std::f64

Returns true if this value is NaN and false otherwise.

use std::f64;

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

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

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

use std::f64;

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());

Returns true if this number is neither infinite nor NaN.

use std::f64;

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());

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

use std::f64;

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());

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;
use std::f64;

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

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

Returns the largest integer less than or equal to a number.

let f = 3.99_f64;
let g = 3.0_f64;

assert_eq!(f.floor(), 3.0);
assert_eq!(g.floor(), 3.0);

Returns the smallest integer greater than or equal to a number.

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

assert_eq!(f.ceil(), 4.0);
assert_eq!(g.ceil(), 4.0);

Returns the nearest integer to a number. Round half-way cases away from 0.0.

let f = 3.3_f64;
let g = -3.3_f64;

assert_eq!(f.round(), 3.0);
assert_eq!(g.round(), -3.0);

Returns the integer part of a number.

let f = 3.3_f64;
let g = -3.7_f64;

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

Returns the fractional part of a number.

let x = 3.5_f64;
let y = -3.5_f64;
let abs_difference_x = (x.fract() - 0.5).abs();
let abs_difference_y = (y.fract() - (-0.5)).abs();

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

Computes the absolute value of self. Returns NAN if the number is NAN.

use std::f64;

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

let abs_difference_x = (x.abs() - x).abs();
let abs_difference_y = (y.abs() - (-y)).abs();

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

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

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

use std::f64;

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());

Returns true if self's sign bit is positive, including +0.0 and INFINITY.

use std::f64;

let nan: f64 = f64::NAN;

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

assert!(f.is_sign_positive());
assert!(!g.is_sign_positive());
// Requires both tests to determine if is `NaN`
assert!(!nan.is_sign_positive() && !nan.is_sign_negative());

Returns true if self's sign is negative, including -0.0 and NEG_INFINITY.

use std::f64;

let nan = f64::NAN;

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

assert!(!f.is_sign_negative());
assert!(g.is_sign_negative());
// Requires both tests to determine if is `NaN`.
assert!(!nan.is_sign_positive() && !nan.is_sign_negative());

Fused multiply-add. Computes (self * a) + b with only one rounding error. This produces a more accurate result with better performance than a separate multiplication operation followed by an add.

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

// 100.0
let abs_difference = (m.mul_add(x, b) - (m*x + b)).abs();

assert!(abs_difference < 1e-10);

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);

Raises a number to an integer power.

Using this function is generally faster than using powf

let x = 2.0_f64;
let abs_difference = (x.powi(2) - x*x).abs();

assert!(abs_difference < 1e-10);

Raises a number to a floating point power.

let x = 2.0_f64;
let abs_difference = (x.powf(2.0) - x*x).abs();

assert!(abs_difference < 1e-10);

Takes the square root of a number.

Returns NaN if self is a negative number.

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

let abs_difference = (positive.sqrt() - 2.0).abs();

assert!(abs_difference < 1e-10);
assert!(negative.sqrt().is_nan());

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

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);

Returns 2^(self).

let f = 2.0_f64;

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

assert!(abs_difference < 1e-10);

Returns the natural logarithm of the number.

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);

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

let ten = 10.0_f64;
let two = 2.0_f64;

// log10(10) - 1 == 0
let abs_difference_10 = (ten.log(10.0) - 1.0).abs();

// log2(2) - 1 == 0
let abs_difference_2 = (two.log(2.0) - 1.0).abs();

assert!(abs_difference_10 < 1e-10);
assert!(abs_difference_2 < 1e-10);

Returns the base 2 logarithm of the number.

let two = 2.0_f64;

// log2(2) - 1 == 0
let abs_difference = (two.log2() - 1.0).abs();

assert!(abs_difference < 1e-10);

Returns the base 10 logarithm of the number.

let ten = 10.0_f64;

// log10(10) - 1 == 0
let abs_difference = (ten.log10() - 1.0).abs();

assert!(abs_difference < 1e-10);

Converts radians to degrees.

use std::f64::consts;

let angle = consts::PI;

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

assert!(abs_difference < 1e-10);

Converts degrees to radians.

use std::f64::consts;

let angle = 180.0_f64;

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

assert!(abs_difference < 1e-10);

Returns the maximum of the two numbers.

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

assert_eq!(x.max(y), y);

If one of the arguments is NaN, then the other argument is returned.

Returns the minimum of the two numbers.

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

assert_eq!(x.min(y), x);

If one of the arguments is NaN, then the other argument is returned.

The positive difference of two numbers.

• If self <= other: 0:0
• Else: self - other

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);

Takes the cubic root of a number.

let x = 8.0_f64;

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

assert!(abs_difference < 1e-10);

Calculates the length of the hypotenuse of a right-angle triangle given legs of length x and y.

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);

Computes the sine of a number (in radians).

use std::f64;

let x = f64::consts::PI/2.0;

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

assert!(abs_difference < 1e-10);

Computes the cosine of a number (in radians).

use std::f64;

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

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

assert!(abs_difference < 1e-10);

Computes the tangent of a number (in radians).

use std::f64;

let x = f64::consts::PI/4.0;
let abs_difference = (x.tan() - 1.0).abs();

assert!(abs_difference < 1e-14);

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].

use std::f64;

let f = f64::consts::PI / 2.0;

// asin(sin(pi/2))
let abs_difference = (f.sin().asin() - f64::consts::PI / 2.0).abs();

assert!(abs_difference < 1e-10);

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].

use std::f64;

let f = f64::consts::PI / 4.0;

// acos(cos(pi/4))
let abs_difference = (f.cos().acos() - f64::consts::PI / 4.0).abs();

assert!(abs_difference < 1e-10);

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

let f = 1.0_f64;

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

assert!(abs_difference < 1e-10);

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

• x = 0, y = 0: 0
• x >= 0: arctan(y/x) -> [-pi/2, pi/2]
• y >= 0: arctan(y/x) + pi -> (pi/2, pi]
• y < 0: arctan(y/x) - pi -> (-pi, -pi/2)

use std::f64;

let pi = f64::consts::PI;
// All angles from horizontal right (+x)
// 45 deg counter-clockwise
let x1 = 3.0_f64;
let y1 = -3.0_f64;

// 135 deg clockwise
let x2 = -3.0_f64;
let y2 = 3.0_f64;

let abs_difference_1 = (y1.atan2(x1) - (-pi/4.0)).abs();
let abs_difference_2 = (y2.atan2(x2) - 3.0*pi/4.0).abs();

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

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

use std::f64;

let x = f64::consts::PI/4.0;
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);

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

let x = 7.0_f64;

// e^(ln(7)) - 1
let abs_difference = (x.ln().exp_m1() - 6.0).abs();

assert!(abs_difference < 1e-10);

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

use std::f64;

let x = f64::consts::E - 1.0;

// ln(1 + (e - 1)) == ln(e) == 1
let abs_difference = (x.ln_1p() - 1.0).abs();

assert!(abs_difference < 1e-10);

Hyperbolic sine function.

use std::f64;

let e = 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);

Hyperbolic cosine function.

use std::f64;

let e = 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);

Hyperbolic tangent function.

use std::f64;

let e = 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);

Inverse hyperbolic sine function.

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

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

assert!(abs_difference < 1.0e-10);

Inverse hyperbolic cosine function.

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

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

assert!(abs_difference < 1.0e-10);

Inverse hyperbolic tangent function.

use std::f64;

let e = f64::consts::E;
let f = e.tanh().atanh();

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

assert!(abs_difference < 1.0e-10);

Raw transmutation to u64.

Converts the f64 into its raw memory representation, similar to the transmute function.

Note that this function is distinct from casting.

Examples

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

Raw transmutation from u64.

Converts the given u64 containing the float's raw memory representation into the f64 type, similar to the transmute function.

There is only one difference to a bare transmute: Due to the implications onto Rust's safety promises being uncertain, if the representation of a signaling NaN "sNaN" float is passed to the function, the implementation is allowed to return a quiet NaN instead.

Note that this function is distinct from casting.

Examples

#![feature(float_bits_conv)]
use std::f64;
let v = f64::from_bits(0x4029000000000000);
let difference = (v - 12.5).abs();
assert!(difference <= 1e-5);
// Example for a signaling NaN value:
let snan = 0x7FF0000000000001;
assert_ne!(f64::from_bits(snan).to_bits(), snan);

The resulting type after applying the + operator

The method for the + operator

The resulting type after applying the + operator

The method for the + operator

The resulting type after applying the + operator

The method for the + operator

The resulting type after applying the + operator

The method for the + operator

Returns the "default value" for a type. Read more

Method which takes an iterator and generates Self from the elements by "summing up" the items. Read more

Method which takes an iterator and generates Self from the elements by "summing up" the items. Read more

Formats the value using the given formatter.

The resulting type after applying the * operator

The method for the * operator

The resulting type after applying the * operator

The method for the * operator

The resulting type after applying the * operator

The method for the * operator

The resulting type after applying the * operator

The method for the * operator

The method for the /= operator

The method for the -= operator

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

Method which takes an iterator and generates Self from the elements by multiplying the items. Read more

Method which takes an iterator and generates Self from the elements by multiplying the items. Read more

Returns a deep copy of the value.

Performs copy-assignment from source. Read more

This method returns an ordering between self and other values if one exists. Read more

This method tests less than (for self and other) and is used by the < operator. Read more

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

This method tests greater than (for self and other) and is used by the > operator. Read more

The resulting type after applying the - operator

The method for the unary - operator

The resulting type after applying the - operator

The method for the unary - operator

Formats the value using the given formatter.

Formats the value using the given formatter. Read more

The resulting type after applying the - operator

The method for the - operator

The resulting type after applying the - operator

The method for the - operator

The resulting type after applying the - operator

The method for the - operator

The resulting type after applying the - operator

The method for the - operator

The associated error which can be returned from parsing.

Converts a string in base 10 to a float. Accepts an optional decimal exponent.

This function accepts strings such as

• '3.14'
• '-3.14'
• '2.5E10', or equivalently, '2.5e10'
• '2.5E-10'
• '.' (understood as 0)
• '5.'
• '.5', or, equivalently, '0.5'
• 'inf', '-inf', 'NaN'

Leading and trailing whitespace represent an error.

Arguments

• src - A string

Return value

Err(ParseFloatError) if the string did not represent a valid number. Otherwise, Ok(n) where n is the floating-point number represented by src.

The resulting type after applying the % operator

The method for the % operator

The resulting type after applying the % operator

The method for the % operator

The resulting type after applying the % operator

The method for the % operator

The resulting type after applying the % operator

The method for the % operator

The method for the %= operator

The method for the *= operator

The method for the += operator

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Formats the value using the given formatter.

The resulting type after applying the / operator

The method for the / operator

The resulting type after applying the / operator

The method for the / operator

The resulting type after applying the / operator

The method for the / operator

The resulting type after applying the / operator

The method for the / operator