1 files changed, 88 insertions, 0 deletions
diff --git a/libm/float/asinhf.c b/libm/float/asinhf.c
new file mode 100644
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+/*							asinhf.c
+ *
+ *	Inverse hyperbolic sine
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * float x, y, asinhf();
+ *
+ * y = asinhf( 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
+ *    IEEE     -3,3        100000       2.4e-7      4.1e-8
+ *
+ */
+
+/*						asinh.c	*/
+
+/*
+Cephes Math Library Release 2.2:  June, 1992
+Copyright 1984, 1987, 1988, 1992 by Stephen L. Moshier
+Direct inquiries to 30 Frost Street, Cambridge, MA 02140
+*/
+
+/* Single precision inverse hyperbolic sine
+ * test interval: [-0.5, +0.5]
+ * trials: 10000
+ * peak relative error: 8.8e-8
+ * rms relative error: 3.2e-8
+ */
+#include <math.h>
+extern float LOGE2F;
+
+float logf( float );
+float sqrtf( float );
+
+float asinhf( float xx )
+{
+float x, z;
+
+if( xx < 0 )
+	x = -xx;
+else
+	x = xx;
+
+if( x > 1500.0 )
+	{
+	z = logf(x) + LOGE2F;
+	goto done;
+	}
+z = x * x;
+if( x < 0.5 )
+	{
+	z =
+	((( 2.0122003309E-2 * z
+	  - 4.2699340972E-2) * z
+	  + 7.4847586088E-2) * z
+	  - 1.6666288134E-1) * z * x
+	  + x;
+	}
+else
+	{
+	z = sqrtf( z + 1.0 );
+	z = logf( x + z );
+	}
+done:
+if( xx < 0 )
+	z = -z;
+return( z );
+}
+