# Primitive Type f64

1.0.0 ·## Expand description

A 64-bit floating point type (specifically, the “binary64” type defined in IEEE 754-2008).

This type is very similar to `f32`

, but has increased
precision by using twice as many bits. Please see the documentation for
`f32`

or Wikipedia on double precision
values for more information.

## Implementations§

source§### impl f64

### impl f64

1.43.0 · source#### pub const MANTISSA_DIGITS: u32 = 53u32

#### pub const MANTISSA_DIGITS: u32 = 53u32

Number of significant digits in base 2.

1.43.0 · source#### pub const DIGITS: u32 = 15u32

#### pub const DIGITS: u32 = 15u32

Approximate number of significant digits in base 10.

This is the maximum *x* such that any decimal number with *x*
significant digits can be converted to `f64`

and back without loss.

Equal to floor(log_{10} 2^{MANTISSA_DIGITS − 1}).

1.43.0 · source#### pub const EPSILON: f64 = 2.2204460492503131E-16f64

#### pub const EPSILON: f64 = 2.2204460492503131E-16f64

Machine epsilon value for `f64`

.

This is the difference between `1.0`

and the next larger representable number.

Equal to 2^{1 − MANTISSA_DIGITS}.

1.43.0 · source#### pub const MIN: f64 = -1.7976931348623157E+308f64

#### pub const MIN: f64 = -1.7976931348623157E+308f64

Smallest finite `f64`

value.

Equal to −`MAX`

.

1.43.0 · source#### pub const MIN_POSITIVE: f64 = 2.2250738585072014E-308f64

#### pub const MIN_POSITIVE: f64 = 2.2250738585072014E-308f64

Smallest positive normal `f64`

value.

Equal to 2^{MIN_EXP − 1}.

1.43.0 · source#### pub const MAX: f64 = 1.7976931348623157E+308f64

#### pub const MAX: f64 = 1.7976931348623157E+308f64

Largest finite `f64`

value.

Equal to
(1 − 2^{−MANTISSA_DIGITS}) 2^{MAX_EXP}.

1.43.0 · source#### pub const MIN_EXP: i32 = -1_021i32

#### pub const MIN_EXP: i32 = -1_021i32

One greater than the minimum possible normal power of 2 exponent.

If *x* = `MIN_EXP`

, then normal numbers
≥ 0.5 × 2^{x}.

1.43.0 · source#### pub const MAX_EXP: i32 = 1_024i32

#### pub const MAX_EXP: i32 = 1_024i32

Maximum possible power of 2 exponent.

If *x* = `MAX_EXP`

, then normal numbers
< 1 × 2^{x}.

1.43.0 · source#### pub const MIN_10_EXP: i32 = -307i32

#### pub const MIN_10_EXP: i32 = -307i32

Minimum *x* for which 10^{x} is normal.

Equal to ceil(log_{10} `MIN_POSITIVE`

).

1.43.0 · source#### pub const MAX_10_EXP: i32 = 308i32

#### pub const MAX_10_EXP: i32 = 308i32

Maximum *x* for which 10^{x} is normal.

Equal to floor(log_{10} `MAX`

).

1.43.0 · source#### pub const NAN: f64 = NaNf64

#### pub const NAN: f64 = NaNf64

Not a Number (NaN).

Note that IEEE 754 doesn’t define just a single NaN value; a plethora of bit patterns are considered to be NaN. Furthermore, the standard makes a difference between a “signaling” and a “quiet” NaN, and allows inspecting its “payload” (the unspecified bits in the bit pattern). This constant isn’t guaranteed to equal to any specific NaN bitpattern, and the stability of its representation over Rust versions and target platforms isn’t guaranteed.

1.43.0 · source#### pub const NEG_INFINITY: f64 = -Inff64

#### pub const NEG_INFINITY: f64 = -Inff64

Negative infinity (−∞).

const: unstable · source#### pub fn is_nan(self) -> bool

#### 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());
```

Runconst: unstable · source#### pub fn is_infinite(self) -> bool

#### 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());
```

Runconst: unstable · source#### pub fn is_finite(self) -> bool

#### 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());
```

Run1.53.0 (const: unstable) · source#### pub fn is_subnormal(self) -> bool

#### 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());
```

Runconst: unstable · source#### pub fn is_normal(self) -> bool

#### 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());
```

Runconst: unstable · source#### pub fn classify(self) -> FpCategory

#### 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);
```

Runconst: unstable · source#### pub fn is_sign_positive(self) -> bool

#### 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 result in some cases.
See explanation of NaN as a special value for more info.

```
let f = 7.0_f64;
let g = -7.0_f64;
assert!(f.is_sign_positive());
assert!(!g.is_sign_positive());
```

Runconst: unstable · source#### pub fn is_sign_negative(self) -> bool

#### 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 result in some cases.
See explanation of NaN as a special value for more info.

```
let f = 7.0_f64;
let g = -7.0_f64;
assert!(!f.is_sign_negative());
assert!(g.is_sign_negative());
```

Runconst: unstable · source#### pub fn next_up(self) -> Self

🔬This is a nightly-only experimental API. (`float_next_up_down`

#91399)

#### pub fn next_up(self) -> Self

`float_next_up_down`

#91399)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.

```
#![feature(float_next_up_down)]
// 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);
```

Runconst: unstable · source#### pub fn next_down(self) -> Self

🔬This is a nightly-only experimental API. (`float_next_up_down`

#91399)

#### pub fn next_down(self) -> Self

`float_next_up_down`

#91399)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.

```
#![feature(float_next_up_down)]
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);
```

Runsource#### pub fn recip(self) -> f64

#### 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);
```

Runsource#### pub fn to_degrees(self) -> f64

#### pub fn to_degrees(self) -> f64

Converts radians to degrees.

```
let angle = std::f64::consts::PI;
let abs_difference = (angle.to_degrees() - 180.0).abs();
assert!(abs_difference < 1e-10);
```

Runsource#### pub fn to_radians(self) -> f64

#### pub fn to_radians(self) -> f64

Converts degrees to radians.

```
let angle = 180.0_f64;
let abs_difference = (angle.to_radians() - std::f64::consts::PI).abs();
assert!(abs_difference < 1e-10);
```

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

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

Returns the maximum of the two numbers, ignoring NaN.

If one of the arguments is NaN, then the other argument is returned. This follows the IEEE 754-2008 semantics for maxNum, except for handling of signaling NaNs; this function handles all NaNs the same way and avoids maxNum’s problems with associativity. This also matches the behavior of libm’s fmax.

```
let x = 1.0_f64;
let y = 2.0_f64;
assert_eq!(x.max(y), y);
```

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

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

Returns the minimum of the two numbers, ignoring NaN.

If one of the arguments is NaN, then the other argument is returned. This follows the IEEE 754-2008 semantics for minNum, except for handling of signaling NaNs; this function handles all NaNs the same way and avoids minNum’s problems with associativity. This also matches the behavior of libm’s fmin.

```
let x = 1.0_f64;
let y = 2.0_f64;
assert_eq!(x.min(y), x);
```

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

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

#91079)

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

`float_minimum_maximum`

#91079)Returns the maximum of the two numbers, propagating NaN.

This returns NaN when *either* argument is NaN, as opposed to
`f64::max`

which only returns NaN when *both* arguments are NaN.

```
#![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());
```

RunIf one of the arguments is NaN, then NaN is returned. Otherwise this returns the greater of the two numbers. For this operation, -0.0 is considered to be less than +0.0. Note that this follows the semantics specified in IEEE 754-2019.

Also note that “propagation” of NaNs here doesn’t necessarily mean that the bitpattern of a NaN operand is conserved; see explanation of NaN as a special value for more info.

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

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

#91079)

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

`float_minimum_maximum`

#91079)Returns the minimum of the two numbers, propagating NaN.

This returns NaN when *either* argument is NaN, as opposed to
`f64::min`

which only returns NaN when *both* arguments are NaN.

```
#![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());
```

RunIf one of the arguments is NaN, then NaN is returned. Otherwise this returns the lesser of the two numbers. For this operation, -0.0 is considered to be less than +0.0. Note that this follows the semantics specified in IEEE 754-2019.

Also note that “propagation” of NaNs here doesn’t necessarily mean that the bitpattern of a NaN operand is conserved; see explanation of NaN as a special value for more info.

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

🔬This is a nightly-only experimental API. (`num_midpoint`

#110840)

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

`num_midpoint`

#110840)1.44.0 · source#### pub unsafe fn to_int_unchecked<Int>(self) -> Intwhere
Self: FloatToInt<Int>,

#### pub unsafe fn to_int_unchecked<Int>(self) -> Intwhere Self: 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);
```

Run##### Safety

The value must:

- Not be
`NaN`

- Not be infinite
- Be representable in the return type
`Int`

, after truncating off its fractional part

1.20.0 (const: unstable) · source#### pub fn to_bits(self) -> u64

#### 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);
```

Run1.20.0 (const: unstable) · source#### pub fn from_bits(v: u64) -> Self

#### pub fn from_bits(v: u64) -> Self

Raw transmutation from `u64`

.

This is currently identical to `transmute::<u64, f64>(v)`

on all platforms.
It turns out this is incredibly portable, for two reasons:

- Floats and Ints have the same endianness on all supported platforms.
- IEEE 754 very precisely specifies the bit layout of floats.

However there is one caveat: prior to the 2008 version of IEEE 754, how to interpret the NaN signaling bit wasn’t actually specified. Most platforms (notably x86 and ARM) picked the interpretation that was ultimately standardized in 2008, but some didn’t (notably MIPS). As a result, all signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.

Rather than trying to preserve signaling-ness cross-platform, this implementation favors preserving the exact bits. This means that any payloads encoded in NaNs will be preserved even if the result of this method is sent over the network from an x86 machine to a MIPS one.

If the results of this method are only manipulated by the same architecture that produced them, then there is no portability concern.

If the input isn’t NaN, then there is no portability concern.

If you don’t care about signaling-ness (very likely), then there is no portability concern.

Note that this function is distinct from `as`

casting, which attempts to
preserve the *numeric* value, and not the bitwise value.

##### Examples

```
let v = f64::from_bits(0x4029000000000000);
assert_eq!(v, 12.5);
```

Run1.40.0 (const: unstable) · source#### pub fn to_be_bytes(self) -> [u8; 8]

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

Return 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]);
```

Run1.40.0 (const: unstable) · source#### pub fn to_le_bytes(self) -> [u8; 8]

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

Return 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]);
```

Run1.40.0 (const: unstable) · source#### pub fn to_ne_bytes(self) -> [u8; 8]

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

Return 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]
}
);
```

Run1.40.0 (const: unstable) · source#### pub fn from_be_bytes(bytes: [u8; 8]) -> Self

#### pub fn from_be_bytes(bytes: [u8; 8]) -> Self

Create a floating point value from its representation as a byte array in big endian.

See `from_bits`

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

##### Examples

```
let value = f64::from_be_bytes([0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);
assert_eq!(value, 12.5);
```

Run1.40.0 (const: unstable) · source#### pub fn from_le_bytes(bytes: [u8; 8]) -> Self

#### pub fn from_le_bytes(bytes: [u8; 8]) -> Self

Create a floating point value from its representation as a byte array in little endian.

See `from_bits`

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

##### Examples

```
let value = f64::from_le_bytes([0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x40]);
assert_eq!(value, 12.5);
```

Run1.40.0 (const: unstable) · source#### pub fn from_ne_bytes(bytes: [u8; 8]) -> Self

#### pub fn from_ne_bytes(bytes: [u8; 8]) -> Self

Create a floating point value from its representation as a byte array in native endian.

As the target platform’s native endianness is used, portable code
likely wants to use `from_be_bytes`

or `from_le_bytes`

, as
appropriate instead.

See `from_bits`

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

##### Examples

```
let value = f64::from_ne_bytes(if cfg!(target_endian = "big") {
[0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
} else {
[0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x40]
});
assert_eq!(value, 12.5);
```

Run1.62.0 · source#### pub fn total_cmp(&self, other: &Self) -> Ordering

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

Return 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));
```

Run1.50.0 · source#### pub fn clamp(self, min: f64, max: f64) -> f64

#### 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.

##### 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());
```

Run## Trait Implementations§

1.22.0 · source§### impl AddAssign<&f64> for f64

### impl AddAssign<&f64> for f64

source§#### fn add_assign(&mut self, other: &f64)

#### fn add_assign(&mut self, other: &f64)

`+=`

operation. Read more1.8.0 · source§### impl AddAssign for f64

### impl AddAssign for f64

source§#### fn add_assign(&mut self, other: f64)

#### fn add_assign(&mut self, other: f64)

`+=`

operation. Read more1.22.0 · source§### impl DivAssign<&f64> for f64

### impl DivAssign<&f64> for f64

source§#### fn div_assign(&mut self, other: &f64)

#### fn div_assign(&mut self, other: &f64)

`/=`

operation. Read more1.8.0 · source§### impl DivAssign for f64

### impl DivAssign for f64

source§#### fn div_assign(&mut self, other: f64)

#### fn div_assign(&mut self, other: f64)

`/=`

operation. Read moresource§### impl FromStr for f64

### impl FromStr for f64

source§#### fn from_str(src: &str) -> Result<Self, ParseFloatError>

#### fn from_str(src: &str) -> Result<Self, ParseFloatError>

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’
- ‘5.’
- ‘.5’, or, equivalently, ‘0.5’
- ‘inf’, ‘-inf’, ‘+infinity’, ‘NaN’

Note that alphabetical characters are not case-sensitive.

Leading and trailing whitespace represent an error.

##### Grammar

All strings that adhere to the following EBNF grammar when
lowercased will result in an `Ok`

being returned:

```
Float ::= Sign? ( 'inf' | 'infinity' | 'nan' | Number )
Number ::= ( Digit+ |
Digit+ '.' Digit* |
Digit* '.' Digit+ ) Exp?
Exp ::= 'e' Sign? Digit+
Sign ::= [+-]
Digit ::= [0-9]
```

##### Arguments

- src - A string

##### Return value

`Err(ParseFloatError)`

if the string did not represent a valid
number. Otherwise, `Ok(n)`

where `n`

is the closest
representable floating-point number to the number represented
by `src`

(following the same rules for rounding as for the
results of primitive operations).

§#### type Err = ParseFloatError

#### type Err = ParseFloatError

1.22.0 · source§### impl MulAssign<&f64> for f64

### impl MulAssign<&f64> for f64

source§#### fn mul_assign(&mut self, other: &f64)

#### fn mul_assign(&mut self, other: &f64)

`*=`

operation. Read more1.8.0 · source§### impl MulAssign for f64

### impl MulAssign for f64

source§#### fn mul_assign(&mut self, other: f64)

#### fn mul_assign(&mut self, other: f64)

`*=`

operation. Read moresource§### impl PartialOrd for f64

### impl PartialOrd for f64

source§#### fn le(&self, other: &f64) -> bool

#### fn le(&self, other: &f64) -> bool

`self`

and `other`

) and is used by the `<=`

operator. Read moresource§### impl Rem for f64

### impl Rem for f64

The remainder from the division of two floats.

The remainder has the same sign as the dividend and is computed as:
`x - (x / y).trunc() * y`

.

#### Examples

```
let x: f32 = 50.50;
let y: f32 = 8.125;
let remainder = x - (x / y).trunc() * y;
// The answer to both operations is 1.75
assert_eq!(x % y, remainder);
```

Run1.22.0 · source§### impl RemAssign<&f64> for f64

### impl RemAssign<&f64> for f64

source§#### fn rem_assign(&mut self, other: &f64)

#### fn rem_assign(&mut self, other: &f64)

`%=`

operation. Read more1.8.0 · source§### impl RemAssign for f64

### impl RemAssign for f64

source§#### fn rem_assign(&mut self, other: f64)

#### fn rem_assign(&mut self, other: f64)

`%=`

operation. Read moresource§### impl SimdElement for f64

### impl SimdElement for f64

1.22.0 · source§### impl SubAssign<&f64> for f64

### impl SubAssign<&f64> for f64

source§#### fn sub_assign(&mut self, other: &f64)

#### fn sub_assign(&mut self, other: &f64)

`-=`

operation. Read more1.8.0 · source§### impl SubAssign for f64

### impl SubAssign for f64

source§#### fn sub_assign(&mut self, other: f64)

#### fn sub_assign(&mut self, other: f64)

`-=`

operation. Read more