1 files changed, 42 insertions, 0 deletions
diff --git a/src/math/e_atanhf.c b/src/math/e_atanhf.c
new file mode 100644
index 00000000..7356cfc9
--- /dev/null
+++ b/src/math/e_atanhf.c
@@ -0,0 +1,42 @@
+/* e_atanhf.c -- float version of e_atanh.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.
+ * ====================================================
+ */
+
+#include <math.h>
+#include "math_private.h"
+
+static const float one = 1.0, huge = 1e30;
+
+static const float zero = 0.0;
+
+float
+atanhf(float x)
+{
+        float t;
+        int32_t hx,ix;
+        GET_FLOAT_WORD(hx,x);
+        ix = hx&0x7fffffff;
+        if (ix>0x3f800000)              /* |x|>1 */
+            return (x-x)/(x-x);
+        if(ix==0x3f800000)
+            return x/zero;
+        if(ix<0x31800000&&(huge+x)>zero) return x;      /* x<2**-28 */
+        SET_FLOAT_WORD(x,ix);
+        if(ix<0x3f000000) {             /* x < 0.5 */
+            t = x+x;
+            t = (float)0.5*log1pf(t+t*x/(one-x));
+        } else
+            t = (float)0.5*log1pf((x+x)/(one-x));
+        if(hx>=0) return t; else return -t;
+}