af146490bb
It is not needed due to the removal of the ctx field.
Reviewed-on: https://go-review.googlesource.com/16525
From-SVN: r229616
37 lines
837 B
Go
37 lines
837 B
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
|
|
|
|
// Log10 returns the decimal logarithm of x.
|
|
// The special cases are the same as for Log.
|
|
|
|
//extern log10
|
|
func libc_log10(float64) float64
|
|
|
|
func Log10(x float64) float64 {
|
|
return libc_log10(x)
|
|
}
|
|
|
|
func log10(x float64) float64 {
|
|
return Log(x) * (1 / Ln10)
|
|
}
|
|
|
|
// Log2 returns the binary logarithm of x.
|
|
// The special cases are the same as for Log.
|
|
|
|
func Log2(x float64) float64 {
|
|
return log2(x)
|
|
}
|
|
|
|
func log2(x float64) float64 {
|
|
frac, exp := Frexp(x)
|
|
// Make sure exact powers of two give an exact answer.
|
|
// Don't depend on Log(0.5)*(1/Ln2)+exp being exactly exp-1.
|
|
if frac == 0.5 {
|
|
return float64(exp - 1)
|
|
}
|
|
return Log(frac)*(1/Ln2) + float64(exp)
|
|
}
|