From 109be507377fe7f6e8819ac94041d3fdcdf6fd2f Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 28 Apr 2024 15:18:25 +0200 Subject: Adding upstream version 1.19.8. Signed-off-by: Daniel Baumann --- src/math/log10.go | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 src/math/log10.go (limited to 'src/math/log10.go') diff --git a/src/math/log10.go b/src/math/log10.go new file mode 100644 index 0000000..e6916a5 --- /dev/null +++ b/src/math/log10.go @@ -0,0 +1,37 @@ +// 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. +func Log10(x float64) float64 { + if haveArchLog10 { + return archLog10(x) + } + return 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 { + if haveArchLog2 { + return archLog2(x) + } + 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) +} -- cgit v1.2.3