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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.
//
// Special cases are:
// Pow10(e) = +Inf for e > 309
// Pow10(e) = 0 for e < -324
func Pow10(e int) float64 {
if e <= -325 {
return 0
} else if e > 309 {
return Inf(1)
}
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]
}
}
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