From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001
From: upstream source tree <ports@midipix.org>
Date: Sun, 15 Mar 2015 20:14:05 -0400
Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified
 gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream
 tarball.

downloading a git-generated archive based on the 'upstream' tag
should provide you with a source tree that is binary identical
to the one extracted from the above tarball.

if you have obtained the source via the command 'git clone',
however, do note that line-endings of files in your working
directory might differ from line-endings of the respective
files in the upstream repository.
---
 libgo/go/math/acosh.go | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 libgo/go/math/acosh.go

(limited to 'libgo/go/math/acosh.go')

diff --git a/libgo/go/math/acosh.go b/libgo/go/math/acosh.go
new file mode 100644
index 000000000..d8067c065
--- /dev/null
+++ b/libgo/go/math/acosh.go
@@ -0,0 +1,62 @@
+// Copyright 2010 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 original C code, the long comment, and the constants
+// below are from FreeBSD's /usr/src/lib/msun/src/e_acosh.c
+// and came with this notice.  The go code is a simplified
+// version of the original C.
+//
+// ====================================================
+// Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+//
+// Developed at SunPro, a Sun Microsystems, Inc. business.
+// Permission to use, copy, modify, and distribute this
+// software is freely granted, provided that this notice
+// is preserved.
+// ====================================================
+//
+//
+// __ieee754_acosh(x)
+// Method :
+//	Based on
+//	        acosh(x) = log [ x + sqrt(x*x-1) ]
+//	we have
+//	        acosh(x) := log(x)+ln2,	if x is large; else
+//	        acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x>2; else
+//	        acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t=x-1.
+//
+// Special cases:
+//	acosh(x) is NaN with signal if x<1.
+//	acosh(NaN) is NaN without signal.
+//
+
+// Acosh(x) calculates the inverse hyperbolic cosine of x.
+//
+// Special cases are:
+//	Acosh(x) = NaN if x < 1
+//	Acosh(NaN) = NaN
+func Acosh(x float64) float64 {
+	const (
+		Ln2   = 6.93147180559945286227e-01 // 0x3FE62E42FEFA39EF
+		Large = 1 << 28                    // 2**28
+	)
+	// TODO(rsc): Remove manual inlining of IsNaN
+	// when compiler does it for us
+	// first case is special case
+	switch {
+	case x < 1 || x != x: // x < 1 || IsNaN(x):
+		return NaN()
+	case x == 1:
+		return 0
+	case x >= Large:
+		return Log(x) + Ln2 // x > 2**28
+	case x > 2:
+		return Log(2*x - 1/(x+Sqrt(x*x-1))) // 2**28 > x > 2
+	}
+	t := x - 1
+	return Log1p(t + Sqrt(2*t+t*t)) // 2 >= x > 1
+}
-- 
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