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Diffstat (limited to 'libgo/go/math/pow10.go')
-rw-r--r--libgo/go/math/pow10.go30
1 files changed, 30 insertions, 0 deletions
diff --git a/libgo/go/math/pow10.go b/libgo/go/math/pow10.go
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+++ b/libgo/go/math/pow10.go
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+// 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]
+ }
+}