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-rw-r--r--src/math/e_coshf.c59
1 files changed, 59 insertions, 0 deletions
diff --git a/src/math/e_coshf.c b/src/math/e_coshf.c
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+/* e_coshf.c -- float version of e_cosh.c.
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+#include <math.h>
+#include "math_private.h"
+
+static const float one = 1.0, half=0.5, huge = 1.0e30;
+
+float
+coshf(float x)
+{
+ float t,w;
+ int32_t ix;
+
+ GET_FLOAT_WORD(ix,x);
+ ix &= 0x7fffffff;
+
+ /* x is INF or NaN */
+ if(ix>=0x7f800000) return x*x;
+
+ /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
+ if(ix<0x3eb17218) {
+ t = expm1f(fabsf(x));
+ w = one+t;
+ if (ix<0x24000000) return w; /* cosh(tiny) = 1 */
+ return one+(t*t)/(w+w);
+ }
+
+ /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
+ if (ix < 0x41b00000) {
+ t = expf(fabsf(x));
+ return half*t+half/t;
+ }
+
+ /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
+ if (ix < 0x42b17180) return half*expf(fabsf(x));
+
+ /* |x| in [log(maxdouble), overflowthresold] */
+ if (ix<=0x42b2d4fc) {
+ w = expf(half*fabsf(x));
+ t = half*w;
+ return t*w;
+ }
+
+ /* |x| > overflowthresold, cosh(x) overflow */
+ return huge*huge;
+}