1 files changed, 59 insertions, 0 deletions
diff --git a/src/math/e_coshf.c b/src/math/e_coshf.c
new file mode 100644
index 00000000..6db10885
--- /dev/null
+++ b/src/math/e_coshf.c
@@ -0,0 +1,59 @@
+/* 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;
+}