Imported Upstream version 1.4upstream/1.4

1 files changed, 0 insertions, 76 deletions

diff --git a/src/pkg/math/cbrt.go b/src/pkg/math/cbrt.go
deleted file mode 100644
index 272e30923..000000000
--- a/src/pkg/math/cbrt.go
+++ /dev/null
@@ -1,76 +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
-
-/*
-	The algorithm is based in part on "Optimal Partitioning of
-	Newton's Method for Calculating Roots", by Gunter Meinardus
-	and G. D. Taylor, Mathematics of Computation © 1980 American
-	Mathematical Society.
-	(http://www.jstor.org/stable/2006387?seq=9, accessed 11-Feb-2010)
-*/
-
-// Cbrt returns the cube root of x.
-//
-// Special cases are:
-//	Cbrt(±0) = ±0
-//	Cbrt(±Inf) = ±Inf
-//	Cbrt(NaN) = NaN
-func Cbrt(x float64) float64 {
-	const (
-		A1 = 1.662848358e-01
-		A2 = 1.096040958e+00
-		A3 = 4.105032829e-01
-		A4 = 5.649335816e-01
-		B1 = 2.639607233e-01
-		B2 = 8.699282849e-01
-		B3 = 1.629083358e-01
-		B4 = 2.824667908e-01
-		C1 = 4.190115298e-01
-		C2 = 6.904625373e-01
-		C3 = 6.46502159e-02
-		C4 = 1.412333954e-01
-	)
-	// special cases
-	switch {
-	case x == 0 || IsNaN(x) || IsInf(x, 0):
-		return x
-	}
-	sign := false
-	if x < 0 {
-		x = -x
-		sign = true
-	}
-	// Reduce argument and estimate cube root
-	f, e := Frexp(x) // 0.5 <= f < 1.0
-	m := e % 3
-	if m > 0 {
-		m -= 3
-		e -= m // e is multiple of 3
-	}
-	switch m {
-	case 0: // 0.5 <= f < 1.0
-		f = A1*f + A2 - A3/(A4+f)
-	case -1:
-		f *= 0.5 // 0.25 <= f < 0.5
-		f = B1*f + B2 - B3/(B4+f)
-	default: // m == -2
-		f *= 0.25 // 0.125 <= f < 0.25
-		f = C1*f + C2 - C3/(C4+f)
-	}
-	y := Ldexp(f, e/3) // e/3 = exponent of cube root
-
-	// Iterate
-	s := y * y * y
-	t := s + x
-	y *= (t + x) / (s + t)
-	// Reiterate
-	s = (y*y*y - x) / x
-	y -= y * (((14.0/81.0)*s-(2.0/9.0))*s + (1.0 / 3.0)) * s
-	if sign {
-		y = -y
-	}
-	return y
-}