1 files changed, 98 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/ieee754/dbl-64/s_tanh.c b/REORG.TODO/sysdeps/ieee754/dbl-64/s_tanh.c
new file mode 100644
index 0000000000..344a2f0330
--- /dev/null
+++ b/REORG.TODO/sysdeps/ieee754/dbl-64/s_tanh.c
@@ -0,0 +1,98 @@
+/* @(#)s_tanh.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * 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_tanh.c,v 1.7 1995/05/10 20:48:22 jtc Exp $";
+#endif
+
+/* Tanh(x)
+ * Return the Hyperbolic Tangent of x
+ *
+ * Method :
+ *				       x    -x
+ *				      e  - e
+ *	0. tanh(x) is defined to be -----------
+ *				       x    -x
+ *				      e  + e
+ *	1. reduce x to non-negative by tanh(-x) = -tanh(x).
+ *	2.  0      <= x <= 2**-55 : tanh(x) := x*(one+x)
+ *					        -t
+ *	    2**-55 <  x <=  1     : tanh(x) := -----; t = expm1(-2x)
+ *					       t + 2
+ *						     2
+ *	    1      <= x <=  22.0  : tanh(x) := 1-  ----- ; t=expm1(2x)
+ *						   t + 2
+ *	    22.0   <  x <= INF    : tanh(x) := 1.
+ *
+ * Special cases:
+ *	tanh(NaN) is NaN;
+ *	only tanh(0)=0 is exact for finite argument.
+ */
+
+#include <float.h>
+#include <math.h>
+#include <math_private.h>
+
+static const double one = 1.0, two = 2.0, tiny = 1.0e-300;
+
+double
+__tanh (double x)
+{
+  double t, z;
+  int32_t jx, ix, lx;
+
+  /* High word of |x|. */
+  EXTRACT_WORDS (jx, lx, x);
+  ix = jx & 0x7fffffff;
+
+  /* x is INF or NaN */
+  if (ix >= 0x7ff00000)
+    {
+      if (jx >= 0)
+	return one / x + one;               /* tanh(+-inf)=+-1 */
+      else
+	return one / x - one;               /* tanh(NaN) = NaN */
+    }
+
+  /* |x| < 22 */
+  if (ix < 0x40360000)                  /* |x|<22 */
+    {
+      if ((ix | lx) == 0)
+	return x;                       /* x == +-0 */
+      if (ix < 0x3c800000)              /* |x|<2**-55 */
+	{
+	  math_check_force_underflow (x);
+	  return x * (one + x);           /* tanh(small) = small */
+	}
+      if (ix >= 0x3ff00000)             /* |x|>=1  */
+	{
+	  t = __expm1 (two * fabs (x));
+	  z = one - two / (t + two);
+	}
+      else
+	{
+	  t = __expm1 (-two * fabs (x));
+	  z = -t / (t + two);
+	}
+      /* |x| > 22, return +-1 */
+    }
+  else
+    {
+      z = one - tiny;                   /* raised inexact flag */
+    }
+  return (jx >= 0) ? z : -z;
+}
+weak_alias (__tanh, tanh)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__tanh, __tanhl)
+weak_alias (__tanh, tanhl)
+#endif