1 files changed, 69 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_acoshl.c b/sysdeps/ieee754/ldbl-128ibm/e_acoshl.c
new file mode 100644
index 0000000000..00576c76c8
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-128ibm/e_acoshl.c
@@ -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 long double
+#else
+static long double
+#endif
+one	= 1.0L,
+ln2	= 6.93147180559945286227e-01L;  /* 0x3FE62E42, 0xFEFA39EF */
+
+#ifdef __STDC__
+	long double __ieee754_acoshl(long double x)
+#else
+	long double __ieee754_acoshl(x)
+	long double x;
+#endif
+{
+	long double t;
+	int64_t hx;
+	u_int64_t lx;
+	GET_LDOUBLE_WORDS64(hx,lx,x);
+	if(hx<0x3ff0000000000000LL) {		/* x < 1 */
+	    return (x-x)/(x-x);
+	} else if(hx >=0x41b0000000000000LL) {	/* x > 2**28 */
+	    if(hx >=0x7ff0000000000000LL) {	/* x is inf of NaN */
+	        return x+x;
+	    } else
+		return __ieee754_logl(x)+ln2;	/* acosh(huge)=log(2x) */
+	} else if (((hx-0x3ff0000000000000LL)|(lx&0x7fffffffffffffffLL))==0) {
+	    return 0.0;			/* acosh(1) = 0 */
+	} else if (hx > 0x4000000000000000LL) {	/* 2**28 > x > 2 */
+	    t=x*x;
+	    return __ieee754_logl(2.0*x-one/(x+__ieee754_sqrtl(t-one)));
+	} else {			/* 1<x<2 */
+	    t = x-one;
+	    return __log1p(t+__sqrtl(2.0*t+t*t));
+	}
+}