Source: floor.go in package math


package math

Floor returns the greatest integer value less than or equal to x. Special cases are: Floor(±0) = ±0 Floor(±Inf) = ±Inf Floor(NaN) = NaN

func Floor(x float64) float64

func floor(x float64) float64 {
	if x == 0 || IsNaN(x) || IsInf(x, 0) {
		return x
	}
	if x < 0 {
		d, fract := Modf(-x)
		if fract != 0.0 {
			d = d + 1
		}
		return -d
	}
	d, _ := Modf(x)
	return d
}

Ceil returns the least integer value greater than or equal to x. Special cases are: Ceil(±0) = ±0 Ceil(±Inf) = ±Inf Ceil(NaN) = NaN

func Ceil(x float64) float64

func ceil(x float64) float64 {
	return -Floor(-x)
}

Trunc returns the integer value of x. Special cases are: Trunc(±0) = ±0 Trunc(±Inf) = ±Inf Trunc(NaN) = NaN

func Trunc(x float64) float64

func trunc(x float64) float64 {
	if x == 0 || IsNaN(x) || IsInf(x, 0) {
		return x
	}
	d, _ := Modf(x)
	return d
}

Round returns the nearest integer, rounding half away from zero. Special cases are: Round(±0) = ±0 Round(±Inf) = ±Inf Round(NaN) = NaN

Round is a faster implementation of: func Round(x float64) float64 { t := Trunc(x) if Abs(x-t) >= 0.5 { return t + Copysign(1, x) } return t }

	bits := Float64bits(x)
	e := uint(bits>>shift) & mask

Round abs(x) < 1 including denormals.

		bits &= signMask // +-0
		if e == bias-1 {
			bits |= uvone // +-1
		}

Round any abs(x) >= 1 containing a fractional component [0,1). Numbers with larger exponents are returned unchanged since they must be either an integer, infinity, or NaN.

		const half = 1 << (shift - 1)
		e -= bias
		bits += half >> e
		bits &^= fracMask >> e
	}
	return Float64frombits(bits)
}

RoundToEven returns the nearest integer, rounding ties to even. Special cases are: RoundToEven(±0) = ±0 RoundToEven(±Inf) = ±Inf RoundToEven(NaN) = NaN

RoundToEven is a faster implementation of: func RoundToEven(x float64) float64 { t := math.Trunc(x) odd := math.Remainder(t, 2) != 0 if d := math.Abs(x - t); d > 0.5 || (d == 0.5 && odd) { return t + math.Copysign(1, x) } return t }

	bits := Float64bits(x)
	e := uint(bits>>shift) & mask

Round abs(x) >= 1. - Large numbers without fractional components, infinity, and NaN are unchanged. - Add 0.499.. or 0.5 before truncating depending on whether the truncated number is even or odd (respectively).

		const halfMinusULP = (1 << (shift - 1)) - 1
		e -= bias
		bits += (halfMinusULP + (bits>>(shift-e))&1) >> e
		bits &^= fracMask >> e

Round 0.5 < abs(x) < 1.

		bits = bits&signMask | uvone // +-1

Round abs(x) <= 0.5 including denormals.

		bits &= signMask // +-0
	}
	return Float64frombits(bits)