1 files changed, 65 insertions, 0 deletions
diff --git a/libm/s_asinh.c b/libm/s_asinh.c
new file mode 100644
index 000000000..6cad188ca
--- /dev/null
+++ b/libm/s_asinh.c
@@ -0,0 +1,65 @@
+/* @(#)s_asinh.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+#if defined(LIBM_SCCS) && !defined(lint)
+static char rcsid[] = "$NetBSD: s_asinh.c,v 1.9 1995/05/12 04:57:37 jtc Exp $";
+#endif
+
+/* asinh(x)
+ * Method :
+ *	Based on 
+ *		asinh(x) = sign(x) * log [ |x| + sqrt(x*x+1) ]
+ *	we have
+ *	asinh(x) := x  if  1+x*x=1,
+ *		 := sign(x)*(log(x)+ln2)) for large |x|, else
+ *		 := sign(x)*log(2|x|+1/(|x|+sqrt(x*x+1))) if|x|>2, else
+ *		 := sign(x)*log1p(|x| + x^2/(1 + sqrt(1+x^2)))  
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const double 
+#else
+static double 
+#endif
+one =  1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */
+ln2 =  6.93147180559945286227e-01, /* 0x3FE62E42, 0xFEFA39EF */
+huge=  1.00000000000000000000e+300; 
+
+#ifdef __STDC__
+	double asinh(double x)
+#else
+	double asinh(x)
+	double x;
+#endif
+{	
+	double t,w;
+	int32_t hx,ix;
+	GET_HIGH_WORD(hx,x);
+	ix = hx&0x7fffffff;
+	if(ix>=0x7ff00000) return x+x;	/* x is inf or NaN */
+	if(ix< 0x3e300000) {	/* |x|<2**-28 */
+	    if(huge+x>one) return x;	/* return x inexact except 0 */
+	} 
+	if(ix>0x41b00000) {	/* |x| > 2**28 */
+	    w = __ieee754_log(fabs(x))+ln2;
+	} else if (ix>0x40000000) {	/* 2**28 > |x| > 2.0 */
+	    t = fabs(x);
+	    w = __ieee754_log(2.0*t+one/(__ieee754_sqrt(x*x+one)+t));
+	} else {		/* 2.0 > |x| > 2**-28 */
+	    t = x*x;
+	    w =log1p(fabs(x)+t/(one+__ieee754_sqrt(one+t)));
+	}
+	if(hx>0) return w; else return -w;
+}