1 files changed, 96 insertions, 0 deletions
diff --git a/usr/src/lib/libm/common/C/acosh.c b/usr/src/lib/libm/common/C/acosh.c
new file mode 100644
index 0000000000..7eecfe635e
--- /dev/null
+++ b/usr/src/lib/libm/common/C/acosh.c
@@ -0,0 +1,96 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
+ */
+/*
+ * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#pragma weak acosh = __acosh
+
+/* INDENT OFF */
+/*
+ * 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.
+ */
+/* INDENT ON */
+
+#include "libm_synonyms.h"	/* __acosh, __log, __log1p */
+#include "libm_protos.h"	/* _SVID_libm_error */
+#include "libm_macros.h"
+#include <math.h>
+
+static const double
+	one = 1.0,
+	ln2 = 6.93147180559945286227e-01;	/* 3FE62E42, FEFA39EF */
+
+double
+acosh(double x) {
+	double t;
+	int hx;
+
+	hx = ((int *) &x)[HIWORD];
+	if (hx < 0x3ff00000) {	/* x < 1 */
+		if (isnan(x))
+#if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
+			return (hx >= 0xfff80000 ? x : (x - x) / (x - x));
+			/* assumes sparc-like QNaN */
+#else
+			return (x - x) / (x - x);
+#endif
+		else
+			return (_SVID_libm_err(x, x, 29));
+	} else if (hx >= 0x41b00000) {
+		/* x > 2**28 */
+		if (hx >= 0x7ff00000) {	/* x is inf of NaN */
+#if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
+			return (hx >= 0x7ff80000 ? x : x + x);
+			/* assumes sparc-like QNaN */
+#else
+			return (x + x);
+#endif
+		} else	/* acosh(huge)=log(2x) */
+			return (log(x) + ln2);
+	} else if (((hx - 0x3ff00000) | ((int *) &x)[LOWORD]) == 0) {
+		return (0.0);	/* acosh(1) = 0 */
+	} else if (hx > 0x40000000) {
+		/* 2**28 > x > 2 */
+		t = x * x;
+		return (log(2.0 * x - one / (x + sqrt(t - one))));
+	} else {
+		/* 1 < x < 2 */
+		t = x - one;
+		return (log1p(t + sqrt(2.0 * t + t * t)));
+	}
+}