blob: 99b318e78f51268eba88beee80db10a694826c64 [file] [log] [blame]
// 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.
* it is important to get all one can from this
* routine since it is used in atof to scale numbers.
* the presumption is that GO converts fp numbers better
* than multipication of lower powers of 10.
*/
var pow10tab [70]float64
// Pow10 returns 10**x, the base-10 exponential of x.
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]
}
}