Prepare to convert _Complex tangent functions

This patch has no function changes, except to
ensure the git history correctly tracks the
changes to convert the double version of these
functions into a templated version.

1 files changed, 129 insertions, 0 deletions

diff --git a/math/s_ctan_template.c b/math/s_ctan_template.c
new file mode 100644
index 0000000..8e8bf2e
--- /dev/null
+++ b/math/s_ctan_template.c
@@ -0,0 +1,129 @@
+/* Complex tangent function for double.
+   Copyright (C) 1997-2016 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, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <complex.h>
+#include <fenv.h>
+#include <math.h>
+#include <math_private.h>
+#include <float.h>
+
+__complex__ double
+__ctan (__complex__ double x)
+{
+  __complex__ double res;
+
+  if (__glibc_unlikely (!isfinite (__real__ x) || !isfinite (__imag__ x)))
+    {
+      if (isinf (__imag__ x))
+	{
+	  if (isfinite (__real__ x) && fabs (__real__ x) > 1.0)
+	    {
+	      double sinrx, cosrx;
+	      __sincos (__real__ x, &sinrx, &cosrx);
+	      __real__ res = __copysign (0.0, sinrx * cosrx);
+	    }
+	  else
+	    __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 ("");
+
+	  if (isinf (__real__ x))
+	    feraiseexcept (FE_INVALID);
+	}
+    }
+  else
+    {
+      double sinrx, cosrx;
+      double den;
+      const int t = (int) ((DBL_MAX_EXP - 1) * M_LN2 / 2);
+
+      /* tan(x+iy) = (sin(2x) + i*sinh(2y))/(cos(2x) + cosh(2y))
+	 = (sin(x)*cos(x) + i*sinh(y)*cosh(y)/(cos(x)^2 + sinh(y)^2). */
+
+      if (__glibc_likely (fabs (__real__ x) > DBL_MIN))
+	{
+	  __sincos (__real__ x, &sinrx, &cosrx);
+	}
+      else
+	{
+	  sinrx = __real__ x;
+	  cosrx = 1.0;
+	}
+
+      if (fabs (__imag__ x) > t)
+	{
+	  /* Avoid intermediate overflow when the real part of the
+	     result may be subnormal.  Ignoring negligible terms, the
+	     imaginary part is +/- 1, the real part is
+	     sin(x)*cos(x)/sinh(y)^2 = 4*sin(x)*cos(x)/exp(2y).  */
+	  double exp_2t = __ieee754_exp (2 * t);
+
+	  __imag__ res = __copysign (1.0, __imag__ x);
+	  __real__ res = 4 * sinrx * cosrx;
+	  __imag__ x = fabs (__imag__ x);
+	  __imag__ x -= t;
+	  __real__ res /= exp_2t;
+	  if (__imag__ x > t)
+	    {
+	      /* Underflow (original imaginary part of x has absolute
+		 value > 2t).  */
+	      __real__ res /= exp_2t;
+	    }
+	  else
+	    __real__ res /= __ieee754_exp (2 * __imag__ x);
+	}
+      else
+	{
+	  double sinhix, coshix;
+	  if (fabs (__imag__ x) > DBL_MIN)
+	    {
+	      sinhix = __ieee754_sinh (__imag__ x);
+	      coshix = __ieee754_cosh (__imag__ x);
+	    }
+	  else
+	    {
+	      sinhix = __imag__ x;
+	      coshix = 1.0;
+	    }
+
+	  if (fabs (sinhix) > fabs (cosrx) * DBL_EPSILON)
+	    den = cosrx * cosrx + sinhix * sinhix;
+	  else
+	    den = cosrx * cosrx;
+	  __real__ res = sinrx * cosrx / den;
+	  __imag__ res = sinhix * coshix / den;
+	}
+      math_check_force_underflow_complex (res);
+    }
+
+  return res;
+}
+weak_alias (__ctan, ctan)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__ctan, __ctanl)
+weak_alias (__ctan, ctanl)
+#endif