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-rw-r--r--sysdeps/libm-ieee754/s_tanhf.c65
1 files changed, 65 insertions, 0 deletions
diff --git a/sysdeps/libm-ieee754/s_tanhf.c b/sysdeps/libm-ieee754/s_tanhf.c
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+++ b/sysdeps/libm-ieee754/s_tanhf.c
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+/* 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.
+ * ====================================================
+ */
+
+#if defined(LIBM_SCCS) && !defined(lint)
+static char rcsid[] = "$NetBSD: s_tanhf.c,v 1.4 1995/05/10 20:48:24 jtc Exp $";
+#endif
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const float one=1.0, two=2.0, tiny = 1.0e-30;
+#else
+static float one=1.0, two=2.0, tiny = 1.0e-30;
+#endif
+
+#ifdef __STDC__
+	float __tanhf(float x)
+#else
+	float __tanhf(x)
+	float x;
+#endif
+{
+	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| < 22 */
+	if (ix < 0x41b00000) {		/* |x|<22 */
+	    if (ix<0x24000000) 		/* |x|<2**-55 */
+		return x*(one+x);    	/* tanh(small) = small */
+	    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| > 22, return +-1 */
+	} else {
+	    z = one - tiny;		/* raised inexact flag */
+	}
+	return (jx>=0)? z: -z;
+}
+weak_alias (__tanhf, tanhf)