1 files changed, 56 insertions, 0 deletions
diff --git a/libm/src/s_tanhf.c b/libm/src/s_tanhf.c
new file mode 100644
index 0000000..0aca6cc
--- /dev/null
+++ b/libm/src/s_tanhf.c
@@ -0,0 +1,56 @@
+/* s_tanhf.c -- float version of s_tanh.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.
+ * ====================================================
+ */
+
+#ifndef lint
+static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_tanhf.c,v 1.8 2005/12/11 11:40:55 bde Exp $";
+#endif
+
+#include "math.h"
+#include "math_private.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 */
+	}
+
+    /* |x| < 9 */
+	if (ix < 0x41100000) {		/* |x|<9 */
+	    if (ix<0x39800000) {	/* |x|<2**-12 */
+		if(huge+x>one) return x; /* tanh(tiny) = tiny with inexact */
+	    }
+	    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);
+	    }
+    /* |x| >= 9, return +-1 */
+	} else {
+	    z = one - tiny;		/* raise inexact flag */
+	}
+	return (jx>=0)? z: -z;
+}