1 files changed, 89 insertions, 0 deletions
diff --git a/math/s_catan.c b/math/s_catan.c
new file mode 100644
index 0000000000..1d0673ad6a
--- /dev/null
+++ b/math/s_catan.c
@@ -0,0 +1,89 @@
+/* Return arc tangent of complex 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 Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; 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
+__catan (__complex__ double x)
+{
+  __complex__ double res;
+  int rcls = fpclassify (__real__ x);
+  int icls = fpclassify (__imag__ x);
+
+  if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
+    {
+      if (rcls == FP_INFINITE)
+	{
+	  __real__ res = __copysign (M_PI_2, __real__ x);
+	  __imag__ res = __copysign (0.0, __imag__ x);
+	}
+      else if (icls == FP_INFINITE)
+	{
+	  if (rcls >= FP_ZERO)
+	    __real__ res = __copysign (M_PI_2, __real__ x);
+	  else
+	    __real__ res = __nan ("");
+	  __imag__ res = __copysign (0.0, __imag__ x);
+	}
+      else if (icls == FP_ZERO || icls == FP_INFINITE)
+	{
+	  __real__ res = __nan ("");
+	  __imag__ res = __copysign (0.0, __imag__ x);
+	}
+      else
+	{
+	  __real__ res = __nan ("");
+	  __imag__ res = __nan ("");
+	}
+    }
+  else if (rcls == FP_ZERO && icls == FP_ZERO)
+    {
+      res = x;
+    }
+  else
+    {
+      double r2, num, den;
+
+      r2 = __real__ x * __real__ x;
+
+      den = 1 - r2 - __imag__ x * __imag__ x;
+
+      __real__ res = 0.5 * __ieee754_atan2 (2.0 * __real__ x, den);
+
+      num = __imag__ x + 1.0;
+      num = r2 + num * num;
+
+      den = __imag__ x - 1.0;
+      den = r2 + den * den;
+
+      __imag__ res = 0.25 * __ieee754_log (num / den);
+    }
+
+  return res;
+}
+weak_alias (__catan, catan)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__catan, __catanl)
+weak_alias (__catan, catanl)
+#endif