1 files changed, 66 insertions, 0 deletions
diff --git a/libquadmath/math/atanhq.c b/libquadmath/math/atanhq.c
new file mode 100644
index 000000000..73db957d3
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+++ b/libquadmath/math/atanhq.c
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+/* s_atanhl.c -- __float128 version of s_atan.c.
+ * Conversion to __float128 by Ulrich Drepper,
+ * Cygnus Support, drepper@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.
+ * ====================================================
+ */
+
+/* __ieee754_atanhl(x)
+ * Method :
+ *    1.Reduced x to positive by atanh(-x) = -atanh(x)
+ *    2.For x>=0.5
+ *                   1              2x                          x
+ *	atanhl(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------)
+ *                   2             1 - x                      1 - x
+ *
+ * 	For x<0.5
+ *	atanhl(x) = 0.5*log1pl(2x+2x*x/(1-x))
+ *
+ * Special cases:
+ *	atanhl(x) is NaN if |x| > 1 with signal;
+ *	atanhl(NaN) is that NaN with no signal;
+ *	atanhl(+-1) is +-INF with signal.
+ *
+ */
+
+#include "quadmath-imp.h"
+
+static const __float128 one = 1.0Q, huge = 1e4900Q;
+static const __float128 zero = 0.0Q;
+
+__float128
+atanhq (__float128 x)
+{
+	__float128 t;
+	uint32_t jx, ix;
+	ieee854_float128 u;
+
+	u.value = x;
+	jx = u.words32.w0;
+	ix = jx & 0x7fffffff;
+	u.words32.w0 = ix;
+	if (ix >= 0x3fff0000) /* |x| >= 1.0 or infinity or NaN */
+	  {
+	    if (u.value == one)
+	      return x/zero;
+	    else
+	      return (x-x)/(x-x);
+	  }
+	if(ix<0x3fc60000 && (huge+x)>zero) return x;	/* x < 2^-57 */
+
+	if(ix<0x3ffe0000) {		/* x < 0.5 */
+	    t = u.value+u.value;
+	    t = 0.5*log1pq(t+t*u.value/(one-u.value));
+	} else
+	    t = 0.5*log1pq((u.value+u.value)/(one-u.value));
+	if(jx & 0x80000000) return -t; else return t;
+}