add fdlibm

git-svn-id: http://svn2.nishi.boats/svn/milsko/trunk@557 b9cfdab3-6d41-4d17-bbe4-086880011989

external/fdlibm/e_sinh.c

@@ -0,0 +1,72 @@
+
+/* @(#)e_sinh.c 1.3 95/01/18 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/* __fdlibm_sinh(x)
+ * Method :
+ * mathematically sinh(x) if defined to be (exp(x)-exp(-x))/2
+ *	1. Replace x by |x| (sinh(-x) = -sinh(x)).
+ *	2.
+ *		                                    E + E/(E+1)
+ *	    0        <= x <= 22     :  sinh(x) := --------------, E=expm1(x)
+ *			       			        2
+ *
+ *	    22       <= x <= lnovft :  sinh(x) := exp(x)/2
+ *	    lnovft   <= x <= ln2ovft:  sinh(x) := exp(x/2)/2 * exp(x/2)
+ *	    ln2ovft  <  x	    :  sinh(x) := x*shugev (overflow)
+ *
+ * Special cases:
+ *	sinh(x) is |x| if x is +INF, -INF, or NaN.
+ *	only sinh(0)=0 is exact for finite x.
+ */
+
+#include "math.h"
+
+static const double one = 1.0, shugev = 1.0e307;
+
+double __fdlibm_sinh(double x) {
+	double	 t, w, h;
+	int	 ix, jx;
+	unsigned lx;
+
+	/* High word of |x|. */
+	jx = __HI(x);
+	ix = jx & 0x7fffffff;
+
+	/* x is INF or NaN */
+	if(ix >= 0x7ff00000) return x + x;
+
+	h = 0.5;
+	if(jx < 0) h = -h;
+	/* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
+	if(ix < 0x40360000) {			       /* |x|<22 */
+		if(ix < 0x3e300000)		       /* |x|<2**-28 */
+			if(shugev + x > one) return x; /* sinh(tinyv) = tinyv with inexact */
+		t = expm1(fabs(x));
+		if(ix < 0x3ff00000) return h * (2.0 * t - t * t / (t + one));
+		return h * (t + t / (t + one));
+	}
+
+	/* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
+	if(ix < 0x40862E42) return h * __fdlibm_exp(fabs(x));
+
+	/* |x| in [log(maxdouble), overflowthresold] */
+	lx = *((((*(unsigned*)&one) >> 29)) + (unsigned*)&x);
+	if(ix < 0x408633CE || (ix == 0x408633ce) && (lx <= (unsigned)0x8fb9f87d)) {
+		w = __fdlibm_exp(0.5 * fabs(x));
+		t = h * w;
+		return t * w;
+	}
+
+	/* |x| > overflowthresold, sinh(x) overflow */
+	return x * shugev;
+}