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The Math.f16round()
static method returns the nearest 16-bit half precision float representation of a number.
console.log(Math.f16round(5.5));
// Expected output: 5.5
console.log(Math.f16round(5.05));
// Expected output: 5.05078125
console.log(Math.f16round(5));
// Expected output: 5
console.log(Math.f16round(-5.05));
// Expected output: -5.05078125
Syntax
Math.f16round(doubleFloat)
Parameters Return value
The nearest 16-bit half precision float representation of doubleFloat
.
Math.f16round
is the 16-bit counterpart of Math.fround()
. It is intended to smooth some rough edges when interacting with float16 numbers, such as when reading from a Float16Array
. Internally, JavaScript continues to treat the number as a 64-bit float, it just performs a "round to even" on the 10th bit of the mantissa, and sets all following mantissa bits to 0
. If the number is outside the range of a 16-bit float, Infinity
or -Infinity
is returned.
Because f16round()
is a static method of Math
, you always use it as Math.f16round()
, rather than as a method of a Math
object you created (Math
is not a constructor).
The number 1.5 can be precisely represented in the binary numeral system, and is identical in 16-bit and 64-bit:
Math.f16round(1.5); // 1.5
Math.f16round(1.5) === 1.5; // true
However, the number 1.337 cannot be precisely represented in the binary numeral system, so it differs in 16-bit and 64-bit:
Math.f16round(1.337); // 1.3369140625
Math.f16round(1.337) === 1.337; // false
100000 is too big for a 16-bit float, so Infinity
is returned:
Math.f16round(100000); // Infinity
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