1 files changed, 165 insertions, 0 deletions
diff --git a/libm/double/asinh.c b/libm/double/asinh.c
new file mode 100644
index 000000000..57966d264
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+++ b/libm/double/asinh.c
@@ -0,0 +1,165 @@
+/*							asinh.c
+ *
+ *	Inverse hyperbolic sine
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double x, y, asinh();
+ *
+ * y = asinh( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns inverse hyperbolic sine of argument.
+ *
+ * If |x| < 0.5, the function is approximated by a rational
+ * form  x + x**3 P(x)/Q(x).  Otherwise,
+ *
+ *     asinh(x) = log( x + sqrt(1 + x*x) ).
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Relative error:
+ * arithmetic   domain     # trials      peak         rms
+ *    DEC      -3,3         75000       4.6e-17     1.1e-17
+ *    IEEE     -1,1         30000       3.7e-16     7.8e-17
+ *    IEEE      1,3         30000       2.5e-16     6.7e-17
+ *
+ */
+
+/*						asinh.c	*/
+
+/*
+Cephes Math Library Release 2.8:  June, 2000
+Copyright 1984, 1995, 2000 by Stephen L. Moshier
+*/
+
+
+#include <math.h>
+
+#ifdef UNK
+static double P[] = {
+-4.33231683752342103572E-3,
+-5.91750212056387121207E-1,
+-4.37390226194356683570E0,
+-9.09030533308377316566E0,
+-5.56682227230859640450E0
+};
+static double Q[] = {
+/* 1.00000000000000000000E0,*/
+ 1.28757002067426453537E1,
+ 4.86042483805291788324E1,
+ 6.95722521337257608734E1,
+ 3.34009336338516356383E1
+};
+#endif
+
+#ifdef DEC
+static unsigned short P[] = {
+0136215,0173033,0110410,0105475,
+0140027,0076361,0020056,0164520,
+0140613,0173401,0160136,0053142,
+0141021,0070744,0000503,0176261,
+0140662,0021550,0073106,0133351
+};
+static unsigned short Q[] = {
+/* 0040200,0000000,0000000,0000000,*/
+0041116,0001336,0034120,0173054,
+0041502,0065300,0013144,0021231,
+0041613,0022376,0035516,0153063,
+0041405,0115216,0054265,0004557
+};
+#endif
+
+#ifdef IBMPC
+static unsigned short P[] = {
+0x1168,0x7221,0xbec3,0xbf71,
+0xdd2a,0x2405,0xef9e,0xbfe2,
+0xcacc,0x3c0b,0x7ee0,0xc011,
+0x7f96,0x8028,0x2e3c,0xc022,
+0xd6dd,0x0ec8,0x446d,0xc016
+};
+static unsigned short Q[] = {
+/* 0x0000,0x0000,0x0000,0x3ff0,*/
+0x1ec5,0xc70a,0xc05b,0x4029,
+0x8453,0x02cc,0x4d58,0x4048,
+0xdac6,0xc769,0x649f,0x4051,
+0xa12e,0xcb16,0xb351,0x4040
+};
+#endif
+
+#ifdef MIEEE
+static unsigned short P[] = {
+0xbf71,0xbec3,0x7221,0x1168,
+0xbfe2,0xef9e,0x2405,0xdd2a,
+0xc011,0x7ee0,0x3c0b,0xcacc,
+0xc022,0x2e3c,0x8028,0x7f96,
+0xc016,0x446d,0x0ec8,0xd6dd
+};
+static unsigned short Q[] = {
+0x4029,0xc05b,0xc70a,0x1ec5,
+0x4048,0x4d58,0x02cc,0x8453,
+0x4051,0x649f,0xc769,0xdac6,
+0x4040,0xb351,0xcb16,0xa12e
+};
+#endif
+
+#ifdef ANSIPROT
+extern double polevl ( double, void *, int );
+extern double p1evl ( double, void *, int );
+extern double sqrt ( double );
+extern double log ( double );
+#else
+double log(), sqrt(), polevl(), p1evl();
+#endif
+extern double LOGE2, INFINITY;
+
+double asinh(xx)
+double xx;
+{
+double a, z, x;
+int sign;
+
+#ifdef MINUSZERO
+if( xx == 0.0 )
+  return(xx);
+#endif
+if( xx < 0.0 )
+	{
+	sign = -1;
+	x = -xx;
+	}
+else
+	{
+	sign = 1;
+	x = xx;
+	}
+
+if( x > 1.0e8 )
+	{
+#ifdef INFINITIES
+	  if( x == INFINITY )
+	    return(xx);
+#endif
+	return( sign * (log(x) + LOGE2) );
+	}
+
+z = x * x;
+if( x < 0.5 )
+	{
+	a = ( polevl(z, P, 4)/p1evl(z, Q, 4) ) * z;
+	a = a * x  +  x;
+	if( sign < 0 )
+		a = -a;
+	return(a);
+	}	
+
+a = sqrt( z + 1.0 );
+return( sign * log(x + a) );
+}