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 // Copyright 2017 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package runtime import "unsafe" var inf = float64frombits(0x7FF0000000000000) // isNaN reports whether f is an IEEE 754 “not-a-number” value. func isNaN(f float64) (is bool) { // IEEE 754 says that only NaNs satisfy f != f. return f != f } // isFinite reports whether f is neither NaN nor an infinity. func isFinite(f float64) bool { return !isNaN(f - f) } // isInf reports whether f is an infinity. func isInf(f float64) bool { return !isNaN(f) && !isFinite(f) } // Abs returns the absolute value of x. // // Special cases are: // // Abs(±Inf) = +Inf // Abs(NaN) = NaN func abs(x float64) float64 { const sign = 1 << 63 return float64frombits(float64bits(x) &^ sign) } // copysign returns a value with the magnitude // of x and the sign of y. func copysign(x, y float64) float64 { const sign = 1 << 63 return float64frombits(float64bits(x)&^sign | float64bits(y)&sign) } // Float64bits returns the IEEE 754 binary representation of f. func float64bits(f float64) uint64 { return *(*uint64)(unsafe.Pointer(&f)) } // Float64frombits returns the floating point number corresponding // the IEEE 754 binary representation b. func float64frombits(b uint64) float64 { return *(*float64)(unsafe.Pointer(&b)) }