1 files changed, 71 insertions, 0 deletions
diff --git a/usr/src/lib/libm/common/C/atanh.c b/usr/src/lib/libm/common/C/atanh.c
new file mode 100644
index 0000000000..48ff800e65
--- /dev/null
+++ b/usr/src/lib/libm/common/C/atanh.c
@@ -0,0 +1,71 @@
+/*
+ * 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 atanh = __atanh
+
+/* INDENT OFF */
+/*
+ * atanh(x)
+ * Code originated from 4.3bsd.
+ * Modified by K.C. Ng for SUN 4.0 libm.
+ * Method :
+ *                  1              2x                          x
+ *	atanh(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------)
+ *                  2             1 - x                      1 - x
+ * Note: to guarantee atanh(-x) = -atanh(x), we use
+ *                 sign(x)             |x|
+ *	atanh(x) = ------- * log1p(2*-------).
+ *                    2              1 - |x|
+ *
+ * Special cases:
+ *	atanh(x) is NaN if |x| > 1 with signal;
+ *	atanh(NaN) is that NaN with no signal;
+ *	atanh(+-1) is +-INF with signal.
+ */
+/* INDENT ON */
+
+#include "libm.h"
+#include "libm_synonyms.h"
+#include "libm_protos.h"
+#include <math.h>
+
+double
+atanh(double x) {
+	double t;
+
+	if (isnan(x))
+		return (x * x);		/* switched from x + x for Cheetah */
+	t = fabs(x);
+	if (t > 1.0)
+		return (_SVID_libm_err(x, x, 30));	/* sNaN */
+	if (t == 1.0)
+		return (_SVID_libm_err(x, x, 31));	/* x/0; */
+	t = t / (1.0 - t);
+	return (copysign(0.5, x) * log1p(t + t));
+}