 − [`MANTISSA_DIGITS`]</sup>.
437 ///
438 /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
439 /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
440 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
441 #[rustc_diagnostic_item = "f32_epsilon"]
442 pub const EPSILON: f32 = 1.1920929e-07_f32;
443
444 /// Smallest finite `f32` value.
445 ///
446 /// Equal to −[`MAX`].
447 ///
448 /// [`MAX`]: f32::MAX
449 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
450 pub const MIN: f32 = -3.4028235e+38_f32;
451 /// Smallest positive normal `f32` value.
452 ///
453 /// Equal to 2<sup>[`MIN_EXP`] − 1</sup>.
454 ///
455 /// [`MIN_EXP`]: f32::MIN_EXP
456 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
457 pub const MIN_POSITIVE: f32 = 1.1754944e-38_f32;
458 /// Largest finite `f32` value.
459 ///
460 /// Equal to
461 /// (1 − 2<sup>−[`MANTISSA_DIGITS`]</sup>) 2<sup>[`MAX_EXP`]</sup>.
462 ///
463 /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
464 /// [`MAX_EXP`]: f32::MAX_EXP
465 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
466 pub const MAX: f32 = 3.4028235e+38_f32;
467
468 /// One greater than the minimum possible *normal* power of 2 exponent
469 /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
470 ///
471 /// This corresponds to the exact minimum possible *normal* power of 2 exponent
472 /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
473 /// In other words, all normal numbers representable by this type are
474 /// greater than or equal to 0.5 × 2<sup><i>MIN_EXP</i></sup>.
475 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
476 pub const MIN_EXP: i32 = -125;
477 /// One greater than the maximum possible power of 2 exponent
478 /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
479 ///
480 /// This corresponds to the exact maximum possible power of 2 exponent
481 /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
482 /// In other words, all numbers representable by this type are
483 /// strictly less than 2<sup><i>MAX_EXP</i></sup>.
484 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
485 pub const MAX_EXP: i32 = 128;
486
487 /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
488 ///
489 /// Equal to ceil(log<sub>10</sub> [`MIN_POSITIVE`]).
490 ///
491 /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
492 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
493 pub const MIN_10_EXP: i32 = -37;
494 /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
495 ///
496 /// Equal to floor(log<sub>10</sub> [`MAX`]).
497 ///
498 /// [`MAX`]: f32::MAX
499 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
500 pub const MAX_10_EXP: i32 = 38;
501
502 /// Not a Number (NaN).
503 ///
504 /// Note that IEEE 754 doesn't define just a single NaN value; a plethora of bit patterns are
505 /// considered to be NaN. Furthermore, the standard makes a difference between a "signaling" and
506 /// a "quiet" NaN, and allows inspecting its "payload" (the unspecified bits in the bit pattern)
507 /// and its sign. See the [specification of NaN bit patterns](f32#nan-bit-patterns) for more
508 /// info.
509 ///
510 /// This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions
511 /// that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is
512 /// guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary.
513 /// The concrete bit pattern may change across Rust versions and target platforms.
514 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
515 #[rustc_diagnostic_item = "f32_nan"]
516 #[allow(clippy::eq_op, clippy::zero_divided_by_zero)]
517 pub const NAN: f32 = 0.0_f32 / 0.0_f32;
518 /// Infinity (∞).
519 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
520 pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
521 /// Negative infinity (−∞).
522 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
523 pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
524
525 /// Maximum integer that can be represented exactly in an [`f32`] value,
526 /// with no other integer converting to the same floating point value.
527 ///
528 /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
529 /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
530 /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
531 /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
532 /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
533 /// "one-to-one" mapping.
534 ///
535 /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
536 /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
537 /// ```
538 /// #![feature(float_exact_integer_constants)]
539 /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
540 /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
541 /// let max_exact_int = f32::MAX_EXACT_INTEGER;
542 /// assert_eq!(max_exact_int, max_exact_int as f32 as i32);
543 /// assert_eq!(max_exact_int + 1, (max_exact_int + 1) as f32 as i32);
544 /// assert_ne!(max_exact_int + 2, (max_exact_int + 2) as f32 as i32);
545 ///
546 /// // Beyond `f32::MAX_EXACT_INTEGER`, multiple integers can map to one float value
547 /// assert_eq!((max_exact_int + 1) as f32, (max_exact_int + 2) as f32);
548 /// # }
549 /// ```
550 #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
551 pub const MAX_EXACT_INTEGER: i32 = (1 << Self::MANTISSA_DIGITS) - 1;
552
553 /// Minimum integer that can be represented exactly in an [`f32`] value,
554 /// with no other integer converting to the same floating point value.
555 ///
556 /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
557 /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
558 /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
559 /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
560 /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
561 /// "one-to-one" mapping.
562 ///
563 /// This constant is equivalent to `-MAX_EXACT_INTEGER`.
564 ///
565 /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
566 /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
567 /// ```
568 /// #![feature(float_exact_integer_constants)]
569 /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
570 /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
571 /// let min_exact_int = f32::MIN_EXACT_INTEGER;
572 /// assert_eq!(min_exact_int, min_exact_int as f32 as i32);
573 /// assert_eq!(min_exact_int - 1, (min_exact_int - 1) as f32 as i32);
574 /// assert_ne!(min_exact_int - 2, (min_exact_int - 2) as f32 as i32);
575 ///
576 /// // Below `f32::MIN_EXACT_INTEGER`, multiple integers can map to one float value
577 /// assert_eq!((min_exact_int - 1) as f32, (min_exact_int - 2) as f32);
578 /// # }
579 /// ```
580 #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
581 pub const MIN_EXACT_INTEGER: i32 = -Self::MAX_EXACT_INTEGER;
582
583 /// The mask of the bit used to encode the sign of an [`f32`].
584 ///
585 /// This bit is set when the sign is negative and unset when the sign is
586 /// positive.
587 /// If you only need to check whether a value is positive or negative,
588 /// [`is_sign_positive`] or [`is_sign_negative`] can be used.
589 ///
590 /// [`is_sign_positive`]: f32::is_sign_positive
591 /// [`is_sign_negative`]: f32::is_sign_negative
592 /// ```rust
593 /// #![feature(float_masks)]
594 /// let sign_mask = f32::SIGN_MASK;
595 /// let a = 1.6552f32;
596 /// let a_bits = a.to_bits();
597 ///
598 /// assert_eq!(a_bits & sign_mask, 0x0);
599 /// assert_eq!(f32::from_bits(a_bits ^ sign_mask), -a);
600 /// assert_eq!(sign_mask, (-0.0f32).to_bits());
601 /// ```
602 #[unstable(feature = "float_masks", issue = "154064")]
603 pub const SIGN_MASK: u32 = 0x8000_0000;
604
605 /// The mask of the bits used to encode the exponent of an [`f32`].
606 ///
607 /// Note that the exponent is stored as a biased value, with a bias of 127 for `f32`.
608 ///
609 /// ```rust
610 /// #![feature(float_masks)]
611 /// fn get_exp(a: f32) -> i32 {
612 /// let bias = 127;
613 /// let biased = a.to_bits() & f32::EXPONENT_MASK;
614 /// (biased >> (f32::MANTISSA_DIGITS - 1)).cast_signed() - bias
615 /// }
616 ///
617 /// assert_eq!(get_exp(0.5), -1);
618 /// assert_eq!(get_exp(1.0), 0);
619 /// assert_eq!(get_exp(2.0), 1);
620 /// assert_eq!(get_exp(4.0), 2);
621 /// ```
622 #[unstable(feature = "float_masks", issue = "154064")]
623 pub const EXPONENT_MASK: u32 = 0x7f80_0000;
624
625 /// The mask of the bits used to encode the mantissa of an [`f32`].
626 ///
627 /// ```rust
628 /// #![feature(float_masks)]
629 /// let mantissa_mask = f32::MANTISSA_MASK;
630 ///
631 /// assert_eq!(0f32.to_bits() & mantissa_mask, 0x0);
632 /// assert_eq!(1f32.to_bits() & mantissa_mask, 0x0);
633 ///
634 /// // multiplying a finite value by a power of 2 doesn't change its mantissa
635 /// // unless the result or initial value is not normal.
636 /// let a = 1.6552f32;
637 /// let b = 4.0 * a;
638 /// assert_eq!(a.to_bits() & mantissa_mask, b.to_bits() & mantissa_mask);
639 ///
640 /// // The maximum and minimum values have a saturated significand
641 /// assert_eq!(f32::MAX.to_bits() & f32::MANTISSA_MASK, f32::MANTISSA_MASK);
642 /// assert_eq!(f32::MIN.to_bits() & f32::MANTISSA_MASK, f32::MANTISSA_MASK);
643 /// ```
644 #[unstable(feature = "float_masks", issue = "154064")]
645 pub const MANTISSA_MASK: u32 = 0x007f_ffff;
646
647 /// Minimum representable positive value (min subnormal)
648 const TINY_BITS: u32 = 0x1;
649
650 /// Minimum representable negative value (min negative subnormal)
651 const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
652
653 /// Returns `true` if this value is NaN.
654 ///
655 /// ```
656 /// let nan = f32::NAN;
657 /// let f = 7.0_f32;
658 ///
659 /// assert!(nan.is_nan());
660 /// assert!(!f.is_nan());
661 /// ```
662 #[must_use]
663 #[stable(feature = "rust1", since = "1.0.0")]
664 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
665 #[inline]
666 #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
667 #[ferrocene::prevalidated]
668 pub const fn is_nan(self) -> bool {
669 self != self
670 }
671
672 /// Returns `true` if this value is positive infinity or negative infinity, and
673 /// `false` otherwise.
674 ///
675 /// ```
676 /// let f = 7.0f32;
677 /// let inf = f32::INFINITY;
678 /// let neg_inf = f32::NEG_INFINITY;
679 /// let nan = f32::NAN;
680 ///
681 /// assert!(!f.is_infinite());
682 /// assert!(!nan.is_infinite());
683 ///
684 /// assert!(inf.is_infinite());
685 /// assert!(neg_inf.is_infinite());
686 /// ```
687 #[must_use]
688 #[stable(feature = "rust1", since = "1.0.0")]
689 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
690 #[inline]
691 #[ferrocene::prevalidated]
692 pub const fn is_infinite(self) -> bool {
693 // Getting clever with transmutation can result in incorrect answers on some FPUs
694 // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
695 // See https://github.com/rust-lang/rust/issues/72327
696 (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
697 }
698
699 /// Returns `true` if this number is neither infinite nor NaN.
700 ///
701 /// ```
702 /// let f = 7.0f32;
703 /// let inf = f32::INFINITY;
704 /// let neg_inf = f32::NEG_INFINITY;
705 /// let nan = f32::NAN;
706 ///
707 /// assert!(f.is_finite());
708 ///
709 /// assert!(!nan.is_finite());
710 /// assert!(!inf.is_finite());
711 /// assert!(!neg_inf.is_finite());
712 /// ```
713 #[must_use]
714 #[stable(feature = "rust1", since = "1.0.0")]
715 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
716 #[inline]
717 pub const fn is_finite(self) -> bool {
718 // There's no need to handle NaN separately: if self is NaN,
719 // the comparison is not true, exactly as desired.
720 self.abs() < Self::INFINITY
721 }
722
723 /// Returns `true` if the number is [subnormal].
724 ///
725 /// ```
726 /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
727 /// let max = f32::MAX;
728 /// let lower_than_min = 1.0e-40_f32;
729 /// let zero = 0.0_f32;
730 ///
731 /// assert!(!min.is_subnormal());
732 /// assert!(!max.is_subnormal());
733 ///
734 /// assert!(!zero.is_subnormal());
735 /// assert!(!f32::NAN.is_subnormal());
736 /// assert!(!f32::INFINITY.is_subnormal());
737 /// // Values between `0` and `min` are Subnormal.
738 /// assert!(lower_than_min.is_subnormal());
739 /// ```
740 /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
741 #[must_use]
742 #[stable(feature = "is_subnormal", since = "1.53.0")]
743 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
744 #[inline]
745 pub const fn is_subnormal(self) -> bool {
746 matches!(self.classify(), FpCategory::Subnormal)
747 }
748
749 /// Returns `true` if the number is neither zero, infinite,
750 /// [subnormal], or NaN.
751 ///
752 /// ```
753 /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
754 /// let max = f32::MAX;
755 /// let lower_than_min = 1.0e-40_f32;
756 /// let zero = 0.0_f32;
757 ///
758 /// assert!(min.is_normal());
759 /// assert!(max.is_normal());
760 ///
761 /// assert!(!zero.is_normal());
762 /// assert!(!f32::NAN.is_normal());
763 /// assert!(!f32::INFINITY.is_normal());
764 /// // Values between `0` and `min` are Subnormal.
765 /// assert!(!lower_than_min.is_normal());
766 /// ```
767 /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
768 #[must_use]
769 #[stable(feature = "rust1", since = "1.0.0")]
770 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
771 #[inline]
772 pub const fn is_normal(self) -> bool {
773 matches!(self.classify(), FpCategory::Normal)
774 }
775
776 /// Returns the floating point category of the number. If only one property
777 /// is going to be tested, it is generally faster to use the specific
778 /// predicate instead.
779 ///
780 /// ```
781 /// use std::num::FpCategory;
782 ///
783 /// let num = 12.4_f32;
784 /// let inf = f32::INFINITY;
785 ///
786 /// assert_eq!(num.classify(), FpCategory::Normal);
787 /// assert_eq!(inf.classify(), FpCategory::Infinite);
788 /// ```
789 #[ferrocene::prevalidated]
790 #[stable(feature = "rust1", since = "1.0.0")]
791 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
792 #[must_use]
793 pub const fn classify(self) -> FpCategory {
794 // We used to have complicated logic here that avoids the simple bit-based tests to work
795 // around buggy codegen for x87 targets (see
796 // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
797 // of our tests is able to find any difference between the complicated and the naive
798 // version, so now we are back to the naive version.
799 let b = self.to_bits();
800 match (b & Self::MANTISSA_MASK, b & Self::EXPONENT_MASK) {
801 (0, Self::EXPONENT_MASK) => FpCategory::Infinite,
802 (_, Self::EXPONENT_MASK) => FpCategory::Nan,
803 (0, 0) => FpCategory::Zero,
804 (_, 0) => FpCategory::Subnormal,
805 _ => FpCategory::Normal,
806 }
807 }
808
809 /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
810 /// positive sign bit and positive infinity.
811 ///
812 /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
813 /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
814 /// conserved over arithmetic operations, the result of `is_sign_positive` on
815 /// a NaN might produce an unexpected or non-portable result. See the [specification
816 /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
817 /// if you need fully portable behavior (will return NaN for all NaNs).
818 ///
819 /// ```
820 /// let f = 7.0_f32;
821 /// let g = -7.0_f32;
822 ///
823 /// assert!(f.is_sign_positive());
824 /// assert!(!g.is_sign_positive());
825 /// ```
826 #[must_use]
827 #[stable(feature = "rust1", since = "1.0.0")]
828 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
829 #[inline]
830 pub const fn is_sign_positive(self) -> bool {
831 !self.is_sign_negative()
832 }
833
834 /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
835 /// negative sign bit and negative infinity.
836 ///
837 /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
838 /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
839 /// conserved over arithmetic operations, the result of `is_sign_negative` on
840 /// a NaN might produce an unexpected or non-portable result. See the [specification
841 /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
842 /// if you need fully portable behavior (will return NaN for all NaNs).
843 ///
844 /// ```
845 /// let f = 7.0f32;
846 /// let g = -7.0f32;
847 ///
848 /// assert!(!f.is_sign_negative());
849 /// assert!(g.is_sign_negative());
850 /// ```
851 #[must_use]
852 #[stable(feature = "rust1", since = "1.0.0")]
853 #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
854 #[inline]
855 #[ferrocene::prevalidated]
856 pub const fn is_sign_negative(self) -> bool {
857 // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
858 // applies to zeros and NaNs as well.
859 self.to_bits() & 0x8000_0000 != 0
860 }
861
862 /// Returns the least number greater than `self`.
863 ///
864 /// Let `TINY` be the smallest representable positive `f32`. Then,
865 /// - if `self.is_nan()`, this returns `self`;
866 /// - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
867 /// - if `self` is `-TINY`, this returns -0.0;
868 /// - if `self` is -0.0 or +0.0, this returns `TINY`;
869 /// - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
870 /// - otherwise the unique least value greater than `self` is returned.
871 ///
872 /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
873 /// is finite `x == x.next_up().next_down()` also holds.
874 ///
875 /// ```rust
876 /// // f32::EPSILON is the difference between 1.0 and the next number up.
877 /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
878 /// // But not for most numbers.
879 /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
880 /// assert_eq!(16777216f32.next_up(), 16777218.0);
881 /// ```
882 ///
883 /// This operation corresponds to IEEE-754 `nextUp`.
884 ///
885 /// [`NEG_INFINITY`]: Self::NEG_INFINITY
886 /// [`INFINITY`]: Self::INFINITY
887 /// [`MIN`]: Self::MIN
888 /// [`MAX`]: Self::MAX
889 #[inline]
890 #[doc(alias = "nextUp")]
891 #[stable(feature = "float_next_up_down", since = "1.86.0")]
892 #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
893 #[must_use = "method returns a new number and does not mutate the original value"]
894 pub const fn next_up(self) -> Self {
895 // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
896 // denormals to zero. This is in general unsound and unsupported, but here
897 // we do our best to still produce the correct result on such targets.
898 let bits = self.to_bits();
899 if self.is_nan() || bits == Self::INFINITY.to_bits() {
900 return self;
901 }
902
903 let abs = bits & !Self::SIGN_MASK;
904 let next_bits = if abs == 0 {
905 Self::TINY_BITS
906 } else if bits == abs {
907 bits + 1
908 } else {
909 bits - 1
910 };
911 Self::from_bits(next_bits)
912 }
913
914 /// Returns the greatest number less than `self`.
915 ///
916 /// Let `TINY` be the smallest representable positive `f32`. Then,
917 /// - if `self.is_nan()`, this returns `self`;
918 /// - if `self` is [`INFINITY`], this returns [`MAX`];
919 /// - if `self` is `TINY`, this returns 0.0;
920 /// - if `self` is -0.0 or +0.0, this returns `-TINY`;
921 /// - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
922 /// - otherwise the unique greatest value less than `self` is returned.
923 ///
924 /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
925 /// is finite `x == x.next_down().next_up()` also holds.
926 ///
927 /// ```rust
928 /// let x = 1.0f32;
929 /// // Clamp value into range [0, 1).
930 /// let clamped = x.clamp(0.0, 1.0f32.next_down());
931 /// assert!(clamped < 1.0);
932 /// assert_eq!(clamped.next_up(), 1.0);
933 /// ```
934 ///
935 /// This operation corresponds to IEEE-754 `nextDown`.
936 ///
937 /// [`NEG_INFINITY`]: Self::NEG_INFINITY
938 /// [`INFINITY`]: Self::INFINITY
939 /// [`MIN`]: Self::MIN
940 /// [`MAX`]: Self::MAX
941 #[inline]
942 #[doc(alias = "nextDown")]
943 #[stable(feature = "float_next_up_down", since = "1.86.0")]
944 #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
945 #[must_use = "method returns a new number and does not mutate the original value"]
946 pub const fn next_down(self) -> Self {
947 // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
948 // denormals to zero. This is in general unsound and unsupported, but here
949 // we do our best to still produce the correct result on such targets.
950 let bits = self.to_bits();
951 if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
952 return self;
953 }
954
955 let abs = bits & !Self::SIGN_MASK;
956 let next_bits = if abs == 0 {
957 Self::NEG_TINY_BITS
958 } else if bits == abs {
959 bits - 1
960 } else {
961 bits + 1
962 };
963 Self::from_bits(next_bits)
964 }
965
966 /// Takes the reciprocal (inverse) of a number, `1/x`.
967 ///
968 /// ```
969 /// let x = 2.0_f32;
970 /// let abs_difference = (x.recip() - (1.0 / x)).abs();
971 ///
972 /// assert!(abs_difference <= f32::EPSILON);
973 /// ```
974 #[must_use = "this returns the result of the operation, without modifying the original"]
975 #[stable(feature = "rust1", since = "1.0.0")]
976 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
977 #[inline]
978 pub const fn recip(self) -> f32 {
979 1.0 / self
980 }
981
982 /// Converts radians to degrees.
983 ///
984 /// # Unspecified precision
985 ///
986 /// The precision of this function is non-deterministic. This means it varies by platform,
987 /// Rust version, and can even differ within the same execution from one invocation to the next.
988 ///
989 /// # Examples
990 ///
991 /// ```
992 /// let angle = std::f32::consts::PI;
993 ///
994 /// let abs_difference = (angle.to_degrees() - 180.0).abs();
995 /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
996 /// assert!(abs_difference <= f32::EPSILON);
997 /// ```
998 #[must_use = "this returns the result of the operation, \
999 without modifying the original"]
1000 #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
1001 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1002 #[inline]
1003 pub const fn to_degrees(self) -> f32 {
1004 // Use a literal to avoid double rounding, consts::PI is already rounded,
1005 // and dividing would round again.
1006 const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
1007 self * PIS_IN_180
1008 }
1009
1010 /// Converts degrees to radians.
1011 ///
1012 /// # Unspecified precision
1013 ///
1014 /// The precision of this function is non-deterministic. This means it varies by platform,
1015 /// Rust version, and can even differ within the same execution from one invocation to the next.
1016 ///
1017 /// # Examples
1018 ///
1019 /// ```
1020 /// let angle = 180.0f32;
1021 ///
1022 /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
1023 ///
1024 /// assert!(abs_difference <= f32::EPSILON);
1025 /// ```
1026 #[must_use = "this returns the result of the operation, \
1027 without modifying the original"]
1028 #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
1029 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1030 #[inline]
1031 pub const fn to_radians(self) -> f32 {
1032 // The division here is correctly rounded with respect to the true value of π/180.
1033 // Although π is irrational and already rounded, the double rounding happens
1034 // to produce correct result for f32.
1035 const RADS_PER_DEG: f32 = consts::PI / 180.0;
1036 self * RADS_PER_DEG
1037 }
1038
1039 /// Returns the maximum of the two numbers, ignoring NaN.
1040 ///
1041 /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
1042 /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1043 /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1044 /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1045 /// non-deterministically.
1046 ///
1047 /// The handling of NaNs follows the IEEE 754-2019 semantics for `maximumNumber`, treating all
1048 /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1049 /// follows the IEEE 754-2008 semantics for `maxNum`.
1050 ///
1051 /// ```
1052 /// let x = 1.0f32;
1053 /// let y = 2.0f32;
1054 ///
1055 /// assert_eq!(x.max(y), y);
1056 /// assert_eq!(x.max(f32::NAN), x);
1057 /// ```
1058 #[must_use = "this returns the result of the comparison, without modifying either input"]
1059 #[stable(feature = "rust1", since = "1.0.0")]
1060 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1061 #[inline]
1062 #[ferrocene::prevalidated]
1063 pub const fn max(self, other: f32) -> f32 {
1064 intrinsics::maximum_number_nsz_f32(self, other)
1065 }
1066
1067 /// Returns the minimum of the two numbers, ignoring NaN.
1068 ///
1069 /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
1070 /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1071 /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1072 /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1073 /// non-deterministically.
1074 ///
1075 /// The handling of NaNs follows the IEEE 754-2019 semantics for `minimumNumber`, treating all
1076 /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1077 /// follows the IEEE 754-2008 semantics for `minNum`.
1078 ///
1079 /// ```
1080 /// let x = 1.0f32;
1081 /// let y = 2.0f32;
1082 ///
1083 /// assert_eq!(x.min(y), x);
1084 /// assert_eq!(x.min(f32::NAN), x);
1085 /// ```
1086 #[must_use = "this returns the result of the comparison, without modifying either input"]
1087 #[stable(feature = "rust1", since = "1.0.0")]
1088 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1089 #[inline]
1090 #[ferrocene::prevalidated]
1091 pub const fn min(self, other: f32) -> f32 {
1092 intrinsics::minimum_number_nsz_f32(self, other)
1093 }
1094
1095 /// Returns the maximum of the two numbers, propagating NaN.
1096 ///
1097 /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1098 /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1099 /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1100 /// non-NaN inputs.
1101 ///
1102 /// This is in contrast to [`f32::max`] which only returns NaN when *both* arguments are NaN,
1103 /// and which does not reliably order `-0.0` and `+0.0`.
1104 ///
1105 /// This follows the IEEE 754-2019 semantics for `maximum`.
1106 ///
1107 /// ```
1108 /// #![feature(float_minimum_maximum)]
1109 /// let x = 1.0f32;
1110 /// let y = 2.0f32;
1111 ///
1112 /// assert_eq!(x.maximum(y), y);
1113 /// assert!(x.maximum(f32::NAN).is_nan());
1114 /// ```
1115 #[must_use = "this returns the result of the comparison, without modifying either input"]
1116 #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1117 #[inline]
1118 pub const fn maximum(self, other: f32) -> f32 {
1119 intrinsics::maximumf32(self, other)
1120 }
1121
1122 /// Returns the minimum of the two numbers, propagating NaN.
1123 ///
1124 /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1125 /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1126 /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1127 /// non-NaN inputs.
1128 ///
1129 /// This is in contrast to [`f32::min`] which only returns NaN when *both* arguments are NaN,
1130 /// and which does not reliably order `-0.0` and `+0.0`.
1131 ///
1132 /// This follows the IEEE 754-2019 semantics for `minimum`.
1133 ///
1134 /// ```
1135 /// #![feature(float_minimum_maximum)]
1136 /// let x = 1.0f32;
1137 /// let y = 2.0f32;
1138 ///
1139 /// assert_eq!(x.minimum(y), x);
1140 /// assert!(x.minimum(f32::NAN).is_nan());
1141 /// ```
1142 #[must_use = "this returns the result of the comparison, without modifying either input"]
1143 #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1144 #[inline]
1145 pub const fn minimum(self, other: f32) -> f32 {
1146 intrinsics::minimumf32(self, other)
1147 }
1148
1149 /// Calculates the midpoint (average) between `self` and `rhs`.
1150 ///
1151 /// This returns NaN when *either* argument is NaN or if a combination of
1152 /// +inf and -inf is provided as arguments.
1153 ///
1154 /// # Examples
1155 ///
1156 /// ```
1157 /// assert_eq!(1f32.midpoint(4.0), 2.5);
1158 /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1159 /// ```
1160 #[inline]
1161 #[doc(alias = "average")]
1162 #[stable(feature = "num_midpoint", since = "1.85.0")]
1163 #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1164 #[must_use = "this returns the result of the operation, \
1165 without modifying the original"]
1166 pub const fn midpoint(self, other: f32) -> f32 {
1167 cfg_select! {
1168 // Allow faster implementation that have known good 64-bit float
1169 // implementations. Falling back to the branchy code on targets that don't
1170 // have 64-bit hardware floats or buggy implementations.
1171 // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1172 any(
1173 target_arch = "x86_64",
1174 target_arch = "aarch64",
1175 all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1176 all(target_arch = "loongarch64", target_feature = "d"),
1177 all(target_arch = "arm", target_feature = "vfp2"),
1178 target_arch = "wasm32",
1179 target_arch = "wasm64",
1180 ) => ((self as f64 + other as f64) * 0.5) as f32,
1181 _ => {
1182 const HI: f32 = f32::MAX * 0.5;
1183
1184 let (a, b) = (self, other);
1185 let abs_a = a.abs();
1186 let abs_b = b.abs();
1187
1188 if abs_a <= HI && abs_b <= HI {
1189 // Overflow is impossible
1190 (a + b) * 0.5
1191 } else {
1192 (a * 0.5) + (b * 0.5)
1193 }
1194 }
1195 }
1196 }
1197
1198 /// Rounds toward zero and converts to any primitive integer type,
1199 /// assuming that the value is finite and fits in that type.
1200 ///
1201 /// ```
1202 /// let value = 4.6_f32;
1203 /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1204 /// assert_eq!(rounded, 4);
1205 ///
1206 /// let value = -128.9_f32;
1207 /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1208 /// assert_eq!(rounded, i8::MIN);
1209 /// ```
1210 ///
1211 /// # Safety
1212 ///
1213 /// The value must:
1214 ///
1215 /// * Not be `NaN`
1216 /// * Not be infinite
1217 /// * Be representable in the return type `Int`, after truncating off its fractional part
1218 #[must_use = "this returns the result of the operation, \
1219 without modifying the original"]
1220 #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1221 #[inline]
1222 pub unsafe fn to_int_unchecked<Int>(self) -> Int
1223 where
1224 Self: FloatToInt<Int>,
1225 {
1226 // SAFETY: the caller must uphold the safety contract for
1227 // `FloatToInt::to_int_unchecked`.
1228 unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1229 }
1230
1231 /// Converts to the target float type, rounding as defined in IEEE 754.
1232 ///
1233 /// This is equivalent to `self as Flt`. Narrowing to a smaller type can
1234 /// produce an infinity.
1235 ///
1236 /// ```
1237 /// #![feature(float_conversions)]
1238 ///
1239 /// let x = 1.5_f32;
1240 /// assert_eq!(x.cast::<f64>(), 1.5_f64);
1241 /// ```
1242 #[unstable(feature = "float_conversions", issue = "159913")]
1243 #[must_use = "this returns the result of the operation, \
1244 without modifying the original"]
1245 #[inline]
1246 pub fn cast<Flt>(self) -> Flt
1247 where
1248 Self: FloatToFloat<Flt>,
1249 {
1250 FloatToFloat::<Flt>::cast(self)
1251 }
1252
1253 /// Rounds toward zero and converts to any primitive integer type, saturating
1254 /// at the type's boundaries and mapping `NaN` to zero.
1255 ///
1256 /// This is equivalent to `self as Int`.
1257 ///
1258 /// ```
1259 /// #![feature(float_conversions)]
1260 ///
1261 /// assert_eq!(255.5_f32.to_int_saturating::<u8>(), 255);
1262 /// assert_eq!(300.0_f32.to_int_saturating::<u8>(), 255);
1263 /// assert_eq!((-1.0_f32).to_int_saturating::<u8>(), 0);
1264 /// assert_eq!(f32::NAN.to_int_saturating::<u8>(), 0);
1265 /// ```
1266 #[unstable(feature = "float_conversions", issue = "159913")]
1267 #[must_use = "this returns the result of the operation, \
1268 without modifying the original"]
1269 #[inline]
1270 pub fn to_int_saturating<Int>(self) -> Int
1271 where
1272 Self: FloatToInt<Int>,
1273 {
1274 FloatToInt::<Int>::to_int_saturating(self)
1275 }
1276
1277 /// Rounds toward zero and converts to any primitive integer type, returning
1278 /// `None` if the value is `NaN`, infinite, or does not fit in the target type.
1279 ///
1280 /// ```
1281 /// #![feature(float_conversions)]
1282 ///
1283 /// assert_eq!(255.5_f32.to_int_checked::<u8>(), Some(255));
1284 /// assert_eq!(256.0_f32.to_int_checked::<u8>(), None);
1285 /// assert_eq!(f32::NAN.to_int_checked::<u8>(), None);
1286 /// ```
1287 #[unstable(feature = "float_conversions", issue = "159913")]
1288 #[must_use = "this returns the result of the operation, \
1289 without modifying the original"]
1290 #[inline]
1291 pub fn to_int_checked<Int>(self) -> Option<Int>
1292 where
1293 Self: FloatToInt<Int>,
1294 {
1295 FloatToInt::<Int>::to_int_checked(self)
1296 }
1297
1298 /// Rounds toward zero and converts to any primitive integer type.
1299 ///
1300 /// This is equivalent to `self.to_int_checked().unwrap()`.
1301 ///
1302 /// # Panics
1303 ///
1304 /// Panics if the value is `NaN`, infinite, or does not fit in the target type.
1305 ///
1306 /// ```
1307 /// #![feature(float_conversions)]
1308 ///
1309 /// assert_eq!(255.5_f32.to_int_strict::<u8>(), 255);
1310 /// ```
1311 #[unstable(feature = "float_conversions", issue = "159913")]
1312 #[must_use = "this returns the result of the operation, \
1313 without modifying the original"]
1314 #[inline]
1315 #[track_caller]
1316 pub fn to_int_strict<Int>(self) -> Int
1317 where
1318 Self: FloatToInt<Int>,
1319 {
1320 self.to_int_checked::<Int>()
1321 .expect("the value cannot be represented in the target integer type")
1322 }
1323
1324 /// Raw transmutation to `u32`.
1325 ///
1326 /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1327 ///
1328 /// See [`from_bits`](Self::from_bits) for some discussion of the
1329 /// portability of this operation (there are almost no issues).
1330 ///
1331 /// Note that this function is distinct from `as` casting, which attempts to
1332 /// preserve the *numeric* value, and not the bitwise value.
1333 ///
1334 /// # Examples
1335 ///
1336 /// ```
1337 /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1338 /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1339 ///
1340 /// ```
1341 #[must_use = "this returns the result of the operation, \
1342 without modifying the original"]
1343 #[stable(feature = "float_bits_conv", since = "1.20.0")]
1344 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1345 #[inline]
1346 #[allow(unnecessary_transmutes)]
1347 #[ferrocene::prevalidated]
1348 pub const fn to_bits(self) -> u32 {
1349 // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1350 unsafe { mem::transmute(self) }
1351 }
1352
1353 /// Raw transmutation from `u32`.
1354 ///
1355 /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1356 /// It turns out this is incredibly portable, for two reasons:
1357 ///
1358 /// * Floats and Ints have the same endianness on all supported platforms.
1359 /// * IEEE 754 very precisely specifies the bit layout of floats.
1360 ///
1361 /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1362 /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1363 /// (notably x86 and ARM) picked the interpretation that was ultimately
1364 /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1365 /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1366 ///
1367 /// Rather than trying to preserve signaling-ness cross-platform, this
1368 /// implementation favors preserving the exact bits. This means that
1369 /// any payloads encoded in NaNs will be preserved even if the result of
1370 /// this method is sent over the network from an x86 machine to a MIPS one.
1371 ///
1372 /// If the results of this method are only manipulated by the same
1373 /// architecture that produced them, then there is no portability concern.
1374 ///
1375 /// If the input isn't NaN, then there is no portability concern.
1376 ///
1377 /// If you don't care about signalingness (very likely), then there is no
1378 /// portability concern.
1379 ///
1380 /// Note that this function is distinct from `as` casting, which attempts to
1381 /// preserve the *numeric* value, and not the bitwise value.
1382 ///
1383 /// # Examples
1384 ///
1385 /// ```
1386 /// let v = f32::from_bits(0x41480000);
1387 /// assert_eq!(v, 12.5);
1388 /// ```
1389 #[stable(feature = "float_bits_conv", since = "1.20.0")]
1390 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1391 #[must_use]
1392 #[inline]
1393 #[allow(unnecessary_transmutes)]
1394 #[ferrocene::prevalidated]
1395 pub const fn from_bits(v: u32) -> Self {
1396 // It turns out the safety issues with sNaN were overblown! Hooray!
1397 // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1398 unsafe { mem::transmute(v) }
1399 }
1400
1401 /// Returns the memory representation of this floating point number as a byte array in
1402 /// big-endian (network) byte order.
1403 ///
1404 /// See [`from_bits`](Self::from_bits) for some discussion of the
1405 /// portability of this operation (there are almost no issues).
1406 ///
1407 /// # Examples
1408 ///
1409 /// ```
1410 /// let bytes = 12.5f32.to_be_bytes();
1411 /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1412 /// ```
1413 #[must_use = "this returns the result of the operation, \
1414 without modifying the original"]
1415 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1416 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1417 #[inline]
1418 pub const fn to_be_bytes(self) -> [u8; 4] {
1419 self.to_bits().to_be_bytes()
1420 }
1421
1422 /// Returns the memory representation of this floating point number as a byte array in
1423 /// little-endian byte order.
1424 ///
1425 /// See [`from_bits`](Self::from_bits) for some discussion of the
1426 /// portability of this operation (there are almost no issues).
1427 ///
1428 /// # Examples
1429 ///
1430 /// ```
1431 /// let bytes = 12.5f32.to_le_bytes();
1432 /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1433 /// ```
1434 #[must_use = "this returns the result of the operation, \
1435 without modifying the original"]
1436 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1437 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1438 #[inline]
1439 #[ferrocene::prevalidated]
1440 pub const fn to_le_bytes(self) -> [u8; 4] {
1441 self.to_bits().to_le_bytes()
1442 }
1443
1444 /// Returns the memory representation of this floating point number as a byte array in
1445 /// native byte order.
1446 ///
1447 /// As the target platform's native endianness is used, portable code
1448 /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1449 ///
1450 /// [`to_be_bytes`]: f32::to_be_bytes
1451 /// [`to_le_bytes`]: f32::to_le_bytes
1452 ///
1453 /// See [`from_bits`](Self::from_bits) for some discussion of the
1454 /// portability of this operation (there are almost no issues).
1455 ///
1456 /// # Examples
1457 ///
1458 /// ```
1459 /// let bytes = 12.5f32.to_ne_bytes();
1460 /// assert_eq!(
1461 /// bytes,
1462 /// if cfg!(target_endian = "big") {
1463 /// [0x41, 0x48, 0x00, 0x00]
1464 /// } else {
1465 /// [0x00, 0x00, 0x48, 0x41]
1466 /// }
1467 /// );
1468 /// ```
1469 #[must_use = "this returns the result of the operation, \
1470 without modifying the original"]
1471 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1472 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1473 #[inline]
1474 pub const fn to_ne_bytes(self) -> [u8; 4] {
1475 self.to_bits().to_ne_bytes()
1476 }
1477
1478 /// Creates a floating point value from its representation as a byte array in big endian.
1479 ///
1480 /// See [`from_bits`](Self::from_bits) for some discussion of the
1481 /// portability of this operation (there are almost no issues).
1482 ///
1483 /// # Examples
1484 ///
1485 /// ```
1486 /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1487 /// assert_eq!(value, 12.5);
1488 /// ```
1489 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1490 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1491 #[must_use]
1492 #[inline]
1493 pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1494 Self::from_bits(u32::from_be_bytes(bytes))
1495 }
1496
1497 /// Creates a floating point value from its representation as a byte array in little endian.
1498 ///
1499 /// See [`from_bits`](Self::from_bits) for some discussion of the
1500 /// portability of this operation (there are almost no issues).
1501 ///
1502 /// # Examples
1503 ///
1504 /// ```
1505 /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1506 /// assert_eq!(value, 12.5);
1507 /// ```
1508 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1509 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1510 #[must_use]
1511 #[inline]
1512 #[ferrocene::prevalidated]
1513 pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1514 Self::from_bits(u32::from_le_bytes(bytes))
1515 }
1516
1517 /// Creates a floating point value from its representation as a byte array in native endian.
1518 ///
1519 /// As the target platform's native endianness is used, portable code
1520 /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1521 /// appropriate instead.
1522 ///
1523 /// [`from_be_bytes`]: f32::from_be_bytes
1524 /// [`from_le_bytes`]: f32::from_le_bytes
1525 ///
1526 /// See [`from_bits`](Self::from_bits) for some discussion of the
1527 /// portability of this operation (there are almost no issues).
1528 ///
1529 /// # Examples
1530 ///
1531 /// ```
1532 /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1533 /// [0x41, 0x48, 0x00, 0x00]
1534 /// } else {
1535 /// [0x00, 0x00, 0x48, 0x41]
1536 /// });
1537 /// assert_eq!(value, 12.5);
1538 /// ```
1539 #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1540 #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1541 #[must_use]
1542 #[inline]
1543 pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1544 Self::from_bits(u32::from_ne_bytes(bytes))
1545 }
1546
1547 /// Returns the ordering between `self` and `other`.
1548 ///
1549 /// Unlike the standard partial comparison between floating point numbers,
1550 /// this comparison always produces an ordering in accordance to
1551 /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1552 /// floating point standard. The values are ordered in the following sequence:
1553 ///
1554 /// - negative quiet NaN
1555 /// - negative signaling NaN
1556 /// - negative infinity
1557 /// - negative numbers
1558 /// - negative subnormal numbers
1559 /// - negative zero
1560 /// - positive zero
1561 /// - positive subnormal numbers
1562 /// - positive numbers
1563 /// - positive infinity
1564 /// - positive signaling NaN
1565 /// - positive quiet NaN.
1566 ///
1567 /// The ordering established by this function does not always agree with the
1568 /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1569 /// they consider negative and positive zero equal, while `total_cmp`
1570 /// doesn't.
1571 ///
1572 /// The interpretation of the signaling NaN bit follows the definition in
1573 /// the IEEE 754 standard, which may not match the interpretation by some of
1574 /// the older, non-conformant (e.g. MIPS) hardware implementations.
1575 ///
1576 /// # Example
1577 ///
1578 /// ```
1579 /// struct GoodBoy {
1580 /// name: String,
1581 /// weight: f32,
1582 /// }
1583 ///
1584 /// let mut bois = vec![
1585 /// GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1586 /// GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1587 /// GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1588 /// GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1589 /// GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1590 /// GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1591 /// ];
1592 ///
1593 /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1594 ///
1595 /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1596 /// if f32::NAN.is_sign_negative() {
1597 /// assert!(bois.into_iter().map(|b| b.weight)
1598 /// .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1599 /// .all(|(a, b)| a.to_bits() == b.to_bits()))
1600 /// } else {
1601 /// assert!(bois.into_iter().map(|b| b.weight)
1602 /// .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1603 /// .all(|(a, b)| a.to_bits() == b.to_bits()))
1604 /// }
1605 /// ```
1606 #[stable(feature = "total_cmp", since = "1.62.0")]
1607 #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1608 #[must_use]
1609 #[inline]
1610 pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1611 let mut left = self.to_bits() as i32;
1612 let mut right = other.to_bits() as i32;
1613
1614 // In case of negatives, flip all the bits except the sign
1615 // to achieve a similar layout as two's complement integers
1616 //
1617 // Why does this work? IEEE 754 floats consist of three fields:
1618 // Sign bit, exponent and mantissa. The set of exponent and mantissa
1619 // fields as a whole have the property that their bitwise order is
1620 // equal to the numeric magnitude where the magnitude is defined.
1621 // The magnitude is not normally defined on NaN values, but
1622 // IEEE 754 totalOrder defines the NaN values also to follow the
1623 // bitwise order. This leads to order explained in the doc comment.
1624 // However, the representation of magnitude is the same for negative
1625 // and positive numbers – only the sign bit is different.
1626 // To easily compare the floats as signed integers, we need to
1627 // flip the exponent and mantissa bits in case of negative numbers.
1628 // We effectively convert the numbers to "two's complement" form.
1629 //
1630 // To do the flipping, we construct a mask and XOR against it.
1631 // We branchlessly calculate an "all-ones except for the sign bit"
1632 // mask from negative-signed values: right shifting sign-extends
1633 // the integer, so we "fill" the mask with sign bits, and then
1634 // convert to unsigned to push one more zero bit.
1635 // On positive values, the mask is all zeros, so it's a no-op.
1636 left ^= (((left >> 31) as u32) >> 1) as i32;
1637 right ^= (((right >> 31) as u32) >> 1) as i32;
1638
1639 left.cmp(&right)
1640 }
1641
1642 /// Restrict a value to a certain interval unless it is NaN.
1643 ///
1644 /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1645 /// less than `min`. Otherwise this returns `self`.
1646 ///
1647 /// Note that this function returns NaN if the initial value was NaN as
1648 /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1649 /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1650 ///
1651 /// # Panics
1652 ///
1653 /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1654 ///
1655 /// # Examples
1656 ///
1657 /// ```
1658 /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1659 /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1660 /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1661 /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1662 ///
1663 /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1664 /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1665 /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1666 /// // This is definitely a negative zero.
1667 /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1668 /// ```
1669 #[must_use = "method returns a new number and does not mutate the original value"]
1670 #[stable(feature = "clamp", since = "1.50.0")]
1671 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1672 #[inline]
1673 #[expect(clippy::neg_cmp_op_on_partial_ord, reason = "Nan is also invalid")]
1674 pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1675 const_assert!(
1676 min <= max,
1677 "min > max, or either was NaN",
1678 "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1679 min: f32,
1680 max: f32,
1681 );
1682
1683 if self < min {
1684 self = min;
1685 }
1686 if self > max {
1687 self = max;
1688 }
1689 self
1690 }
1691
1692 /// Clamps this number to a symmetric range centered around zero.
1693 ///
1694 /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1695 ///
1696 /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1697 /// explicit about the intent.
1698 ///
1699 /// # Panics
1700 ///
1701 /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1702 ///
1703 /// # Examples
1704 ///
1705 /// ```
1706 /// #![feature(clamp_magnitude)]
1707 /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1708 /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1709 /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1710 /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1711 /// ```
1712 #[must_use = "this returns the clamped value and does not modify the original"]
1713 #[unstable(feature = "clamp_magnitude", issue = "148519")]
1714 #[inline]
1715 #[expect(clippy::neg_cmp_op_on_partial_ord, reason = "NaN is also invalid")]
1716 pub fn clamp_magnitude(self, limit: f32) -> f32 {
1717 assert!(limit >= 0.0, "limit must be non-negative and not NaN");
1718 let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1719 self.clamp(-limit, limit)
1720 }
1721
1722 /// Restrict a value to a certain range, unless it is NaN.
1723 ///
1724 /// This is largely equal to `max`, `min`, or `clamp`, depending on whether the range is
1725 /// `min..`, `..=max`, or `min..=max`, respectively. However, unlike `max` and `min`, it will
1726 /// panic if any bound is NaN.
1727 ///
1728 /// Note that this function returns NaN if the initial value was NaN as
1729 /// well.
1730 ///
1731 /// Exclusive ranges are not permitted.
1732 ///
1733 /// # Panics
1734 ///
1735 /// Panics on `min..=max` if `min > max`, or if any bound is NaN.
1736 ///
1737 /// # Examples
1738 ///
1739 /// ```
1740 /// #![feature(clamp_to)]
1741 /// assert_eq!((-3.0f32).clamp_to(-2.0..=1.0), -2.0);
1742 /// assert_eq!(0.0f32.clamp_to(-2.0..=1.0), 0.0);
1743 /// assert_eq!(2.0f32.clamp_to(..=1.0), 1.0);
1744 /// assert_eq!(5.0f32.clamp_to(7.0..), 7.0);
1745 /// assert!(f32::NAN.clamp_to(1.0..=2.0).is_nan());
1746 /// ```
1747 #[must_use]
1748 #[inline]
1749 #[unstable(feature = "clamp_to", issue = "147781")]
1750 pub fn clamp_to<R>(self, range: R) -> Self
1751 where
1752 R: crate::cmp::ClampBounds<Self>,
1753 {
1754 range.clamp(self)
1755 }
1756
1757 /// Computes the absolute value of `self`.
1758 ///
1759 /// This function always returns the precise result.
1760 ///
1761 /// # Examples
1762 ///
1763 /// ```
1764 /// let x = 3.5_f32;
1765 /// let y = -3.5_f32;
1766 ///
1767 /// assert_eq!(x.abs(), x);
1768 /// assert_eq!(y.abs(), -y);
1769 ///
1770 /// assert!(f32::NAN.abs().is_nan());
1771 /// ```
1772 #[must_use = "method returns a new number and does not mutate the original value"]
1773 #[stable(feature = "rust1", since = "1.0.0")]
1774 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1775 #[inline]
1776 #[ferrocene::prevalidated]
1777 pub const fn abs(self) -> f32 {
1778 intrinsics::fabs(self)
1779 }
1780
1781 /// Returns a number that represents the sign of `self`.
1782 ///
1783 /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1784 /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1785 /// - NaN if the number is NaN
1786 ///
1787 /// # Examples
1788 ///
1789 /// ```
1790 /// let f = 3.5_f32;
1791 ///
1792 /// assert_eq!(f.signum(), 1.0);
1793 /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1794 ///
1795 /// assert!(f32::NAN.signum().is_nan());
1796 /// ```
1797 #[must_use = "method returns a new number and does not mutate the original value"]
1798 #[stable(feature = "rust1", since = "1.0.0")]
1799 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1800 #[inline]
1801 #[ferrocene::prevalidated]
1802 pub const fn signum(self) -> f32 {
1803 if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1804 }
1805
1806 /// Returns a number composed of the magnitude of `self` and the sign of
1807 /// `sign`.
1808 ///
1809 /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1810 /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1811 /// returned.
1812 ///
1813 /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1814 /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1815 /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1816 /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1817 /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1818 /// info.
1819 ///
1820 /// # Examples
1821 ///
1822 /// ```
1823 /// let f = 3.5_f32;
1824 ///
1825 /// assert_eq!(f.copysign(0.42), 3.5_f32);
1826 /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1827 /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1828 /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1829 ///
1830 /// assert!(f32::NAN.copysign(1.0).is_nan());
1831 /// ```
1832 #[must_use = "method returns a new number and does not mutate the original value"]
1833 #[inline]
1834 #[stable(feature = "copysign", since = "1.35.0")]
1835 #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1836 #[ferrocene::prevalidated]
1837 pub const fn copysign(self, sign: f32) -> f32 {
1838 intrinsics::copysignf32(self, sign)
1839 }
1840
1841 /// Float addition that allows optimizations based on algebraic rules.
1842 ///
1843 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1844 #[must_use = "method returns a new number and does not mutate the original value"]
1845 #[stable(feature = "float_algebraic", since = "1.98.0")]
1846 #[rustc_const_stable(feature = "float_algebraic", since = "1.98.0")]
1847 #[inline]
1848 pub const fn algebraic_add(self, rhs: f32) -> f32 {
1849 intrinsics::fadd_algebraic(self, rhs)
1850 }
1851
1852 /// Float subtraction that allows optimizations based on algebraic rules.
1853 ///
1854 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1855 #[must_use = "method returns a new number and does not mutate the original value"]
1856 #[stable(feature = "float_algebraic", since = "1.98.0")]
1857 #[rustc_const_stable(feature = "float_algebraic", since = "1.98.0")]
1858 #[inline]
1859 pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1860 intrinsics::fsub_algebraic(self, rhs)
1861 }
1862
1863 /// Float multiplication that allows optimizations based on algebraic rules.
1864 ///
1865 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1866 #[must_use = "method returns a new number and does not mutate the original value"]
1867 #[stable(feature = "float_algebraic", since = "1.98.0")]
1868 #[rustc_const_stable(feature = "float_algebraic", since = "1.98.0")]
1869 #[inline]
1870 pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1871 intrinsics::fmul_algebraic(self, rhs)
1872 }
1873
1874 /// Float division that allows optimizations based on algebraic rules.
1875 ///
1876 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1877 #[must_use = "method returns a new number and does not mutate the original value"]
1878 #[stable(feature = "float_algebraic", since = "1.98.0")]
1879 #[rustc_const_stable(feature = "float_algebraic", since = "1.98.0")]
1880 #[inline]
1881 pub const fn algebraic_div(self, rhs: f32) -> f32 {
1882 intrinsics::fdiv_algebraic(self, rhs)
1883 }
1884
1885 /// Float remainder that allows optimizations based on algebraic rules.
1886 ///
1887 /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1888 #[must_use = "method returns a new number and does not mutate the original value"]
1889 #[stable(feature = "float_algebraic", since = "1.98.0")]
1890 #[rustc_const_stable(feature = "float_algebraic", since = "1.98.0")]
1891 #[inline]
1892 pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1893 intrinsics::frem_algebraic(self, rhs)
1894 }
1895
1896 /// Returns `self` if the value is not NaN, otherwise returns `replacement`
1897 /// if `self` is NaN.
1898 ///
1899 /// # Examples
1900 ///
1901 /// ```
1902 /// #![feature(float_nan_to)]
1903 ///
1904 /// let n = f32::NAN;
1905 /// let x = 2.0f32;
1906 /// let y = f32::INFINITY;
1907 ///
1908 /// assert_eq!(n.nan_to(0.0f32), 0.0f32);
1909 /// assert_eq!(x.nan_to(0.0f32), 2.0f32);
1910 /// assert_eq!(y.nan_to(0.0f32), f32::INFINITY);
1911 /// ```
1912 #[must_use = "method returns a new float and does not mutate the original value"]
1913 #[unstable(feature = "float_nan_to", issue = "161248")]
1914 #[rustc_const_unstable(feature = "float_nan_to", issue = "161248")]
1915 #[inline]
1916 pub const fn nan_to(self, replacement: f32) -> f32 {
1917 if self.is_nan() { replacement } else { self }
1918 }
1919}
1920
1921/// Experimental implementations of floating point functions in `core`.
1922///
1923/// _The standalone functions in this module are for testing only.
1924/// They will be stabilized as inherent methods._
1925#[unstable(feature = "core_float_math", issue = "137578")]
1926pub mod math {
1927 use crate::intrinsics;
1928 use crate::num::imp::libm;
1929
1930 /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1931 ///
1932 /// # Examples
1933 ///
1934 /// ```
1935 /// #![feature(core_float_math)]
1936 ///
1937 /// use core::f32;
1938 ///
1939 /// let f = 3.7_f32;
1940 /// let g = 3.0_f32;
1941 /// let h = -3.7_f32;
1942 ///
1943 /// assert_eq!(f32::math::floor(f), 3.0);
1944 /// assert_eq!(f32::math::floor(g), 3.0);
1945 /// assert_eq!(f32::math::floor(h), -4.0);
1946 /// ```
1947 ///
1948 /// _This standalone function is for testing only.
1949 /// It will be stabilized as an inherent method._
1950 ///
1951 /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1952 #[inline]
1953 #[unstable(feature = "core_float_math", issue = "137578")]
1954 #[must_use = "method returns a new number and does not mutate the original value"]
1955 pub const fn floor(x: f32) -> f32 {
1956 intrinsics::floorf32(x)
1957 }
1958
1959 /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1960 ///
1961 /// # Examples
1962 ///
1963 /// ```
1964 /// #![feature(core_float_math)]
1965 ///
1966 /// use core::f32;
1967 ///
1968 /// let f = 3.01_f32;
1969 /// let g = 4.0_f32;
1970 ///
1971 /// assert_eq!(f32::math::ceil(f), 4.0);
1972 /// assert_eq!(f32::math::ceil(g), 4.0);
1973 /// ```
1974 ///
1975 /// _This standalone function is for testing only.
1976 /// It will be stabilized as an inherent method._
1977 ///
1978 /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1979 #[inline]
1980 #[doc(alias = "ceiling")]
1981 #[must_use = "method returns a new number and does not mutate the original value"]
1982 #[unstable(feature = "core_float_math", issue = "137578")]
1983 pub const fn ceil(x: f32) -> f32 {
1984 intrinsics::ceilf32(x)
1985 }
1986
1987 /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1988 ///
1989 /// # Examples
1990 ///
1991 /// ```
1992 /// #![feature(core_float_math)]
1993 ///
1994 /// use core::f32;
1995 ///
1996 /// let f = 3.3_f32;
1997 /// let g = -3.3_f32;
1998 /// let h = -3.7_f32;
1999 /// let i = 3.5_f32;
2000 /// let j = 4.5_f32;
2001 ///
2002 /// assert_eq!(f32::math::round(f), 3.0);
2003 /// assert_eq!(f32::math::round(g), -3.0);
2004 /// assert_eq!(f32::math::round(h), -4.0);
2005 /// assert_eq!(f32::math::round(i), 4.0);
2006 /// assert_eq!(f32::math::round(j), 5.0);
2007 /// ```
2008 ///
2009 /// _This standalone function is for testing only.
2010 /// It will be stabilized as an inherent method._
2011 ///
2012 /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
2013 #[inline]
2014 #[unstable(feature = "core_float_math", issue = "137578")]
2015 #[must_use = "method returns a new number and does not mutate the original value"]
2016 pub const fn round(x: f32) -> f32 {
2017 intrinsics::roundf32(x)
2018 }
2019
2020 /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
2021 /// details.
2022 ///
2023 /// # Examples
2024 ///
2025 /// ```
2026 /// #![feature(core_float_math)]
2027 ///
2028 /// use core::f32;
2029 ///
2030 /// let f = 3.3_f32;
2031 /// let g = -3.3_f32;
2032 /// let h = 3.5_f32;
2033 /// let i = 4.5_f32;
2034 ///
2035 /// assert_eq!(f32::math::round_ties_even(f), 3.0);
2036 /// assert_eq!(f32::math::round_ties_even(g), -3.0);
2037 /// assert_eq!(f32::math::round_ties_even(h), 4.0);
2038 /// assert_eq!(f32::math::round_ties_even(i), 4.0);
2039 /// ```
2040 ///
2041 /// _This standalone function is for testing only.
2042 /// It will be stabilized as an inherent method._
2043 ///
2044 /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
2045 #[inline]
2046 #[unstable(feature = "core_float_math", issue = "137578")]
2047 #[must_use = "method returns a new number and does not mutate the original value"]
2048 pub const fn round_ties_even(x: f32) -> f32 {
2049 intrinsics::round_ties_even_f32(x)
2050 }
2051
2052 /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
2053 ///
2054 /// # Examples
2055 ///
2056 /// ```
2057 /// #![feature(core_float_math)]
2058 ///
2059 /// use core::f32;
2060 ///
2061 /// let f = 3.7_f32;
2062 /// let g = 3.0_f32;
2063 /// let h = -3.7_f32;
2064 ///
2065 /// assert_eq!(f32::math::trunc(f), 3.0);
2066 /// assert_eq!(f32::math::trunc(g), 3.0);
2067 /// assert_eq!(f32::math::trunc(h), -3.0);
2068 /// ```
2069 ///
2070 /// _This standalone function is for testing only.
2071 /// It will be stabilized as an inherent method._
2072 ///
2073 /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
2074 #[inline]
2075 #[doc(alias = "truncate")]
2076 #[must_use = "method returns a new number and does not mutate the original value"]
2077 #[unstable(feature = "core_float_math", issue = "137578")]
2078 pub const fn trunc(x: f32) -> f32 {
2079 intrinsics::truncf32(x)
2080 }
2081
2082 /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
2083 ///
2084 /// # Examples
2085 ///
2086 /// ```
2087 /// #![feature(core_float_math)]
2088 ///
2089 /// use core::f32;
2090 ///
2091 /// let x = 3.6_f32;
2092 /// let y = -3.6_f32;
2093 /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
2094 /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
2095 ///
2096 /// assert!(abs_difference_x <= f32::EPSILON);
2097 /// assert!(abs_difference_y <= f32::EPSILON);
2098 /// ```
2099 ///
2100 /// _This standalone function is for testing only.
2101 /// It will be stabilized as an inherent method._
2102 ///
2103 /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
2104 #[inline]
2105 #[unstable(feature = "core_float_math", issue = "137578")]
2106 #[must_use = "method returns a new number and does not mutate the original value"]
2107 pub const fn fract(x: f32) -> f32 {
2108 x - trunc(x)
2109 }
2110
2111 /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
2112 ///
2113 /// # Examples
2114 ///
2115 /// ```
2116 /// # #![allow(unused_features)]
2117 /// #![feature(core_float_math)]
2118 ///
2119 /// # // FIXME(#140515): mingw has an incorrect fma
2120 /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
2121 /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
2122 /// use core::f32;
2123 ///
2124 /// let m = 10.0_f32;
2125 /// let x = 4.0_f32;
2126 /// let b = 60.0_f32;
2127 ///
2128 /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
2129 /// assert_eq!(m * x + b, 100.0);
2130 ///
2131 /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
2132 /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
2133 /// let minus_one = -1.0_f32;
2134 ///
2135 /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
2136 /// assert_eq!(
2137 /// f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
2138 /// -f32::EPSILON * f32::EPSILON
2139 /// );
2140 /// // Different rounding with the non-fused multiply and add.
2141 /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
2142 /// # }
2143 /// ```
2144 ///
2145 /// _This standalone function is for testing only.
2146 /// It will be stabilized as an inherent method._
2147 ///
2148 /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
2149 #[inline]
2150 #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
2151 #[must_use = "method returns a new number and does not mutate the original value"]
2152 #[unstable(feature = "core_float_math", issue = "137578")]
2153 pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
2154 intrinsics::fmaf32(x, y, z)
2155 }
2156
2157 /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
2158 ///
2159 /// # Examples
2160 ///
2161 /// ```
2162 /// #![feature(core_float_math)]
2163 ///
2164 /// use core::f32;
2165 ///
2166 /// let a: f32 = 7.0;
2167 /// let b = 4.0;
2168 /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
2169 /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
2170 /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
2171 /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
2172 /// ```
2173 ///
2174 /// _This standalone function is for testing only.
2175 /// It will be stabilized as an inherent method._
2176 ///
2177 /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
2178 #[inline]
2179 #[unstable(feature = "core_float_math", issue = "137578")]
2180 #[must_use = "method returns a new number and does not mutate the original value"]
2181 pub fn div_euclid(x: f32, rhs: f32) -> f32 {
2182 let q = trunc(x / rhs);
2183 if x % rhs < 0.0 {
2184 return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
2185 }
2186 q
2187 }
2188
2189 /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
2190 ///
2191 /// # Examples
2192 ///
2193 /// ```
2194 /// #![feature(core_float_math)]
2195 ///
2196 /// use core::f32;
2197 ///
2198 /// let a: f32 = 7.0;
2199 /// let b = 4.0;
2200 /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
2201 /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
2202 /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
2203 /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
2204 /// // limitation due to round-off error
2205 /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
2206 /// ```
2207 ///
2208 /// _This standalone function is for testing only.
2209 /// It will be stabilized as an inherent method._
2210 ///
2211 /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
2212 #[inline]
2213 #[doc(alias = "modulo", alias = "mod")]
2214 #[unstable(feature = "core_float_math", issue = "137578")]
2215 #[must_use = "method returns a new number and does not mutate the original value"]
2216 pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
2217 let r = x % rhs;
2218 if r < 0.0 { r + rhs.abs() } else { r }
2219 }
2220
2221 /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
2222 ///
2223 /// # Examples
2224 ///
2225 /// ```
2226 /// #![feature(core_float_math)]
2227 ///
2228 /// use core::f32;
2229 ///
2230 /// let x = 2.0_f32;
2231 /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
2232 /// assert!(abs_difference <= 1e-5);
2233 ///
2234 /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
2235 /// ```
2236 ///
2237 /// _This standalone function is for testing only.
2238 /// It will be stabilized as an inherent method._
2239 ///
2240 /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
2241 #[inline]
2242 #[must_use = "method returns a new number and does not mutate the original value"]
2243 #[unstable(feature = "core_float_math", issue = "137578")]
2244 pub fn powi(x: f32, n: i32) -> f32 {
2245 intrinsics::powif32(x, n)
2246 }
2247
2248 /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
2249 ///
2250 /// # Examples
2251 ///
2252 /// ```
2253 /// #![feature(core_float_math)]
2254 ///
2255 /// use core::f32;
2256 ///
2257 /// let positive = 4.0_f32;
2258 /// let negative = -4.0_f32;
2259 /// let negative_zero = -0.0_f32;
2260 ///
2261 /// assert_eq!(f32::math::sqrt(positive), 2.0);
2262 /// assert!(f32::math::sqrt(negative).is_nan());
2263 /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
2264 /// ```
2265 ///
2266 /// _This standalone function is for testing only.
2267 /// It will be stabilized as an inherent method._
2268 ///
2269 /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
2270 #[inline]
2271 #[doc(alias = "squareRoot")]
2272 #[unstable(feature = "core_float_math", issue = "137578")]
2273 #[must_use = "method returns a new number and does not mutate the original value"]
2274 pub fn sqrt(x: f32) -> f32 {
2275 intrinsics::sqrtf32(x)
2276 }
2277
2278 /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
2279 ///
2280 /// # Examples
2281 ///
2282 /// ```
2283 /// #![feature(core_float_math)]
2284 ///
2285 /// use core::f32;
2286 ///
2287 /// let x = 3.0f32;
2288 /// let y = -3.0f32;
2289 ///
2290 /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
2291 /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
2292 ///
2293 /// assert!(abs_difference_x <= 1e-6);
2294 /// assert!(abs_difference_y <= 1e-6);
2295 /// ```
2296 ///
2297 /// _This standalone function is for testing only.
2298 /// It will be stabilized as an inherent method._
2299 ///
2300 /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
2301 #[inline]
2302 #[stable(feature = "rust1", since = "1.0.0")]
2303 #[deprecated(
2304 since = "1.10.0",
2305 note = "you probably meant `(self - other).abs()`: \
2306 this operation is `(self - other).max(0.0)` \
2307 except that `abs_sub` also propagates NaNs (also \
2308 known as `fdimf` in C). If you truly need the positive \
2309 difference, consider using that expression or the C function \
2310 `fdimf`, depending on how you wish to handle NaN (please consider \
2311 filing an issue describing your use-case too)."
2312 )]
2313 #[must_use = "method returns a new number and does not mutate the original value"]
2314 pub fn abs_sub(x: f32, other: f32) -> f32 {
2315 libm::fdimf(x, other)
2316 }
2317
2318 /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2319 ///
2320 /// # Unspecified precision
2321 ///
2322 /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2323 /// can even differ within the same execution from one invocation to the next.
2324 /// This function currently corresponds to the `cbrtf` from libc on Unix
2325 /// and Windows. Note that this might change in the future.
2326 ///
2327 /// # Examples
2328 ///
2329 /// ```
2330 /// #![feature(core_float_math)]
2331 ///
2332 /// use core::f32;
2333 ///
2334 /// let x = 8.0f32;
2335 ///
2336 /// // x^(1/3) - 2 == 0
2337 /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2338 ///
2339 /// assert!(abs_difference <= 1e-6);
2340 /// ```
2341 ///
2342 /// _This standalone function is for testing only.
2343 /// It will be stabilized as an inherent method._
2344 ///
2345 /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2346 #[inline]
2347 #[must_use = "method returns a new number and does not mutate the original value"]
2348 #[unstable(feature = "core_float_math", issue = "137578")]
2349 pub fn cbrt(x: f32) -> f32 {
2350 libm::cbrtf(x)
2351 }
2352}