2.5-18.1

1 files changed, 90 insertions, 0 deletions

diff --git a/sysdeps/ieee754/ldbl-128ibm/e_coshl.c b/sysdeps/ieee754/ldbl-128ibm/e_coshl.c
new file mode 100644
index 0000000..73cb478
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-128ibm/e_coshl.c
@@ -0,0 +1,90 @@
+/* @(#)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 long double one = 1.0L, half=0.5L, huge = 1.0e300L;
+#else
+static long double one = 1.0L, half=0.5L, huge = 1.0e300L;
+#endif
+
+#ifdef __STDC__
+	long double __ieee754_coshl(long double x)
+#else
+	long double __ieee754_coshl(x)
+	long double x;
+#endif
+{
+	long double t,w;
+	int64_t ix;
+
+    /* High word of |x|. */
+	GET_LDOUBLE_MSW64(ix,x);
+	ix &= 0x7fffffffffffffffLL;
+
+    /* x is INF or NaN */
+	if(ix>=0x7ff0000000000000LL) return x*x;
+
+    /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
+	if(ix<0x3fd62e42fefa39efLL) {
+	    t = __expm1l(fabsl(x));
+	    w = one+t;
+	    if (ix<0x3c80000000000000LL) 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 < 0x4036000000000000LL) {
+		t = __ieee754_expl(fabsl(x));
+		return half*t+half/t;
+	}
+
+    /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
+	if (ix < 0x40862e42fefa39efLL)  return half*__ieee754_expl(fabsl(x));
+
+    /* |x| in [log(maxdouble), overflowthresold] */
+        if (ix < 0x408633ce8fb9f87dLL) {
+	    w = __ieee754_expl(half*fabsl(x));
+	    t = half*w;
+	    return t*w;
+	}
+
+    /* |x| > overflowthresold, cosh(x) overflow */
+	return huge*huge;
+}