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authorEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
committerEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
commit1077fa4d772832f77a677ce7fb7c2d513b959e3f (patch)
tree579bee13fb0b58d2800206366ec2caecbb15f3fc /libm/float/asinhf.c
parent22358dd7ce7bb49792204b698f01a6f69b9c8e08 (diff)
uClibc now has a math library. muahahahaha!
-Erik
Diffstat (limited to 'libm/float/asinhf.c')
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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 );
+}
+