Fix a corner case: tan(large + Inf i) == NaN + NaN i.

2 files changed, 10 insertions, 0 deletions

diff --git a/lib/msun/src/s_ctanh.c b/lib/msun/src/s_ctanh.c
index 1705e90..d427e28 100644
--- a/lib/msun/src/s_ctanh.c
+++ b/lib/msun/src/s_ctanh.c
@@ -108,6 +108,13 @@ ctanh(double complex z)
 	}
 
 	/*
+	 * ctanh(x + i NAN) = NaN + i NaN
+	 * ctanh(x +- i Inf) = NaN + i NaN
+	 */
+	if (!isfinite(y))
+		return (cpack(y - y, y - y));
+
+	/*
 	 * ctanh(+-huge + i +-y) ~= +-1 +- i 2sin(2y)/exp(2x), using the
 	 * approximation sinh^2(huge) ~= exp(2*huge) / 4.
 	 * We use a modified formula to avoid spurious overflow.
diff --git a/lib/msun/src/s_ctanhf.c b/lib/msun/src/s_ctanhf.c
index ae833df..4be28d8 100644
--- a/lib/msun/src/s_ctanhf.c
+++ b/lib/msun/src/s_ctanhf.c
@@ -57,6 +57,9 @@ ctanhf(float complex z)
 		    copysignf(0, isinf(y) ? y : sinf(y) * cosf(y))));
 	}
 
+	if (!isfinite(y))
+		return (cpackf(y - y, y - y));
+
 	if (ix >= 0x41300000) {	/* x >= 11 */
 		float exp_mx = expf(-fabsf(x));
 		return (cpackf(copysignf(1, x),