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-rw-r--r--src/pkg/math/pow.go137
1 files changed, 0 insertions, 137 deletions
diff --git a/src/pkg/math/pow.go b/src/pkg/math/pow.go
deleted file mode 100644
index 77af25648..000000000
--- a/src/pkg/math/pow.go
+++ /dev/null
@@ -1,137 +0,0 @@
-// 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
-
-func isOddInt(x float64) bool {
- xi, xf := Modf(x)
- return xf == 0 && int64(xi)&1 == 1
-}
-
-// Special cases taken from FreeBSD's /usr/src/lib/msun/src/e_pow.c
-// updated by IEEE Std. 754-2008 "Section 9.2.1 Special values".
-
-// Pow returns x**y, the base-x exponential of y.
-//
-// Special cases are (in order):
-// Pow(x, ±0) = 1 for any x
-// Pow(1, y) = 1 for any y
-// Pow(x, 1) = x for any x
-// Pow(NaN, y) = NaN
-// Pow(x, NaN) = NaN
-// Pow(±0, y) = ±Inf for y an odd integer < 0
-// Pow(±0, -Inf) = +Inf
-// Pow(±0, +Inf) = +0
-// Pow(±0, y) = +Inf for finite y < 0 and not an odd integer
-// Pow(±0, y) = ±0 for y an odd integer > 0
-// Pow(±0, y) = +0 for finite y > 0 and not an odd integer
-// Pow(-1, ±Inf) = 1
-// Pow(x, +Inf) = +Inf for |x| > 1
-// Pow(x, -Inf) = +0 for |x| > 1
-// Pow(x, +Inf) = +0 for |x| < 1
-// Pow(x, -Inf) = +Inf for |x| < 1
-// Pow(+Inf, y) = +Inf for y > 0
-// Pow(+Inf, y) = +0 for y < 0
-// Pow(-Inf, y) = Pow(-0, -y)
-// Pow(x, y) = NaN for finite x < 0 and finite non-integer y
-func Pow(x, y float64) float64 {
- switch {
- case y == 0 || x == 1:
- return 1
- case y == 1:
- return x
- case y == 0.5:
- return Sqrt(x)
- case y == -0.5:
- return 1 / Sqrt(x)
- case IsNaN(x) || IsNaN(y):
- return NaN()
- case x == 0:
- switch {
- case y < 0:
- if isOddInt(y) {
- return Copysign(Inf(1), x)
- }
- return Inf(1)
- case y > 0:
- if isOddInt(y) {
- return x
- }
- return 0
- }
- case IsInf(y, 0):
- switch {
- case x == -1:
- return 1
- case (Abs(x) < 1) == IsInf(y, 1):
- return 0
- default:
- return Inf(1)
- }
- case IsInf(x, 0):
- if IsInf(x, -1) {
- return Pow(1/x, -y) // Pow(-0, -y)
- }
- switch {
- case y < 0:
- return 0
- case y > 0:
- return Inf(1)
- }
- }
-
- absy := y
- flip := false
- if absy < 0 {
- absy = -absy
- flip = true
- }
- yi, yf := Modf(absy)
- if yf != 0 && x < 0 {
- return NaN()
- }
- if yi >= 1<<63 {
- return Exp(y * Log(x))
- }
-
- // ans = a1 * 2**ae (= 1 for now).
- a1 := 1.0
- ae := 0
-
- // ans *= x**yf
- if yf != 0 {
- if yf > 0.5 {
- yf--
- yi++
- }
- a1 = Exp(yf * Log(x))
- }
-
- // ans *= x**yi
- // by multiplying in successive squarings
- // of x according to bits of yi.
- // accumulate powers of two into exp.
- x1, xe := Frexp(x)
- for i := int64(yi); i != 0; i >>= 1 {
- if i&1 == 1 {
- a1 *= x1
- ae += xe
- }
- x1 *= x1
- xe <<= 1
- if x1 < .5 {
- x1 += x1
- xe--
- }
- }
-
- // ans = a1*2**ae
- // if flip { ans = 1 / ans }
- // but in the opposite order
- if flip {
- a1 = 1 / a1
- ae = -ae
- }
- return Ldexp(a1, ae)
-}