Improve clog, clog10 handling of values with real or imaginary part slightly above 1 (bug 13629).

1 files changed, 7 insertions, 0 deletions

diff --git a/math/s_clog.c b/math/s_clog.c
index e28aa5157d..2593066001 100644
--- a/math/s_clog.c
+++ b/math/s_clog.c
@@ -78,6 +78,13 @@ __clog (__complex__ double x)
 	  else
 	    __real__ result = __log1p (absy2) / 2.0;
 	}
+      else if (absx > 1.0 && absx < 2.0 && absy < 1.0 && scale == 0)
+	{
+	  double d2m1 = (absx - 1.0) * (absx + 1.0);
+	  if (absy >= DBL_EPSILON)
+	    d2m1 += absy * absy;
+	  __real__ result = __log1p (d2m1) / 2.0;
+	}
       else
 	{
 	  double d = __ieee754_hypot (absx, absy);