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Diffstat (limited to 'libgo/go/math/pow10.go')
-rw-r--r-- | libgo/go/math/pow10.go | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/libgo/go/math/pow10.go b/libgo/go/math/pow10.go new file mode 100644 index 00000000000..bda2e824ef1 --- /dev/null +++ b/libgo/go/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] + } +} |