* include/math.h (ashinh, asinhf, asinhl, acosh, acoshf, acoshl,

	atanh, atanhf, atanhl): Add prototypes.
	* mingwex/Makefile.in (MATH_OBJS): Add objects for above to list.
	(MATH_DISTFILES): Add sources for above and fastmath.h to list.
	Specify dependency on fastmath.h for new objects.
	* mingwex/math/fastmath.h: New file.
	* mingwex/math/ashinh.c: New file.
	* mingwex/math/asinhf.c: New file.
	* mingwex/math/asinhl.c: New file.
	* mingwex/math/acosh.c: New file.
	* mingwex/math/acoshf.c: New file.
	* mingwex/math/acoshl.c: New file.
	* mingwex/math/atanh.c: New file.
	* mingwex/math/atanhf.c: New file.
	* mingwex/math/atanhl.c: New file.

1 files changed, 30 insertions, 0 deletions

diff --git a/winsup/mingw/mingwex/math/atanhf.c b/winsup/mingw/mingwex/math/atanhf.c
new file mode 100755
index 000000000..b7c30823e
--- /dev/null
+++ b/winsup/mingw/mingwex/math/atanhf.c
@@ -0,0 +1,30 @@
+#include <math.h>
+#include <errno.h>
+#include "fastmath.h"
+
+/* atanh (x) = 0.5 * log ((1.0 + x)/(1.0 - x)) */
+float atanhf (float x)
+{
+  float z;
+  if isnan (x)
+    return x;
+  z = fabsf (x);
+  if (z == 1.0)
+    {
+      errno  = ERANGE;
+      return (x > 0 ? INFINITY : -INFINITY);
+    }
+  if ( z > 1.0)
+    {
+      errno = EDOM;
+      return nanf("");
+    }
+  /* Rearrange formula to avoid precision loss for small x.
+
+  atanh(x) = 0.5 * log ((1.0 + x)/(1.0 - x))
+	   = 0.5 * log1p ((1.0 + x)/(1.0 - x) - 1.0)
+           = 0.5 * log1p ((1.0 + x - 1.0 + x) /(1.0 - x)) 
+           = 0.5 * log1p ((2.0 * x ) / (1.0 - x))  */
+  z = 0.5 * __fast_log1p ((z + z) / (1.0 - z));
+  return x >= 0 ? z : -z;
+}