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// Copyright 2009 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 math
// Frexp breaks f into a normalized fraction
// and an integral power of two.
// It returns frac and exp satisfying f == frac × 2**exp,
// with the absolute value of frac in the interval [½, 1).
//
// Special cases are:
// Frexp(±0) = ±0, 0
// Frexp(±Inf) = ±Inf, 0
// Frexp(NaN) = NaN, 0
func Frexp(f float64) (frac float64, exp int) {
// TODO(rsc): Remove manual inlining of IsNaN, IsInf
// when compiler does it for us
// special cases
switch {
case f == 0:
return f, 0 // correctly return -0
case f < -MaxFloat64 || f > MaxFloat64 || f != f: // IsInf(f, 0) || IsNaN(f):
return f, 0
}
f, exp = normalize(f)
x := Float64bits(f)
exp += int((x>>shift)&mask) - bias + 1
x &^= mask << shift
x |= (-1 + bias) << shift
frac = Float64frombits(x)
return
}
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