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[thirdparty/glibc.git] / math / s_ctan.c

diff --git a/math/s_ctan.c b/math/s_ctan.c
index 78117b31031d81ba672683cb60bcfb78e8953908..6fed4fe465487b1e363302ec58ce9d680da2247a 100644 (file)
--- a/math/s_ctan.c
+++ b/math/s_ctan.c
@@ -1,5 +1,5 @@
 /* Complex tangent function for double.
-   Copyright (C) 1997-2012 Free Software Foundation, Inc.
+   Copyright (C) 1997-2014 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
 
@@ -53,11 +53,20 @@ __ctan (__complex__ double x)
       double sinrx, cosrx;
       double den;
       const int t = (int) ((DBL_MAX_EXP - 1) * M_LN2 / 2);
+      int rcls = fpclassify (__real__ x);
 
       /* 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). */
 
-      __sincos (__real__ x, &sinrx, &cosrx);
+      if (__builtin_expect (rcls != FP_SUBNORMAL, 1))
+       {
+         __sincos (__real__ x, &sinrx, &cosrx);
+       }
+      else
+       {
+         sinrx = __real__ x;
+         cosrx = 1.0;
+       }
 
       if (fabs (__imag__ x) > t)
        {
@@ -83,10 +92,22 @@ __ctan (__complex__ double x)
        }
       else
        {
-         double sinhix = __ieee754_sinh (__imag__ x);
-         double coshix = __ieee754_cosh (__imag__ x);
+         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;
+           }
 
-         den = cosrx * cosrx + sinhix * sinhix;
+         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;
        }