1 files changed, 77 insertions, 0 deletions
diff --git a/newlib/libm/mathfp/sf_tanh.c b/newlib/libm/mathfp/sf_tanh.c
new file mode 100644
index 000000000..51806af45
--- /dev/null
+++ b/newlib/libm/mathfp/sf_tanh.c
@@ -0,0 +1,77 @@
+
+/* @(#)z_tanhf.c 1.0 98/08/13 */
+/*****************************************************************
+ * The following routines are coded directly from the algorithms
+ * and coefficients given in "Software Manual for the Elementary
+ * Functions" by William J. Cody, Jr. and William Waite, Prentice
+ * Hall, 1980.
+ *****************************************************************/
+/******************************************************************
+ * Hyperbolic Tangent
+ *
+ * Input:
+ *   x - floating point value
+ *
+ * Output:
+ *   hyperbolic tangent of x
+ *
+ * Description:
+ *   This routine calculates hyperbolic tangent.
+ *
+ *****************************************************************/
+
+#include <float.h>
+#include "fdlibm.h"
+#include "zmath.h"
+
+static const float LN3_OVER2 = 0.5493061443;
+static const float p[] = { -0.2059432032,
+                           -0.0009577527 };
+static const float q[] = {  0.6178299136,
+                            0.25 };
+
+float
+_DEFUN (tanhf, (float),
+        float x)
+{
+  float f, res, g, P, Q, R;
+
+  f = fabsf (x);
+
+  /* Check if the input is too big. */ 
+  if (f > BIGX)
+    res = 1.0; 
+
+  else if (f > LN3_OVER2)
+    res = 1.0 - 2.0 / (exp (2 * f) + 1.0);
+
+  /* Check if the input is too small. */
+  else if (f < z_rooteps_f)
+    res = f;
+
+  /* Calculate the Taylor series. */
+  else
+    {
+      g = f * f;
+
+      P = p[1] * g + p[0];
+      Q = (g + q[1]) * g + q[0];
+      R = g * (P / Q);
+
+      res = f + f * R;
+    }
+
+  if (x < 0.0)
+    res = -res;
+
+  return (res);
+}
+
+#ifdef _DOUBLE_IS_32BITS
+
+double tanh (double x)
+{
+  return (double) tanhf ((float) x);
+}
+
+#endif _DOUBLE_IS_32BITS