1 files changed, 57 insertions, 0 deletions
diff --git a/src/math/coshf.c b/src/math/coshf.c
new file mode 100644
index 00000000..9e87afcd
--- /dev/null
+++ b/src/math/coshf.c
@@ -0,0 +1,57 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/e_coshf.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 "libm.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<0x39800000)
+			return one;  /* cosh(tiny) = 1 */
+		return one + (t*t)/(w+w);
+	}
+
+	/* |x| in [0.5*ln2,9], return (exp(|x|)+1/exp(|x|))/2; */
+	if (ix < 0x41100000) {
+		t = expf(fabsf(x));
+		return half*t + half/t;
+	}
+
+	/* |x| in [9, log(maxfloat)] return half*exp(|x|) */
+	if (ix < 0x42b17217)
+		return half*expf(fabsf(x));
+
+	/* |x| in [log(maxfloat), overflowthresold] */
+	if (ix <= 0x42b2d4fc)
+		return __expo2f(fabsf(x));
+
+	/* |x| > overflowthresold, cosh(x) overflow */
+	return huge*huge;
+}