libgo/go/math/abs.go

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package math
   6
   7 // Abs returns the absolute value of x.
   8 //
   9 // Special cases are:
  10 //      Abs(±Inf) = +Inf
  11 //      Abs(NaN) = NaN
  12
  13 //extern fabs
  14 func libc_fabs(float64) float64
  15
  16 func Abs(x float64) float64 {
  17         return libc_fabs(x)
  18 }
  19
  20 func abs(x float64) float64 {
  21         // TODO: once golang.org/issue/13095 is fixed, change this to:
  22         // return Float64frombits(Float64bits(x) &^ (1 << 63))
  23         // But for now, this generates better code and can also be inlined:
  24         if x < 0 {
  25                 return -x
  26         }
  27         if x == 0 {
  28                 return 0 // return correctly abs(-0)
  29         }
  30         return x
  31 }