Struct Float64

Source

#[repr(C, align(8))]
pub struct Float64(pub f64);

Expand description

A wire-encoded f64

Tuple Fields§

§0: f64

Methods from Deref<Target = f64>§

1.0.0 · Source

pub fn floor(self) -> f64

Returns the largest integer that is less than or equal to self.

This function always returns the precise result.

§Examples

let f = 3.7_f64;
let g = 3.0_f64;
let h = -3.7_f64;

assert_eq!(f.floor(), 3.0);
assert_eq!(g.floor(), 3.0);
assert_eq!(h.floor(), -4.0);

1.0.0 · Source

pub fn ceil(self) -> f64

Returns the smallest integer that is greater than or equal to self.

This function always returns the precise result.

§Examples

let f = 3.01_f64;
let g = 4.0_f64;
let h = -3.01_f64;

assert_eq!(f.ceil(), 4.0);
assert_eq!(g.ceil(), 4.0);
assert_eq!(h.ceil(), -3.0);

1.0.0 · Source

pub fn round(self) -> f64

Returns the nearest integer to self. If a value is half-way between two integers, round away from 0.0.

This function always returns the precise result.

On most hardware platforms, round_ties_even may execute faster than round. If both rounding methods fit the use case, consider using round_ties_even. Note that the two methods apply different rounding rules to values exactly halfway between two integers.

§Examples

let f = 3.3_f64;
let g = -3.3_f64;
let h = -3.7_f64;
let i = 3.5_f64;
let j = 4.5_f64;

assert_eq!(f.round(), 3.0);
assert_eq!(g.round(), -3.0);
assert_eq!(h.round(), -4.0);
assert_eq!(i.round(), 4.0);
assert_eq!(j.round(), 5.0);

1.77.0 · Source

pub fn round_ties_even(self) -> f64

Returns the nearest integer to a number. Rounds half-way cases to the number with an even least significant digit.

This function always returns the precise result.

§Examples

let f = 3.3_f64;
let g = -3.3_f64;
let h = 3.5_f64;
let i = 4.5_f64;

assert_eq!(f.round_ties_even(), 3.0);
assert_eq!(g.round_ties_even(), -3.0);
assert_eq!(h.round_ties_even(), 4.0);
assert_eq!(i.round_ties_even(), 4.0);

1.0.0 · Source

pub fn trunc(self) -> f64

Returns the integer part of self. This means that non-integer numbers are always truncated towards zero.

This function always returns the precise result.

§Examples

let f = 3.7_f64;
let g = 3.0_f64;
let h = -3.7_f64;

assert_eq!(f.trunc(), 3.0);
assert_eq!(g.trunc(), 3.0);
assert_eq!(h.trunc(), -3.0);

1.0.0 · Source

pub fn fract(self) -> f64

Returns the fractional part of self.

This function always returns the precise result.

§Examples

let x = 3.6_f64;
let y = -3.6_f64;
let abs_difference_x = (x.fract() - 0.6).abs();
let abs_difference_y = (y.fract() - (-0.6)).abs();

assert!(abs_difference_x < 1e-10);
assert!(abs_difference_y < 1e-10);

1.0.0 · Source

pub fn mul_add(self, a: f64, b: f64) -> f64

Fused multiply-add. Computes (self * a) + b with only one rounding error, yielding a more accurate result than an unfused multiply-add.

Using mul_add may be more performant than an unfused multiply-add if the target architecture has a dedicated fma CPU instruction. However, this is not always true, and will be heavily dependant on designing algorithms with specific target hardware in mind.

§Precision

The result of this operation is guaranteed to be the rounded infinite-precision result. It is specified by IEEE 754 as fusedMultiplyAdd and guaranteed not to change.

§Examples

let m = 10.0_f64;
let x = 4.0_f64;
let b = 60.0_f64;

assert_eq!(m.mul_add(x, b), 100.0);
assert_eq!(m * x + b, 100.0);

let one_plus_eps = 1.0_f64 + f64::EPSILON;
let one_minus_eps = 1.0_f64 - f64::EPSILON;
let minus_one = -1.0_f64;

// The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
assert_eq!(one_plus_eps.mul_add(one_minus_eps, minus_one), -f64::EPSILON * f64::EPSILON);
// Different rounding with the non-fused multiply and add.
assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);

1.38.0 · Source

pub fn div_euclid(self, rhs: f64) -> f64

Calculates Euclidean division, the matching method for rem_euclid.

This computes the integer n such that self = n * rhs + self.rem_euclid(rhs). In other words, the result is self / rhs rounded to the integer n such that self >= n * rhs.

§Precision

The result of this operation is guaranteed to be the rounded infinite-precision result.

§Examples

let a: f64 = 7.0;
let b = 4.0;
assert_eq!(a.div_euclid(b), 1.0); // 7.0 > 4.0 * 1.0
assert_eq!((-a).div_euclid(b), -2.0); // -7.0 >= 4.0 * -2.0
assert_eq!(a.div_euclid(-b), -1.0); // 7.0 >= -4.0 * -1.0
assert_eq!((-a).div_euclid(-b), 2.0); // -7.0 >= -4.0 * 2.0

1.38.0 · Source

pub fn rem_euclid(self, rhs: f64) -> f64

Calculates the least nonnegative remainder of self when divided by rhs.

In particular, the return value r satisfies 0.0 <= r < rhs.abs() in most cases. However, due to a floating point round-off error it can result in r == rhs.abs(), violating the mathematical definition, if self is much smaller than rhs.abs() in magnitude and self < 0.0. This result is not an element of the function’s codomain, but it is the closest floating point number in the real numbers and thus fulfills the property self == self.div_euclid(rhs) * rhs + self.rem_euclid(rhs) approximately.

§Precision

The result of this operation is guaranteed to be the rounded infinite-precision result.

§Examples

let a: f64 = 7.0;
let b = 4.0;
assert_eq!(a.rem_euclid(b), 3.0);
assert_eq!((-a).rem_euclid(b), 1.0);
assert_eq!(a.rem_euclid(-b), 3.0);
assert_eq!((-a).rem_euclid(-b), 1.0);
// limitation due to round-off error
assert!((-f64::EPSILON).rem_euclid(3.0) != 0.0);

1.0.0 · Source

pub fn powi(self, n: i32) -> f64

Raises a number to an integer power.

Using this function is generally faster than using powf. It might have a different sequence of rounding operations than powf, so the results are not guaranteed to agree.

Note that this function is special in that it can return non-NaN results for NaN inputs. For example, f64::powi(f64::NAN, 0) returns 1.0. However, if an input is a signaling NaN, then the result is non-deterministically either a NaN or the result that the corresponding quiet NaN would produce.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let x = 2.0_f64;
let abs_difference = (x.powi(2) - (x * x)).abs();
assert!(abs_difference <= 1e-14);

assert_eq!(f64::powi(f64::NAN, 0), 1.0);
assert_eq!(f64::powi(0.0, 0), 1.0);

1.0.0 · Source

pub fn powf(self, n: f64) -> f64

Raises a number to a floating point power.

Note that this function is special in that it can return non-NaN results for NaN inputs. For example, f64::powf(f64::NAN, 0.0) returns 1.0. However, if an input is a signaling NaN, then the result is non-deterministically either a NaN or the result that the corresponding quiet NaN would produce.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let x = 2.0_f64;
let abs_difference = (x.powf(2.0) - (x * x)).abs();
assert!(abs_difference <= 1e-14);

assert_eq!(f64::powf(1.0, f64::NAN), 1.0);
assert_eq!(f64::powf(f64::NAN, 0.0), 1.0);
assert_eq!(f64::powf(0.0, 0.0), 1.0);

1.0.0 · Source

pub fn sqrt(self) -> f64

Returns the square root of a number.

Returns NaN if self is a negative number other than -0.0.

§Precision

The result of this operation is guaranteed to be the rounded infinite-precision result. It is specified by IEEE 754 as squareRoot and guaranteed not to change.

§Examples

let positive = 4.0_f64;
let negative = -4.0_f64;
let negative_zero = -0.0_f64;

assert_eq!(positive.sqrt(), 2.0);
assert!(negative.sqrt().is_nan());
assert!(negative_zero.sqrt() == negative_zero);

1.0.0 · Source

pub fn exp(self) -> f64

Returns e^(self), (the exponential function).

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let one = 1.0_f64;
// e^1
let e = one.exp();

// ln(e) - 1 == 0
let abs_difference = (e.ln() - 1.0).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn exp2(self) -> f64

Returns 2^(self).

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let f = 2.0_f64;

// 2^2 - 4 == 0
let abs_difference = (f.exp2() - 4.0).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn ln(self) -> f64

Returns the natural logarithm of the number.

This returns NaN when the number is negative, and negative infinity when number is zero.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let one = 1.0_f64;
// e^1
let e = one.exp();

// ln(e) - 1 == 0
let abs_difference = (e.ln() - 1.0).abs();

assert!(abs_difference < 1e-10);

Non-positive values:

assert_eq!(0_f64.ln(), f64::NEG_INFINITY);
assert!((-42_f64).ln().is_nan());

1.0.0 · Source

pub fn log(self, base: f64) -> f64

Returns the logarithm of the number with respect to an arbitrary base.

This returns NaN when the number is negative, and negative infinity when number is zero.

The result might not be correctly rounded owing to implementation details; self.log2() can produce more accurate results for base 2, and self.log10() can produce more accurate results for base 10.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let twenty_five = 25.0_f64;

// log5(25) - 2 == 0
let abs_difference = (twenty_five.log(5.0) - 2.0).abs();

assert!(abs_difference < 1e-10);

Non-positive values:

assert_eq!(0_f64.log(10.0), f64::NEG_INFINITY);
assert!((-42_f64).log(10.0).is_nan());

1.0.0 · Source

pub fn log2(self) -> f64

Returns the base 2 logarithm of the number.

This returns NaN when the number is negative, and negative infinity when number is zero.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let four = 4.0_f64;

// log2(4) - 2 == 0
let abs_difference = (four.log2() - 2.0).abs();

assert!(abs_difference < 1e-10);

Non-positive values:

assert_eq!(0_f64.log2(), f64::NEG_INFINITY);
assert!((-42_f64).log2().is_nan());

1.0.0 · Source

pub fn log10(self) -> f64

Returns the base 10 logarithm of the number.

This returns NaN when the number is negative, and negative infinity when number is zero.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let hundred = 100.0_f64;

// log10(100) - 2 == 0
let abs_difference = (hundred.log10() - 2.0).abs();

assert!(abs_difference < 1e-10);

Non-positive values:

assert_eq!(0_f64.log10(), f64::NEG_INFINITY);
assert!((-42_f64).log10().is_nan());

1.0.0 · Source

pub fn abs_sub(self, other: f64) -> f64

👎Deprecated since 1.10.0:

you probably meant (self - other).abs(): this operation is (self - other).max(0.0) except that abs_sub also propagates NaNs (also known as fdim in C). If you truly need the positive difference, consider using that expression or the C function fdim, depending on how you wish to handle NaN (please consider filing an issue describing your use-case too).

The positive difference of two numbers.

If self <= other: 0.0
Else: self - other

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the fdim from libc on Unix and Windows. Note that this might change in the future.

§Examples

let x = 3.0_f64;
let y = -3.0_f64;

let abs_difference_x = (x.abs_sub(1.0) - 2.0).abs();
let abs_difference_y = (y.abs_sub(1.0) - 0.0).abs();

assert!(abs_difference_x < 1e-10);
assert!(abs_difference_y < 1e-10);

1.0.0 · Source

pub fn cbrt(self) -> f64

Returns the cube root of a number.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the cbrt from libc on Unix and Windows. Note that this might change in the future.

§Examples

let x = 8.0_f64;

// x^(1/3) - 2 == 0
let abs_difference = (x.cbrt() - 2.0).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn hypot(self, other: f64) -> f64

Compute the distance between the origin and a point (x, y) on the Euclidean plane. Equivalently, compute the length of the hypotenuse of a right-angle triangle with other sides having length x.abs() and y.abs().

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the hypot from libc on Unix and Windows. Note that this might change in the future.

§Examples

let x = 2.0_f64;
let y = 3.0_f64;

// sqrt(x^2 + y^2)
let abs_difference = (x.hypot(y) - (x.powi(2) + y.powi(2)).sqrt()).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn sin(self) -> f64

Computes the sine of a number (in radians).

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let x = std::f64::consts::FRAC_PI_2;

let abs_difference = (x.sin() - 1.0).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn cos(self) -> f64

Computes the cosine of a number (in radians).

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let x = 2.0 * std::f64::consts::PI;

let abs_difference = (x.cos() - 1.0).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn tan(self) -> f64

Computes the tangent of a number (in radians).

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the tan from libc on Unix and Windows. Note that this might change in the future.

§Examples

let x = std::f64::consts::FRAC_PI_4;
let abs_difference = (x.tan() - 1.0).abs();

assert!(abs_difference < 1e-14);

1.0.0 · Source

pub fn asin(self) -> f64

Computes the arcsine of a number. Return value is in radians in the range [-pi/2, pi/2] or NaN if the number is outside the range [-1, 1].

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the asin from libc on Unix and Windows. Note that this might change in the future.

§Examples

let f = std::f64::consts::FRAC_PI_4;

// asin(sin(pi/2))
let abs_difference = (f.sin().asin() - f).abs();

assert!(abs_difference < 1e-14);

1.0.0 · Source

pub fn acos(self) -> f64

Computes the arccosine of a number. Return value is in radians in the range [0, pi] or NaN if the number is outside the range [-1, 1].

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the acos from libc on Unix and Windows. Note that this might change in the future.

§Examples

let f = std::f64::consts::FRAC_PI_4;

// acos(cos(pi/4))
let abs_difference = (f.cos().acos() - std::f64::consts::FRAC_PI_4).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn atan(self) -> f64

Computes the arctangent of a number. Return value is in radians in the range [-pi/2, pi/2];

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the atan from libc on Unix and Windows. Note that this might change in the future.

§Examples

let f = 1.0_f64;

// atan(tan(1))
let abs_difference = (f.tan().atan() - 1.0).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn atan2(self, other: f64) -> f64

Computes the four quadrant arctangent of self (y) and other (x) in radians.

`x`	`y`	Piecewise Definition	Range
`>= +0`	`>= +0`	`arctan(y/x)`	`[+0, +pi/2]`
`>= +0`	`<= -0`	`arctan(y/x)`	`[-pi/2, -0]`
`<= -0`	`>= +0`	`arctan(y/x) + pi`	`[+pi/2, +pi]`
`<= -0`	`<= -0`	`arctan(y/x) - pi`	`[-pi, -pi/2]`

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the atan2 from libc on Unix and Windows. Note that this might change in the future.

§Examples

// Positive angles measured counter-clockwise
// from positive x axis
// -pi/4 radians (45 deg clockwise)
let x1 = 3.0_f64;
let y1 = -3.0_f64;

// 3pi/4 radians (135 deg counter-clockwise)
let x2 = -3.0_f64;
let y2 = 3.0_f64;

let abs_difference_1 = (y1.atan2(x1) - (-std::f64::consts::FRAC_PI_4)).abs();
let abs_difference_2 = (y2.atan2(x2) - (3.0 * std::f64::consts::FRAC_PI_4)).abs();

assert!(abs_difference_1 < 1e-10);
assert!(abs_difference_2 < 1e-10);

1.0.0 · Source

pub fn sin_cos(self) -> (f64, f64)

Simultaneously computes the sine and cosine of the number, x. Returns (sin(x), cos(x)).

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the (f64::sin(x), f64::cos(x)). Note that this might change in the future.

§Examples

let x = std::f64::consts::FRAC_PI_4;
let f = x.sin_cos();

let abs_difference_0 = (f.0 - x.sin()).abs();
let abs_difference_1 = (f.1 - x.cos()).abs();

assert!(abs_difference_0 < 1e-10);
assert!(abs_difference_1 < 1e-10);

1.0.0 · Source

pub fn exp_m1(self) -> f64

Returns e^(self) - 1 in a way that is accurate even if the number is close to zero.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the expm1 from libc on Unix and Windows. Note that this might change in the future.

§Examples

let x = 1e-16_f64;

// for very small x, e^x is approximately 1 + x + x^2 / 2
let approx = x + x * x / 2.0;
let abs_difference = (x.exp_m1() - approx).abs();

assert!(abs_difference < 1e-20);

1.0.0 · Source

pub fn ln_1p(self) -> f64

Returns ln(1+n) (natural logarithm) more accurately than if the operations were performed separately.

This returns NaN when n < -1.0, and negative infinity when n == -1.0.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the log1p from libc on Unix and Windows. Note that this might change in the future.

§Examples

let x = 1e-16_f64;

// for very small x, ln(1 + x) is approximately x - x^2 / 2
let approx = x - x * x / 2.0;
let abs_difference = (x.ln_1p() - approx).abs();

assert!(abs_difference < 1e-20);

Out-of-range values:

assert_eq!((-1.0_f64).ln_1p(), f64::NEG_INFINITY);
assert!((-2.0_f64).ln_1p().is_nan());

1.0.0 · Source

pub fn sinh(self) -> f64

Hyperbolic sine function.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the sinh from libc on Unix and Windows. Note that this might change in the future.

§Examples

let e = std::f64::consts::E;
let x = 1.0_f64;

let f = x.sinh();
// Solving sinh() at 1 gives `(e^2-1)/(2e)`
let g = ((e * e) - 1.0) / (2.0 * e);
let abs_difference = (f - g).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn cosh(self) -> f64

Hyperbolic cosine function.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the cosh from libc on Unix and Windows. Note that this might change in the future.

§Examples

let e = std::f64::consts::E;
let x = 1.0_f64;
let f = x.cosh();
// Solving cosh() at 1 gives this result
let g = ((e * e) + 1.0) / (2.0 * e);
let abs_difference = (f - g).abs();

// Same result
assert!(abs_difference < 1.0e-10);

1.0.0 · Source

pub fn tanh(self) -> f64

Hyperbolic tangent function.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the tanh from libc on Unix and Windows. Note that this might change in the future.

§Examples

let e = std::f64::consts::E;
let x = 1.0_f64;

let f = x.tanh();
// Solving tanh() at 1 gives `(1 - e^(-2))/(1 + e^(-2))`
let g = (1.0 - e.powi(-2)) / (1.0 + e.powi(-2));
let abs_difference = (f - g).abs();

assert!(abs_difference < 1.0e-10);

1.0.0 · Source

pub fn asinh(self) -> f64

Inverse hyperbolic sine function.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let x = 1.0_f64;
let f = x.sinh().asinh();

let abs_difference = (f - x).abs();

assert!(abs_difference < 1.0e-10);

1.0.0 · Source

pub fn acosh(self) -> f64

Inverse hyperbolic cosine function.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let x = 1.0_f64;
let f = x.cosh().acosh();

let abs_difference = (f - x).abs();

assert!(abs_difference < 1.0e-10);

1.0.0 · Source

pub fn atanh(self) -> f64

Inverse hyperbolic tangent function.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let x = std::f64::consts::FRAC_PI_6;
let f = x.tanh().atanh();

let abs_difference = (f - x).abs();

assert!(abs_difference < 1.0e-10);

Source

pub fn gamma(self) -> f64

🔬This is a nightly-only experimental API. (float_gamma)

Gamma function.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the tgamma from libc on Unix and Windows. Note that this might change in the future.

§Examples

#![feature(float_gamma)]
let x = 5.0f64;

let abs_difference = (x.gamma() - 24.0).abs();

assert!(abs_difference <= 1e-10);

Source

pub fn ln_gamma(self) -> (f64, i32)

🔬This is a nightly-only experimental API. (float_gamma)

Natural logarithm of the absolute value of the gamma function

The integer part of the tuple indicates the sign of the gamma function.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next. This function currently corresponds to the lgamma_r from libc on Unix and Windows. Note that this might change in the future.

§Examples

#![feature(float_gamma)]
let x = 2.0f64;

let abs_difference = (x.ln_gamma().0 - 0.0).abs();

assert!(abs_difference <= f64::EPSILON);

Source

pub fn erf(self) -> f64

🔬This is a nightly-only experimental API. (float_erf)

Error function.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

This function currently corresponds to the erf from libc on Unix and Windows. Note that this might change in the future.

§Examples

#![feature(float_erf)]
/// The error function relates what percent of a normal distribution lies
/// within `x` standard deviations (scaled by `1/sqrt(2)`).
fn within_standard_deviations(x: f64) -> f64 {
    (x * std::f64::consts::FRAC_1_SQRT_2).erf() * 100.0
}

// 68% of a normal distribution is within one standard deviation
assert!((within_standard_deviations(1.0) - 68.269).abs() < 0.01);
// 95% of a normal distribution is within two standard deviations
assert!((within_standard_deviations(2.0) - 95.450).abs() < 0.01);
// 99.7% of a normal distribution is within three standard deviations
assert!((within_standard_deviations(3.0) - 99.730).abs() < 0.01);

Source

pub fn erfc(self) -> f64

🔬This is a nightly-only experimental API. (float_erf)

Complementary error function.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

This function currently corresponds to the erfc from libc on Unix and Windows. Note that this might change in the future.

§Examples

#![feature(float_erf)]
let x: f64 = 0.123;

let one = x.erf() + x.erfc();
let abs_difference = (one - 1.0).abs();

assert!(abs_difference <= 1e-10);

1.0.0 · Source

pub fn is_nan(self) -> bool

Returns true if this value is NaN.

let nan = f64::NAN;
let f = 7.0_f64;

assert!(nan.is_nan());
assert!(!f.is_nan());

1.0.0 · Source

pub fn is_infinite(self) -> bool

Returns true if this value is positive infinity or negative infinity, and false otherwise.

let f = 7.0f64;
let inf = f64::INFINITY;
let neg_inf = f64::NEG_INFINITY;
let nan = f64::NAN;

assert!(!f.is_infinite());
assert!(!nan.is_infinite());

assert!(inf.is_infinite());
assert!(neg_inf.is_infinite());

1.0.0 · Source

pub fn is_finite(self) -> bool

Returns true if this number is neither infinite nor NaN.

let f = 7.0f64;
let inf: f64 = f64::INFINITY;
let neg_inf: f64 = f64::NEG_INFINITY;
let nan: f64 = f64::NAN;

assert!(f.is_finite());

assert!(!nan.is_finite());
assert!(!inf.is_finite());
assert!(!neg_inf.is_finite());

1.53.0 · Source

pub fn is_subnormal(self) -> bool

Returns true if the number is subnormal.

let min = f64::MIN_POSITIVE; // 2.2250738585072014e-308_f64
let max = f64::MAX;
let lower_than_min = 1.0e-308_f64;
let zero = 0.0_f64;

assert!(!min.is_subnormal());
assert!(!max.is_subnormal());

assert!(!zero.is_subnormal());
assert!(!f64::NAN.is_subnormal());
assert!(!f64::INFINITY.is_subnormal());
// Values between `0` and `min` are Subnormal.
assert!(lower_than_min.is_subnormal());

1.0.0 · Source

pub fn is_normal(self) -> bool

Returns true if the number is neither zero, infinite, subnormal, or NaN.

let min = f64::MIN_POSITIVE; // 2.2250738585072014e-308f64
let max = f64::MAX;
let lower_than_min = 1.0e-308_f64;
let zero = 0.0f64;

assert!(min.is_normal());
assert!(max.is_normal());

assert!(!zero.is_normal());
assert!(!f64::NAN.is_normal());
assert!(!f64::INFINITY.is_normal());
// Values between `0` and `min` are Subnormal.
assert!(!lower_than_min.is_normal());

1.0.0 · Source

pub fn classify(self) -> FpCategory

Returns the floating point category of the number. If only one property is going to be tested, it is generally faster to use the specific predicate instead.

use std::num::FpCategory;

let num = 12.4_f64;
let inf = f64::INFINITY;

assert_eq!(num.classify(), FpCategory::Normal);
assert_eq!(inf.classify(), FpCategory::Infinite);

1.0.0 · Source

pub fn is_sign_positive(self) -> bool

Returns true if self has a positive sign, including +0.0, NaNs with positive sign bit and positive infinity.

Note that IEEE 754 doesn’t assign any meaning to the sign bit in case of a NaN, and as Rust doesn’t guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the result of is_sign_positive on a NaN might produce an unexpected or non-portable result. See the specification of NaN bit patterns for more info. Use self.signum() == 1.0 if you need fully portable behavior (evaluates to false for all NaNs).

let f = 7.0_f64;
let g = -7.0_f64;

assert!(f.is_sign_positive());
assert!(!g.is_sign_positive());

1.0.0 · Source

pub fn is_sign_negative(self) -> bool

Returns true if self has a negative sign, including -0.0, NaNs with negative sign bit and negative infinity.

Note that IEEE 754 doesn’t assign any meaning to the sign bit in case of a NaN, and as Rust doesn’t guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the result of is_sign_negative on a NaN might produce an unexpected or non-portable result. See the specification of NaN bit patterns for more info. Use self.signum() == -1.0 if you need fully portable behavior (evaluates to false for all NaNs).

let f = 7.0_f64;
let g = -7.0_f64;

assert!(!f.is_sign_negative());
assert!(g.is_sign_negative());

1.86.0 · Source

pub fn next_up(self) -> f64

Returns the least number greater than self.

Let TINY be the smallest representable positive f64. Then,

if self.is_nan(), this returns self;
if self is NEG_INFINITY, this returns MIN;
if self is -TINY, this returns -0.0;
if self is -0.0 or +0.0, this returns TINY;
if self is MAX or INFINITY, this returns INFINITY;
otherwise the unique least value greater than self is returned.

The identity x.next_up() == -(-x).next_down() holds for all non-NaN x. When x is finite x == x.next_up().next_down() also holds.

// f64::EPSILON is the difference between 1.0 and the next number up.
assert_eq!(1.0f64.next_up(), 1.0 + f64::EPSILON);
// But not for most numbers.
assert!(0.1f64.next_up() < 0.1 + f64::EPSILON);
assert_eq!(9007199254740992f64.next_up(), 9007199254740994.0);

This operation corresponds to IEEE-754 nextUp.

1.86.0 · Source

pub fn next_down(self) -> f64

Returns the greatest number less than self.

Let TINY be the smallest representable positive f64. Then,

if self.is_nan(), this returns self;
if self is INFINITY, this returns MAX;
if self is TINY, this returns 0.0;
if self is -0.0 or +0.0, this returns -TINY;
if self is MIN or NEG_INFINITY, this returns NEG_INFINITY;
otherwise the unique greatest value less than self is returned.

The identity x.next_down() == -(-x).next_up() holds for all non-NaN x. When x is finite x == x.next_down().next_up() also holds.

let x = 1.0f64;
// Clamp value into range [0, 1).
let clamped = x.clamp(0.0, 1.0f64.next_down());
assert!(clamped < 1.0);
assert_eq!(clamped.next_up(), 1.0);

This operation corresponds to IEEE-754 nextDown.

1.0.0 · Source

pub fn recip(self) -> f64

Takes the reciprocal (inverse) of a number, 1/x.

let x = 2.0_f64;
let abs_difference = (x.recip() - (1.0 / x)).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn to_degrees(self) -> f64

Converts radians to degrees.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let angle = std::f64::consts::PI;

let abs_difference = (angle.to_degrees() - 180.0).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn to_radians(self) -> f64

Converts degrees to radians.

§Unspecified precision

The precision of this function is non-deterministic. This means it varies by platform, Rust version, and can even differ within the same execution from one invocation to the next.

§Examples

let angle = 180.0_f64;

let abs_difference = (angle.to_radians() - std::f64::consts::PI).abs();

assert!(abs_difference < 1e-10);

1.0.0 · Source

pub fn max(self, other: f64) -> f64

Returns the maximum of the two numbers, ignoring NaN.

If exactly one of the arguments is NaN (quiet or signaling), then the other argument is returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked using the usual rules for arithmetic operations. If the inputs compare equal (such as for the case of +0.0 and -0.0), either input may be returned non-deterministically.

The handling of NaNs follows the IEEE 754-2019 semantics for maximumNumber, treating all NaNs the same way to ensure the operation is associative. The handling of signed zeros follows the IEEE 754-2008 semantics for maxNum.

let x = 1.0_f64;
let y = 2.0_f64;

assert_eq!(x.max(y), y);
assert_eq!(x.max(f64::NAN), x);

1.0.0 · Source

pub fn min(self, other: f64) -> f64

Returns the minimum of the two numbers, ignoring NaN.

If exactly one of the arguments is NaN (quiet or signaling), then the other argument is returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked using the usual rules for arithmetic operations. If the inputs compare equal (such as for the case of +0.0 and -0.0), either input may be returned non-deterministically.

The handling of NaNs follows the IEEE 754-2019 semantics for minimumNumber, treating all NaNs the same way to ensure the operation is associative. The handling of signed zeros follows the IEEE 754-2008 semantics for minNum.

let x = 1.0_f64;
let y = 2.0_f64;

assert_eq!(x.min(y), x);
assert_eq!(x.min(f64::NAN), x);

Source

pub fn maximum(self, other: f64) -> f64

🔬This is a nightly-only experimental API. (float_minimum_maximum)

Returns the maximum of the two numbers, propagating NaN.

If at least one of the arguments is NaN, the return value is NaN, with the bit pattern picked using the usual rules for arithmetic operations. Furthermore, -0.0 is considered to be less than +0.0, making this function fully deterministic for non-NaN inputs.

This is in contrast to f64::max which only returns NaN when both arguments are NaN, and which does not reliably order -0.0 and +0.0.

This follows the IEEE 754-2019 semantics for maximum.

#![feature(float_minimum_maximum)]
let x = 1.0_f64;
let y = 2.0_f64;

assert_eq!(x.maximum(y), y);
assert!(x.maximum(f64::NAN).is_nan());

Source

pub fn minimum(self, other: f64) -> f64

🔬This is a nightly-only experimental API. (float_minimum_maximum)

Returns the minimum of the two numbers, propagating NaN.

If at least one of the arguments is NaN, the return value is NaN, with the bit pattern picked using the usual rules for arithmetic operations. Furthermore, -0.0 is considered to be less than +0.0, making this function fully deterministic for non-NaN inputs.

This is in contrast to f64::min which only returns NaN when both arguments are NaN, and which does not reliably order -0.0 and +0.0.

This follows the IEEE 754-2019 semantics for minimum.

#![feature(float_minimum_maximum)]
let x = 1.0_f64;
let y = 2.0_f64;

assert_eq!(x.minimum(y), x);
assert!(x.minimum(f64::NAN).is_nan());

1.85.0 · Source

pub fn midpoint(self, other: f64) -> f64

Calculates the midpoint (average) between self and rhs.

This returns NaN when either argument is NaN or if a combination of +inf and -inf is provided as arguments.

§Examples

assert_eq!(1f64.midpoint(4.0), 2.5);
assert_eq!((-5.5f64).midpoint(8.0), 1.25);

1.44.0 · Source

pub unsafe fn to_int_unchecked<Int>(self) -> Int
where f64: FloatToInt<Int>,

Rounds toward zero and converts to any primitive integer type, assuming that the value is finite and fits in that type.

let value = 4.6_f64;
let rounded = unsafe { value.to_int_unchecked::<u16>() };
assert_eq!(rounded, 4);

let value = -128.9_f64;
let rounded = unsafe { value.to_int_unchecked::<i8>() };
assert_eq!(rounded, i8::MIN);

§Safety

The value must:

Not be NaN
Not be infinite
Be representable in the return type Int, after truncating off its fractional part

Source

pub fn cast<Flt>(self) -> Flt
where f64: FloatToFloat<Flt>,

🔬This is a nightly-only experimental API. (float_conversions)

Converts to the target float type, rounding as defined in IEEE 754.

This is equivalent to self as Flt. Narrowing to a smaller type can produce an infinity.

#![feature(float_conversions)]

let x = 1.5_f64;
assert_eq!(x.cast::<f32>(), 1.5_f32);

Source

pub fn to_int_saturating<Int>(self) -> Int
where f64: FloatToInt<Int>,

🔬This is a nightly-only experimental API. (float_conversions)

Rounds toward zero and converts to any primitive integer type, saturating at the type’s boundaries and mapping NaN to zero.

This is equivalent to self as Int.

#![feature(float_conversions)]

assert_eq!(255.5_f64.to_int_saturating::<u8>(), 255);
assert_eq!(300.0_f64.to_int_saturating::<u8>(), 255);
assert_eq!((-1.0_f64).to_int_saturating::<u8>(), 0);
assert_eq!(f64::NAN.to_int_saturating::<u8>(), 0);

Source

pub fn to_int_checked<Int>(self) -> Option<Int>
where f64: FloatToInt<Int>,

🔬This is a nightly-only experimental API. (float_conversions)

Rounds toward zero and converts to any primitive integer type, returning None if the value is NaN, infinite, or does not fit in the target type.

#![feature(float_conversions)]

assert_eq!(255.5_f64.to_int_checked::<u8>(), Some(255));
assert_eq!(256.0_f64.to_int_checked::<u8>(), None);
assert_eq!(f64::NAN.to_int_checked::<u8>(), None);

Source

pub fn to_int_strict<Int>(self) -> Int
where f64: FloatToInt<Int>,

🔬This is a nightly-only experimental API. (float_conversions)

Rounds toward zero and converts to any primitive integer type.

This is equivalent to self.to_int_checked().unwrap().

§Panics

Panics if the value is NaN, infinite, or does not fit in the target type.

#![feature(float_conversions)]

assert_eq!(255.5_f64.to_int_strict::<u8>(), 255);

1.20.0 · Source

pub fn to_bits(self) -> u64

Raw transmutation to u64.

This is currently identical to transmute::<f64, u64>(self) on all platforms.

See from_bits for some discussion of the portability of this operation (there are almost no issues).

Note that this function is distinct from as casting, which attempts to preserve the numeric value, and not the bitwise value.

§Examples

assert!((1f64).to_bits() != 1f64 as u64); // to_bits() is not casting!
assert_eq!((12.5f64).to_bits(), 0x4029000000000000);

1.40.0 · Source

pub fn to_be_bytes(self) -> [u8; 8]

Returns the memory representation of this floating point number as a byte array in big-endian (network) byte order.

See from_bits for some discussion of the portability of this operation (there are almost no issues).

§Examples

let bytes = 12.5f64.to_be_bytes();
assert_eq!(bytes, [0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);

1.40.0 · Source

pub fn to_le_bytes(self) -> [u8; 8]

Returns the memory representation of this floating point number as a byte array in little-endian byte order.

See from_bits for some discussion of the portability of this operation (there are almost no issues).

§Examples

let bytes = 12.5f64.to_le_bytes();
assert_eq!(bytes, [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x40]);

1.40.0 · Source

pub fn to_ne_bytes(self) -> [u8; 8]

Returns the memory representation of this floating point number as a byte array in native byte order.

As the target platform’s native endianness is used, portable code should use to_be_bytes or to_le_bytes, as appropriate, instead.

See from_bits for some discussion of the portability of this operation (there are almost no issues).

§Examples

let bytes = 12.5f64.to_ne_bytes();
assert_eq!(
    bytes,
    if cfg!(target_endian = "big") {
        [0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
    } else {
        [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x40]
    }
);

1.62.0 · Source

pub fn total_cmp(&self, other: &f64) -> Ordering

Returns the ordering between self and other.

Unlike the standard partial comparison between floating point numbers, this comparison always produces an ordering in accordance to the totalOrder predicate as defined in the IEEE 754 (2008 revision) floating point standard. The values are ordered in the following sequence:

negative quiet NaN
negative signaling NaN
negative infinity
negative numbers
negative subnormal numbers
negative zero
positive zero
positive subnormal numbers
positive numbers
positive infinity
positive signaling NaN
positive quiet NaN.

The ordering established by this function does not always agree with the PartialOrd and PartialEq implementations of f64. For example, they consider negative and positive zero equal, while total_cmp doesn’t.

The interpretation of the signaling NaN bit follows the definition in the IEEE 754 standard, which may not match the interpretation by some of the older, non-conformant (e.g. MIPS) hardware implementations.

§Example

struct GoodBoy {
    name: String,
    weight: f64,
}

let mut bois = vec![
    GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
    GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
    GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
    GoodBoy { name: "Chonk".to_owned(), weight: f64::INFINITY },
    GoodBoy { name: "Abs. Unit".to_owned(), weight: f64::NAN },
    GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
];

bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));

// `f64::NAN` could be positive or negative, which will affect the sort order.
if f64::NAN.is_sign_negative() {
    assert!(bois.into_iter().map(|b| b.weight)
        .zip([f64::NAN, -5.0, 0.1, 10.0, 99.0, f64::INFINITY].iter())
        .all(|(a, b)| a.to_bits() == b.to_bits()))
} else {
    assert!(bois.into_iter().map(|b| b.weight)
        .zip([-5.0, 0.1, 10.0, 99.0, f64::INFINITY, f64::NAN].iter())
        .all(|(a, b)| a.to_bits() == b.to_bits()))
}

1.50.0 · Source

pub fn clamp(self, min: f64, max: f64) -> f64

Restrict a value to a certain interval unless it is NaN.

Returns max if self is greater than max, and min if self is less than min. Otherwise this returns self.

Note that this function returns NaN if the initial value was NaN as well. If the result is zero and among the three inputs self, min, and max there are zeros with different sign, either 0.0 or -0.0 is returned non-deterministically.

§Panics

Panics if min > max, min is NaN, or max is NaN.

§Examples

assert!((-3.0f64).clamp(-2.0, 1.0) == -2.0);
assert!((0.0f64).clamp(-2.0, 1.0) == 0.0);
assert!((2.0f64).clamp(-2.0, 1.0) == 1.0);
assert!((f64::NAN).clamp(-2.0, 1.0).is_nan());

// These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
assert!((0.0f64).clamp(-0.0, -0.0) == 0.0);
assert!((1.0f64).clamp(-0.0, 0.0) == 0.0);
// This is definitely a negative zero.
assert!((-1.0f64).clamp(-0.0, 1.0).is_sign_negative());

Source

pub fn clamp_magnitude(self, limit: f64) -> f64

🔬This is a nightly-only experimental API. (clamp_magnitude)

Clamps this number to a symmetric range centered around zero.

The method clamps the number’s magnitude (absolute value) to be at most limit.

This is functionally equivalent to self.clamp(-limit, limit), but is more explicit about the intent.

§Panics

Panics if limit is negative or NaN, as this indicates a logic error.

§Examples

#![feature(clamp_magnitude)]
assert_eq!(5.0f64.clamp_magnitude(3.0), 3.0);
assert_eq!((-5.0f64).clamp_magnitude(3.0), -3.0);
assert_eq!(2.0f64.clamp_magnitude(3.0), 2.0);
assert_eq!((-2.0f64).clamp_magnitude(3.0), -2.0);

Source

pub fn clamp_to<R>(self, range: R) -> f64
where R: ClampBounds<f64>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range, unless it is NaN.

This is largely equal to max, min, or clamp, depending on whether the range is min.., ..=max, or min..=max, respectively. However, unlike max and min, it will panic if any bound is NaN.

Note that this function returns NaN if the initial value was NaN as well.

Exclusive ranges are not permitted.

§Panics

Panics on min..=max if min > max, or if any bound is NaN.

§Examples

#![feature(clamp_to)]
assert_eq!((-3.0f64).clamp_to(-2.0..=1.0), -2.0);
assert_eq!(0.0f64.clamp_to(-2.0..=1.0), 0.0);
assert_eq!(2.0f64.clamp_to(..=1.0), 1.0);
assert_eq!(5.0f64.clamp_to(7.0..), 7.0);
assert!(f64::NAN.clamp_to(1.0..=2.0).is_nan());

1.0.0 · Source

pub fn abs(self) -> f64

Computes the absolute value of self.

This function always returns the precise result.

§Examples

let x = 3.5_f64;
let y = -3.5_f64;

assert_eq!(x.abs(), x);
assert_eq!(y.abs(), -y);

assert!(f64::NAN.abs().is_nan());

1.0.0 · Source

pub fn signum(self) -> f64

Returns a number that represents the sign of self.

1.0 if the number is positive, +0.0 or INFINITY
-1.0 if the number is negative, -0.0 or NEG_INFINITY
NaN if the number is NaN

§Examples

let f = 3.5_f64;

assert_eq!(f.signum(), 1.0);
assert_eq!(f64::NEG_INFINITY.signum(), -1.0);

assert!(f64::NAN.signum().is_nan());

1.35.0 · Source

pub fn copysign(self, sign: f64) -> f64

Returns a number composed of the magnitude of self and the sign of sign.

Equal to self if the sign of self and sign are the same, otherwise equal to -self. If self is a NaN, then a NaN with the same payload as self and the sign bit of sign is returned.

If sign is a NaN, then this operation will still carry over its sign into the result. Note that IEEE 754 doesn’t assign any meaning to the sign bit in case of a NaN, and as Rust doesn’t guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the result of copysign with sign being a NaN might produce an unexpected or non-portable result. See the specification of NaN bit patterns for more info.

§Examples

let f = 3.5_f64;

assert_eq!(f.copysign(0.42), 3.5_f64);
assert_eq!(f.copysign(-0.42), -3.5_f64);
assert_eq!((-f).copysign(0.42), 3.5_f64);
assert_eq!((-f).copysign(-0.42), -3.5_f64);

assert!(f64::NAN.copysign(1.0).is_nan());

1.98.0 · Source

pub fn algebraic_add(self, rhs: f64) -> f64

Float addition that allows optimizations based on algebraic rules.

See algebraic operators for more info.

1.98.0 · Source

pub fn algebraic_sub(self, rhs: f64) -> f64

Float subtraction that allows optimizations based on algebraic rules.

See algebraic operators for more info.

1.98.0 · Source

pub fn algebraic_mul(self, rhs: f64) -> f64

Float multiplication that allows optimizations based on algebraic rules.

See algebraic operators for more info.

1.98.0 · Source

pub fn algebraic_div(self, rhs: f64) -> f64

Float division that allows optimizations based on algebraic rules.

See algebraic operators for more info.

1.98.0 · Source

pub fn algebraic_rem(self, rhs: f64) -> f64

Float remainder that allows optimizations based on algebraic rules.

See algebraic operators for more info.

Source

pub fn mul_add_relaxed(self, a: f64, b: f64) -> f64

🔬This is a nightly-only experimental API. (float_mul_add_relaxed)

Computes (self * a) + b with nondeterministic rounding.

This is similar to mul_add, but the intermediate result may be rounded differently depending on the implementation. The operation is either executed as a single fused multiply-add instruction, or as separate multiply and add instructions.

The choice of which one is used is unspecified and non-deterministic: it may vary by target, optimization level, and surrounding code, and even two invocations of this operation with the same inputs may produce different results.

§Precision

The result of this operation is not guaranteed: it is either the result of mul_add (one rounding of the infinite-precision result) or of self * a + b (two roundings, with an intermediate rounding of the product).

§Examples

#![feature(float_mul_add_relaxed)]

// When the fused and unfused operations round differently, either
// result may be returned:
// - 9.020562075079397e-19 is the fused result (one rounding)
// - 1.734723475976807e-18 is the unfused result (two roundings)
let r = 0.1_f64.mul_add_relaxed(0.1_f64, -0.01_f64);
assert!(r == 9.020562075079397e-19 || r == 1.734723475976807e-18);

Source

pub fn nan_to(self, replacement: f64) -> f64

🔬This is a nightly-only experimental API. (float_nan_to)

Returns self if the value is not NaN, otherwise returns replacement if self is NaN.

§Examples

#![feature(float_nan_to)]

let n = f64::NAN;
let x = 2.0f64;
let y = f64::INFINITY;

assert_eq!(n.nan_to(0.0f64), 0.0f64);
assert_eq!(x.nan_to(0.0f64), 2.0f64);
assert_eq!(y.nan_to(0.0f64), f64::INFINITY);

Struct Float64 Copy item path

Tuple Fields§

Methods from Deref<Target = f64>§

pub fn floor(self) -> f64

§Examples

pub fn ceil(self) -> f64

§Examples

pub fn round(self) -> f64

§Examples

pub fn round_ties_even(self) -> f64

§Examples

pub fn trunc(self) -> f64

§Examples

pub fn fract(self) -> f64

§Examples

pub fn mul_add(self, a: f64, b: f64) -> f64

§Precision

§Examples

pub fn div_euclid(self, rhs: f64) -> f64

§Precision

§Examples

pub fn rem_euclid(self, rhs: f64) -> f64

§Precision

§Examples

pub fn powi(self, n: i32) -> f64

§Unspecified precision

§Examples

pub fn powf(self, n: f64) -> f64

§Unspecified precision

§Examples

pub fn sqrt(self) -> f64

§Precision

§Examples

pub fn exp(self) -> f64

§Unspecified precision

§Examples

pub fn exp2(self) -> f64

§Unspecified precision

§Examples

pub fn ln(self) -> f64

§Unspecified precision

§Examples

pub fn log(self, base: f64) -> f64

§Unspecified precision

§Examples

pub fn log2(self) -> f64

§Unspecified precision

§Examples

pub fn log10(self) -> f64

§Unspecified precision

§Examples

pub fn abs_sub(self, other: f64) -> f64

§Unspecified precision

§Examples

pub fn cbrt(self) -> f64

§Unspecified precision

§Examples

pub fn hypot(self, other: f64) -> f64

§Unspecified precision

§Examples

pub fn sin(self) -> f64

§Unspecified precision

§Examples

pub fn cos(self) -> f64

§Unspecified precision

§Examples

pub fn tan(self) -> f64

§Unspecified precision

§Examples

pub fn asin(self) -> f64

§Unspecified precision

§Examples

pub fn acos(self) -> f64

§Unspecified precision

§Examples

pub fn atan(self) -> f64

§Unspecified precision

§Examples

pub fn atan2(self, other: f64) -> f64

§Unspecified precision

Struct Float64