Initial revision

2005-04-21 14:53:53 +00:00
commit 9865aeaa79
2264 changed files with 411685 additions and 0 deletions
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+/*
+ * (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
+ * See the copyright notice in the ACK home directory, in the file "Copyright".
+ *
+ * Author: Ceriel J.H. Jacobs
+ */
+
+/* $Header$ */
+#define __NO_DEFS
+#include <math.h>
+#include <pc_err.h>
+extern	_trp();
+
+#if __STDC__
+#include <float.h>
+#include <pc_math.h>
+#define M_MIN_D	DBL_MIN
+#define M_MAX_D	DBL_MAX
+#define M_DMINEXP DBL_MIN_EXP
+#endif
+#undef HUGE
+#define HUGE	1e1000
+
+static double
+Ldexp(fl,exp)
+	double fl;
+	int exp;
+{
+	extern double _fef();
+	int sign = 1;
+	int currexp;
+
+	if (fl<0) {
+		fl = -fl;
+		sign = -1;
+	}
+	fl = _fef(fl,&currexp);
+	exp += currexp;
+	if (exp > 0) {
+		while (exp>30) {
+			fl *= (double) (1L << 30);
+			exp -= 30;
+		}
+		fl *= (double) (1L << exp);
+	}
+	else	{
+		while (exp<-30) {
+			fl /= (double) (1L << 30);
+			exp += 30;
+		}
+		fl /= (double) (1L << -exp);
+	}
+	return sign * fl;
+}
+
+double
+_exp(x)
+	double x;
+{
+	/*	Algorithm and coefficients from:
+			"Software manual for the elementary functions"
+			by W.J. Cody and W. Waite, Prentice-Hall, 1980
+	*/
+
+	static double p[] = {
+	        0.25000000000000000000e+0,
+	        0.75753180159422776666e-2,
+		0.31555192765684646356e-4
+	};
+
+	static double q[] = {
+	        0.50000000000000000000e+0,
+	        0.56817302698551221787e-1,
+	        0.63121894374398503557e-3,
+		0.75104028399870046114e-6
+	};
+	double	xn, g;
+	int	n;
+	int	negative = x < 0;
+
+	if (x <= M_LN_MIN_D) {
+		g = M_MIN_D/4.0;
+
+		if (g != 0.0) {
+			/* unnormalized numbers apparently exist */
+			if (x < (M_LN2 * (M_DMINEXP - 53))) return 0.0;
+		}
+		else {
+			if (x < M_LN_MIN_D) return 0.0;
+			return M_MIN_D;
+		}
+	}
+	if (x >= M_LN_MAX_D) {
+		if (x > M_LN_MAX_D) {
+			_trp(EEXP);
+			return HUGE;
+		}
+		return M_MAX_D;
+	}
+	if (negative) x = -x;
+
+	n = x * M_LOG2E + 0.5;	/* 1/ln(2) = log2(e), 0.5 added for rounding */
+	xn = n;
+	{
+		double	x1 = (long) x;
+		double	x2 = x - x1;
+
+		g = ((x1-xn*0.693359375)+x2) - xn*(-2.1219444005469058277e-4);
+	}
+	if (negative) {
+		g = -g;
+		n = -n;
+	}
+	xn = g * g;
+	x = g * POLYNOM2(xn, p);
+	n += 1;
+	return (Ldexp(0.5 + x/(POLYNOM3(xn, q) - x), n));
+}