1 files changed, 67 insertions, 0 deletions
diff --git a/libm/float/coshf.c b/libm/float/coshf.c
new file mode 100644
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+/*							coshf.c
+ *
+ *	Hyperbolic cosine
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * float x, y, coshf();
+ *
+ * y = coshf( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns hyperbolic cosine of argument in the range MINLOGF to
+ * MAXLOGF.
+ *
+ * cosh(x)  =  ( exp(x) + exp(-x) )/2.
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Relative error:
+ * arithmetic   domain     # trials      peak         rms
+ *    IEEE     +-MAXLOGF    100000      1.2e-7      2.8e-8
+ *
+ *
+ * ERROR MESSAGES:
+ *
+ *   message         condition      value returned
+ * coshf overflow  |x| > MAXLOGF       MAXNUMF
+ *
+ *
+ */
+
+/*							cosh.c */
+
+/*
+Cephes Math Library Release 2.2:  June, 1992
+Copyright 1985, 1987, 1992 by Stephen L. Moshier
+Direct inquiries to 30 Frost Street, Cambridge, MA 02140
+*/
+
+#include <math.h>
+extern float MAXLOGF, MAXNUMF;
+
+float expf(float);
+
+float coshf(float xx)
+{
+float x, y;
+
+x = xx;
+if( x < 0 )
+	x = -x;
+if( x > MAXLOGF )
+	{
+	mtherr( "coshf", OVERFLOW );
+	return( MAXNUMF );
+	}	
+y = expf(x);
+y = y + 1.0/y;
+return( 0.5*y );
+}