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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
// Ldexp is the inverse of Frexp.
// It returns frac × 2**exp.
func Ldexp(frac float64, exp int) float64 {
// TODO(rsc): Remove manual inlining of IsNaN, IsInf
// when compiler does it for us
// special cases
switch {
case frac == 0:
return frac // correctly return -0
case frac != frac: // IsNaN(frac):
return NaN()
}
x := Float64bits(frac)
exp += int(x>>shift) & mask
if exp <= 0 {
return 0 // underflow
}
if exp >= mask { // overflow
if frac < 0 {
return Inf(-1)
}
return Inf(1)
}
x &^= mask << shift
x |= uint64(exp) << shift
return Float64frombits(x)
}
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