golang abs 代码
文件路径：/src/math/abs.go
/ 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
/ Abs returns the absolute value of x.
/
/ Special cases are:
/
/ Abs(±Inf) = +Inf
/ Abs(NaN) = NaN
func Abs(x float64) float64 {
return Float64frombits(Float64bits(x) &^ (1 << 63))
}