Fix wrong ussage of sincos for subnormal arguments

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

diff --git a/math/s_ctanh.c b/math/s_ctanh.c
index d288b7d168f24818683b70747a31f7811d8703f6..fee19105512eeddfe284a7a5e9dadf0d56475578 100644 (file)
--- a/math/s_ctanh.c
+++ b/math/s_ctanh.c
@@ -53,11 +53,20 @@ __ctanh (__complex__ double x)
       double sinix, cosix;
       double den;
       const int t = (int) ((DBL_MAX_EXP - 1) * M_LN2 / 2);
+      int icls = fpclassify (__imag__ x);
 
       /* tanh(x+iy) = (sinh(2x) + i*sin(2y))/(cosh(2x) + cos(2y))
         = (sinh(x)*cosh(x) + i*sin(y)*cos(y))/(sinh(x)^2 + cos(y)^2).  */
 
-      __sincos (__imag__ x, &sinix, &cosix);
+      if (__builtin_expect (icls != FP_SUBNORMAL, 1))
+       {
+         __sincos (__imag__ x, &sinix, &cosix);
+       }
+      else
+       {
+         sinix = __imag__ x;
+         cosix = 1.0;
+       }
 
       if (fabs (__real__ x) > t)
        {