1 files changed, 53 insertions, 0 deletions
diff --git a/src/math/tanhf.c b/src/math/tanhf.c
new file mode 100644
index 00000000..97d0eb53
--- /dev/null
+++ b/src/math/tanhf.c
@@ -0,0 +1,53 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_tanhf.c */
+/*
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#include "libm.h"
+
+static const float one = 1.0, two = 2.0, tiny = 1.0e-30, huge = 1.0e30;
+
+float tanhf(float x)
+{
+	float t,z;
+	int32_t jx,ix;
+
+	GET_FLOAT_WORD(jx, x);
+	ix = jx & 0x7fffffff;
+
+	/* x is INF or NaN */
+	if(ix >= 0x7f800000) {
+		if (jx >= 0)
+			return one/x + one;  /* tanh(+-inf)=+-1 */
+		else
+			return one/x - one;  /* tanh(NaN) = NaN */
+	}
+
+	if (ix < 0x41100000) {  /* |x| < 9 */
+		if (ix < 0x39800000) {  /* |x| < 2**-12 */
+			/* tanh(tiny) = tiny with inexact */
+			if (huge+x > one)
+				return x;
+		}
+		if (ix >= 0x3f800000) {  /* |x|>=1  */
+			t = expm1f(two*fabsf(x));
+			z = one - two/(t+two);
+		} else {
+			t = expm1f(-two*fabsf(x));
+			z = -t/(t+two);
+		}
+	} else {  /* |x| >= 9, return +-1 */
+		z = one - tiny;  /* raise inexact */
+	}
+	return jx >= 0 ? z : -z;
+}