[−][src]Struct half::f16

#[repr(transparent)]pub struct f16(_);

A 16-bit floating point type implementing the IEEE 754-2008 standard binary16 a.k.a half format.

This 16-bit floating point type is intended for efficient storage where the full range and precision of a larger floating point value is not required. Because f16 is primarily for efficient storage, floating point operations such as addition, multiplication, etc. are not implemented. Operations should be performed with f32 or higher-precision types and converted to/from f16 as necessary.

Implementations

`impl f16`[src]

`pub const fn from_bits(bits: u16) -> f16`[src]

Constructs a 16-bit floating point value from the raw bits.

`pub fn from_f32(value: f32) -> f16`[src]

Constructs a 16-bit floating point value from a 32-bit floating point value.

If the 32-bit value is to large to fit in 16-bits, ±∞ will result. NaN values are preserved. 32-bit subnormal values are too tiny to be represented in 16-bits and result in ±0. Exponents that underflow the minimum 16-bit exponent will result in 16-bit subnormals or ±0. All other values are truncated and rounded to the nearest representable 16-bit value.

`pub fn from_f64(value: f64) -> f16`[src]

Constructs a 16-bit floating point value from a 64-bit floating point value.

If the 64-bit value is to large to fit in 16-bits, ±∞ will result. NaN values are preserved. 64-bit subnormal values are too tiny to be represented in 16-bits and result in ±0. Exponents that underflow the minimum 16-bit exponent will result in 16-bit subnormals or ±0. All other values are truncated and rounded to the nearest representable 16-bit value.

`pub const fn to_bits(self) -> u16`[src]

Converts a f16 into the underlying bit representation.

`pub fn to_le_bytes(self) -> [u8; 2]`[src]

Return the memory representation of the underlying bit representation as a byte array in little-endian byte order.

Examples

let bytes = f16::from_f32(12.5).to_le_bytes();
assert_eq!(bytes, [0x40, 0x4A]);

`pub fn to_be_bytes(self) -> [u8; 2]`[src]

Return the memory representation of the underlying bit representation as a byte array in big-endian (network) byte order.

Examples

let bytes = f16::from_f32(12.5).to_be_bytes();
assert_eq!(bytes, [0x4A, 0x40]);

`pub fn to_ne_bytes(self) -> [u8; 2]`[src]

Return the memory representation of the underlying bit representation 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.

Examples

let bytes = f16::from_f32(12.5).to_ne_bytes();
assert_eq!(bytes, if cfg!(target_endian = "big") {
    [0x4A, 0x40]
} else {
    [0x40, 0x4A]
});

`pub fn from_le_bytes(bytes: [u8; 2]) -> f16`[src]

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

Examples

let value = f16::from_le_bytes([0x40, 0x4A]);
assert_eq!(value, f16::from_f32(12.5));

`pub fn from_be_bytes(bytes: [u8; 2]) -> f16`[src]

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

Examples

let value = f16::from_be_bytes([0x4A, 0x40]);
assert_eq!(value, f16::from_f32(12.5));

`pub fn from_ne_bytes(bytes: [u8; 2]) -> f16`[src]

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.

Examples

let value = f16::from_ne_bytes(if cfg!(target_endian = "big") {
    [0x4A, 0x40]
} else {
    [0x40, 0x4A]
});
assert_eq!(value, f16::from_f32(12.5));

`pub fn as_bits(self) -> u16`[src]

👎 Deprecated since 1.2.0:

renamed to to_bits

Converts a f16 into the underlying bit representation.

`pub fn to_f32(self) -> f32`[src]

Converts a f16 value into a f32 value.

This conversion is lossless as all 16-bit floating point values can be represented exactly in 32-bit floating point.

`pub fn to_f64(self) -> f64`[src]

Converts a f16 value into a f64 value.

This conversion is lossless as all 16-bit floating point values can be represented exactly in 64-bit floating point.

`pub const fn is_nan(self) -> bool`[src]

Returns true if this value is NaN and false otherwise.

Examples


let nan = f16::NAN;
let f = f16::from_f32(7.0_f32);

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

`pub const fn is_infinite(self) -> bool`[src]

Returns true if this value is ±∞ and false otherwise.

Examples


let f = f16::from_f32(7.0f32);
let inf = f16::INFINITY;
let neg_inf = f16::NEG_INFINITY;
let nan = f16::NAN;

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

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

`pub const fn is_finite(self) -> bool`[src]

Returns true if this number is neither infinite nor NaN.

Examples


let f = f16::from_f32(7.0f32);
let inf = f16::INFINITY;
let neg_inf = f16::NEG_INFINITY;
let nan = f16::NAN;

assert!(f.is_finite());

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

`pub fn is_normal(self) -> bool`[src]

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

Examples


let min = f16::MIN_POSITIVE;
let max = f16::MAX;
let lower_than_min = f16::from_f32(1.0e-10_f32);
let zero = f16::from_f32(0.0_f32);

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

assert!(!zero.is_normal());
assert!(!f16::NAN.is_normal());
assert!(!f16::INFINITY.is_normal());
// Values between `0` and `min` are Subnormal.
assert!(!lower_than_min.is_normal());

`pub fn classify(self) -> FpCategory`[src]

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.

Examples

use std::num::FpCategory;

let num = f16::from_f32(12.4_f32);
let inf = f16::INFINITY;

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

`pub fn signum(self) -> f16`[src]

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 = f16::from_f32(3.5_f32);

assert_eq!(f.signum(), f16::from_f32(1.0));
assert_eq!(f16::NEG_INFINITY.signum(), f16::from_f32(-1.0));

assert!(f16::NAN.signum().is_nan());

`pub const fn is_sign_positive(self) -> bool`[src]

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

Examples


let nan = f16::NAN;
let f = f16::from_f32(7.0_f32);
let g = f16::from_f32(-7.0_f32);

assert!(f.is_sign_positive());
assert!(!g.is_sign_positive());
// `NaN` can be either positive or negative
assert!(nan.is_sign_positive() != nan.is_sign_negative());

`pub const fn is_sign_negative(self) -> bool`[src]

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

Examples


let nan = f16::NAN;
let f = f16::from_f32(7.0f32);
let g = f16::from_f32(-7.0f32);

assert!(!f.is_sign_negative());
assert!(g.is_sign_negative());
// `NaN` can be either positive or negative
assert!(nan.is_sign_positive() != nan.is_sign_negative());