1 files changed, 84 insertions, 0 deletions
diff --git a/sysdeps/generic/s_catanh.c b/sysdeps/generic/s_catanh.c
new file mode 100644
index 0000000000..0cb852a069
--- /dev/null
+++ b/sysdeps/generic/s_catanh.c
@@ -0,0 +1,84 @@
+/* Return arc hyperbole tangent for double value.
+   Copyright (C) 1997 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <complex.h>
+#include <math.h>
+
+#include "math_private.h"
+
+
+__complex__ double
+__catanh (__complex__ double x)
+{
+  __complex__ double res;
+  int rcls = fpclassify (__real__ x);
+  int icls = fpclassify (__imag__ x);
+
+  if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
+    {
+      if (icls == FP_INFINITE)
+	{
+	  __real__ res = __copysign (0.0, __real__ x);
+	  __imag__ res = __copysign (M_PI_2, __imag__ x);
+	}
+      else if (rcls == FP_INFINITE || rcls == FP_ZERO)
+	{
+	  __real__ res = __copysign (0.0, __real__ x);
+	  if (icls >= FP_ZERO)
+	    __imag__ res = __copysign (M_PI_2, __imag__ x);
+	  else
+	    __imag__ res = __nan ("");
+	}
+      else
+	{
+	  __real__ res = __nan ("");
+	  __imag__ res = __nan ("");
+	}
+    }
+  else if (rcls == FP_ZERO && icls == FP_ZERO)
+    {
+      res = x;
+    }
+  else
+    {
+      double i2, num, den;
+
+      i2 = __imag__ x * __imag__ x;
+
+      num = 1.0 + __real__ x;
+      num = i2 + num * num;
+
+      den = 1.0 - __real__ x;
+      den = i2 + den * den;
+
+      __real__ res = 0.25 * (__ieee754_log (num) - __ieee754_log (den));
+
+      den = 1 - __real__ x * __real__ x - i2;
+
+      __imag__ res = 0.5 * __ieee754_atan2 (2.0 * __imag__ x, den);
+    }
+
+  return res;
+}
+weak_alias (__catanh, catanh)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__catanh, __catanhl)
+weak_alias (__catanh, catanhl)
+#endif