complex: fix ctanh(+-0+i*nan) and ctanh(+-0+-i*inf)

[oweals/musl.git] / src / complex / ctanh.c

diff --git a/src/complex/ctanh.c b/src/complex/ctanh.c
index 0461050d73301adfad8e5571316d96b07556449a..3ba3a8997d80349099e4b9b98fcac27fae1f828d 100644 (file)
--- a/src/complex/ctanh.c
+++ b/src/complex/ctanh.c
@@ -101,11 +101,13 @@ double complex ctanh(double complex z)
        }
 
        /*
+        * ctanh(+-0 + i NAN) = +-0 + i NaN
+        * ctanh(+-0 +- i Inf) = +-0 + i NaN
         * ctanh(x + i NAN) = NaN + i NaN
         * ctanh(x +- i Inf) = NaN + i NaN
         */
        if (!isfinite(y))
-               return CMPLX(y - y, y - y);
+               return CMPLX(x ? y - y : x, y - y);
 
        /*
         * ctanh(+-huge + i +-y) ~= +-1 +- i 2sin(2y)/exp(2x), using the