1 files changed, 84 insertions, 0 deletions
diff --git a/math/s_ctan.c b/math/s_ctan.c
new file mode 100644
index 0000000..0464ab8
--- /dev/null
+++ b/math/s_ctan.c
@@ -0,0 +1,84 @@
+/* Complex tangent function for double.
+   Copyright (C) 1997, 2005 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 <fenv.h>
+#include <math.h>
+
+#include "math_private.h"
+
+
+__complex__ double
+__ctan (__complex__ double x)
+{
+  __complex__ double res;
+
+  if (!isfinite (__real__ x) || !isfinite (__imag__ x))
+    {
+      if (__isinf (__imag__ x))
+	{
+	  __real__ res = __copysign (0.0, __real__ x);
+	  __imag__ res = __copysign (1.0, __imag__ x);
+	}
+      else if (__real__ x == 0.0)
+	{
+	  res = x;
+	}
+      else
+	{
+	  __real__ res = __nan ("");
+	  __imag__ res = __nan ("");
+
+#ifdef FE_INVALID
+	  if (__isinf (__real__ x))
+	    feraiseexcept (FE_INVALID);
+#endif
+	}
+    }
+  else
+    {
+      double sin2rx, cos2rx;
+      double den;
+
+      __sincos (2.0 * __real__ x, &sin2rx, &cos2rx);
+
+      den = cos2rx + __ieee754_cosh (2.0 * __imag__ x);
+
+      if (den == 0.0)
+	{
+	  __complex__ double ez = __cexp (1.0i * x);
+	  __complex__ double emz = __cexp (-1.0i * x);
+
+	  res = (ez - emz) / (ez + emz) * -1.0i;
+	}
+      else
+	{
+	  __real__ res = sin2rx / den;
+	  __imag__ res = __ieee754_sinh (2.0 * __imag__ x) / den;
+	}
+    }
+
+  return res;
+}
+weak_alias (__ctan, ctan)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__ctan, __ctanl)
+weak_alias (__ctan, ctanl)
+#endif