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authorRoland McGrath <roland@gnu.org>1996-03-05 21:41:30 +0000
committerRoland McGrath <roland@gnu.org>1996-03-05 21:41:30 +0000
commitf7eac6eb504f4baf13dbb4d26717942df050ebe6 (patch)
tree95ff129c06c7f6f246a5e2bfa489ba6382659d19 /sysdeps/libm-ieee754/e_acosh.c
parent1521668f2afae1dc2ef5d7ffaeb84353b36874dd (diff)
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Mon Mar 4 20:54:40 1996 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* Makeconfig ($(common-objpfx)config.make): Depend on config.h.in. Mon Mar 4 17:35:09 1996 Roland McGrath <roland@charlie-brown.gnu.ai.mit.edu> * hurd/catch-signal.c (hurd_safe_memmove): New function. (hurd_safe_copyin, hurd_safe_copyout): New functions. * hurd/hurd/sigpreempt.h: Declare them. Sun Mar 3 08:43:44 1996 Roland McGrath <roland@charlie-brown.gnu.ai.mit.edu> Replace math code with fdlibm from Sun as modified for netbsd by JT Conklin and Ian Taylor, including x86 FPU support. * sysdeps/libm-ieee754, sysdeps/libm-i387: New directories. * math/math_private.h: New file. * sysdeps/i386/fpu/Implies: New file. * sysdeps/ieee754/Implies: New file. * math/machine/asm.h, math/machine/endian.h: New files. * math/Makefile, math/math.h: Rewritten. * mathcalls.h, math/mathcalls.h: New file, broken out of math.h. * math/finite.c: File removed. * sysdeps/generic/Makefile [$(subdir)=math]: Frobnication removed. * math/test-math.c: Include errno.h and string.h. * sysdeps/unix/bsd/dirstream.h: File removed. * sysdeps/unix/bsd/readdir.c: File removed.
Diffstat (limited to 'sysdeps/libm-ieee754/e_acosh.c')
-rw-r--r--sysdeps/libm-ieee754/e_acosh.c69
1 files changed, 69 insertions, 0 deletions
diff --git a/sysdeps/libm-ieee754/e_acosh.c b/sysdeps/libm-ieee754/e_acosh.c
new file mode 100644
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@@ -0,0 +1,69 @@
+/* @(#)e_acosh.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+#if defined(LIBM_SCCS) && !defined(lint)
+static char rcsid[] = "$NetBSD: e_acosh.c,v 1.9 1995/05/12 04:57:18 jtc Exp $";
+#endif
+
+/* __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.
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const double
+#else
+static double
+#endif
+one = 1.0,
+ln2 = 6.93147180559945286227e-01; /* 0x3FE62E42, 0xFEFA39EF */
+
+#ifdef __STDC__
+ double __ieee754_acosh(double x)
+#else
+ double __ieee754_acosh(x)
+ double x;
+#endif
+{
+ double t;
+ int32_t hx;
+ u_int32_t lx;
+ EXTRACT_WORDS(hx,lx,x);
+ if(hx<0x3ff00000) { /* x < 1 */
+ return (x-x)/(x-x);
+ } else if(hx >=0x41b00000) { /* x > 2**28 */
+ if(hx >=0x7ff00000) { /* x is inf of NaN */
+ return x+x;
+ } else
+ return __ieee754_log(x)+ln2; /* acosh(huge)=log(2x) */
+ } else if(((hx-0x3ff00000)|lx)==0) {
+ return 0.0; /* acosh(1) = 0 */
+ } else if (hx > 0x40000000) { /* 2**28 > x > 2 */
+ t=x*x;
+ return __ieee754_log(2.0*x-one/(x+__ieee754_sqrt(t-one)));
+ } else { /* 1<x<2 */
+ t = x-one;
+ return __log1p(t+__sqrt(2.0*t+t*t));
+ }
+}