about summary refs log tree commit diff
path: root/sysdeps/libm-ieee754/e_cosh.c
diff options
context:
space:
mode:
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_cosh.c
parent1521668f2afae1dc2ef5d7ffaeb84353b36874dd (diff)
downloadglibc-f7eac6eb504f4baf13dbb4d26717942df050ebe6.tar.gz
glibc-f7eac6eb504f4baf13dbb4d26717942df050ebe6.tar.xz
glibc-f7eac6eb504f4baf13dbb4d26717942df050ebe6.zip
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_cosh.c')
-rw-r--r--sysdeps/libm-ieee754/e_cosh.c93
1 files changed, 93 insertions, 0 deletions
diff --git a/sysdeps/libm-ieee754/e_cosh.c b/sysdeps/libm-ieee754/e_cosh.c
new file mode 100644
index 0000000000..4f6b52435b
--- /dev/null
+++ b/sysdeps/libm-ieee754/e_cosh.c
@@ -0,0 +1,93 @@
+/* @(#)e_cosh.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_cosh.c,v 1.7 1995/05/10 20:44:58 jtc Exp $";
+#endif
+
+/* __ieee754_cosh(x)
+ * Method : 
+ * mathematically cosh(x) if defined to be (exp(x)+exp(-x))/2
+ *	1. Replace x by |x| (cosh(x) = cosh(-x)). 
+ *	2. 
+ *		                                        [ exp(x) - 1 ]^2 
+ *	    0        <= x <= ln2/2  :  cosh(x) := 1 + -------------------
+ *			       			           2*exp(x)
+ *
+ *		                                  exp(x) +  1/exp(x)
+ *	    ln2/2    <= x <= 22     :  cosh(x) := -------------------
+ *			       			          2
+ *	    22       <= x <= lnovft :  cosh(x) := exp(x)/2 
+ *	    lnovft   <= x <= ln2ovft:  cosh(x) := exp(x/2)/2 * exp(x/2)
+ *	    ln2ovft  <  x	    :  cosh(x) := huge*huge (overflow)
+ *
+ * Special cases:
+ *	cosh(x) is |x| if x is +INF, -INF, or NaN.
+ *	only cosh(0)=1 is exact for finite x.
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const double one = 1.0, half=0.5, huge = 1.0e300;
+#else
+static double one = 1.0, half=0.5, huge = 1.0e300;
+#endif
+
+#ifdef __STDC__
+	double __ieee754_cosh(double x)
+#else
+	double __ieee754_cosh(x)
+	double x;
+#endif
+{	
+	double t,w;
+	int32_t ix;
+	u_int32_t lx;
+
+    /* High word of |x|. */
+	GET_HIGH_WORD(ix,x);
+	ix &= 0x7fffffff;
+
+    /* x is INF or NaN */
+	if(ix>=0x7ff00000) return x*x;	
+
+    /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
+	if(ix<0x3fd62e43) {
+	    t = __expm1(fabs(x));
+	    w = one+t;
+	    if (ix<0x3c800000) return w;	/* cosh(tiny) = 1 */
+	    return one+(t*t)/(w+w);
+	}
+
+    /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
+	if (ix < 0x40360000) {
+		t = __ieee754_exp(fabs(x));
+		return half*t+half/t;
+	}
+
+    /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
+	if (ix < 0x40862E42)  return half*__ieee754_exp(fabs(x));
+
+    /* |x| in [log(maxdouble), overflowthresold] */
+	GET_LOW_WORD(lx,x);
+	if (ix<0x408633CE || 
+	      (ix==0x408633ce)&&(lx<=(u_int32_t)0x8fb9f87d)) {
+	    w = __ieee754_exp(half*fabs(x));
+	    t = half*w;
+	    return t*w;
+	}
+
+    /* |x| > overflowthresold, cosh(x) overflow */
+	return huge*huge;
+}