1 files changed, 43 insertions, 0 deletions
diff --git a/src/math/atanhf.c b/src/math/atanhf.c
new file mode 100644
index 00000000..2efbd79c
--- /dev/null
+++ b/src/math/atanhf.c
@@ -0,0 +1,43 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/e_atanhf.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 "libm.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)  /* x < 2**-28 */
+		return x;
+	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;
+	return -t;
+}