From 5ff4c17907d5b19510a62e08fd8d3b11e62b431d Mon Sep 17 00:00:00 2001 From: Ondřej Surý Date: Tue, 13 Sep 2011 13:13:40 +0200 Subject: Imported Upstream version 60 --- src/pkg/math/pow10.go | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 src/pkg/math/pow10.go (limited to 'src/pkg/math/pow10.go') diff --git a/src/pkg/math/pow10.go b/src/pkg/math/pow10.go new file mode 100644 index 000000000..bda2e824e --- /dev/null +++ b/src/pkg/math/pow10.go @@ -0,0 +1,30 @@ +// 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 + +// This table might overflow 127-bit exponent representations. +// In that case, truncate it after 1.0e38. +var pow10tab [70]float64 + +// Pow10 returns 10**e, the base-10 exponential of e. +func Pow10(e int) float64 { + if e < 0 { + return 1 / Pow10(-e) + } + if e < len(pow10tab) { + return pow10tab[e] + } + m := e / 2 + return Pow10(m) * Pow10(e-m) +} + +func init() { + pow10tab[0] = 1.0e0 + pow10tab[1] = 1.0e1 + for i := 2; i < len(pow10tab); i++ { + m := i / 2 + pow10tab[i] = pow10tab[m] * pow10tab[i-m] + } +} -- cgit v1.2.3