symbian-qemu-0.9.1-12/python-2.6.1/Python/pymath.c
changeset 1 2fb8b9db1c86
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/symbian-qemu-0.9.1-12/python-2.6.1/Python/pymath.c	Fri Jul 31 15:01:17 2009 +0100
@@ -0,0 +1,234 @@
+#include "Python.h"
+
+#ifndef HAVE_HYPOT
+double hypot(double x, double y)
+{
+	double yx;
+
+	x = fabs(x);
+	y = fabs(y);
+	if (x < y) {
+		double temp = x;
+		x = y;
+		y = temp;
+	}
+	if (x == 0.)
+		return 0.;
+	else {
+		yx = y/x;
+		return x*sqrt(1.+yx*yx);
+	}
+}
+#endif /* HAVE_HYPOT */
+
+#ifndef HAVE_COPYSIGN
+static double
+copysign(double x, double y)
+{
+	/* use atan2 to distinguish -0. from 0. */
+	if (y > 0. || (y == 0. && atan2(y, -1.) > 0.)) {
+		return fabs(x);
+	} else {
+		return -fabs(x);
+	}
+}
+#endif /* HAVE_COPYSIGN */
+
+#ifndef HAVE_LOG1P
+#include <float.h>
+
+double
+log1p(double x)
+{
+	/* For x small, we use the following approach.  Let y be the nearest
+	   float to 1+x, then
+
+	     1+x = y * (1 - (y-1-x)/y)
+
+	   so log(1+x) = log(y) + log(1-(y-1-x)/y).  Since (y-1-x)/y is tiny,
+	   the second term is well approximated by (y-1-x)/y.  If abs(x) >=
+	   DBL_EPSILON/2 or the rounding-mode is some form of round-to-nearest
+	   then y-1-x will be exactly representable, and is computed exactly
+	   by (y-1)-x.
+
+	   If abs(x) < DBL_EPSILON/2 and the rounding mode is not known to be
+	   round-to-nearest then this method is slightly dangerous: 1+x could
+	   be rounded up to 1+DBL_EPSILON instead of down to 1, and in that
+	   case y-1-x will not be exactly representable any more and the
+	   result can be off by many ulps.  But this is easily fixed: for a
+	   floating-point number |x| < DBL_EPSILON/2., the closest
+	   floating-point number to log(1+x) is exactly x.
+	*/
+
+	double y;
+	if (fabs(x) < DBL_EPSILON/2.) {
+		return x;
+	} else if (-0.5 <= x && x <= 1.) {
+		/* WARNING: it's possible than an overeager compiler
+		   will incorrectly optimize the following two lines
+		   to the equivalent of "return log(1.+x)". If this
+		   happens, then results from log1p will be inaccurate
+		   for small x. */
+		y = 1.+x;
+		return log(y)-((y-1.)-x)/y;
+	} else {
+		/* NaNs and infinities should end up here */
+		return log(1.+x);
+	}
+}
+#endif /* HAVE_LOG1P */
+
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+static const double ln2 = 6.93147180559945286227E-01;
+static const double two_pow_m28 = 3.7252902984619141E-09; /* 2**-28 */
+static const double two_pow_p28 = 268435456.0; /* 2**28 */
+static const double zero = 0.0;
+
+/* asinh(x)
+ * Method :
+ *	Based on 
+ *		asinh(x) = sign(x) * log [ |x| + sqrt(x*x+1) ]
+ *	we have
+ *	asinh(x) := x  if  1+x*x=1,
+ *		 := sign(x)*(log(x)+ln2)) for large |x|, else
+ *		 := sign(x)*log(2|x|+1/(|x|+sqrt(x*x+1))) if|x|>2, else
+ *		 := sign(x)*log1p(|x| + x^2/(1 + sqrt(1+x^2)))  
+ */
+
+#ifndef HAVE_ASINH
+double
+asinh(double x)
+{	
+	double w;
+	double absx = fabs(x);
+
+	if (Py_IS_NAN(x) || Py_IS_INFINITY(x)) {
+		return x+x;
+	}
+	if (absx < two_pow_m28) {	/* |x| < 2**-28 */
+		return x;	/* return x inexact except 0 */
+	} 
+	if (absx > two_pow_p28) {	/* |x| > 2**28 */
+		w = log(absx)+ln2;
+	}
+	else if (absx > 2.0) {		/* 2 < |x| < 2**28 */
+		w = log(2.0*absx + 1.0 / (sqrt(x*x + 1.0) + absx));
+	}
+	else {				/* 2**-28 <= |x| < 2= */
+		double t = x*x;
+		w = log1p(absx + t / (1.0 + sqrt(1.0 + t)));
+	}
+	return copysign(w, x);
+	
+}
+#endif /* HAVE_ASINH */
+
+/* acosh(x)
+ * Method :
+ *      Based on
+ *	      acosh(x) = log [ x + sqrt(x*x-1) ]
+ *      we have
+ *	      acosh(x) := log(x)+ln2, if x is large; else
+ *	      acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x>2; else
+ *	      acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t=x-1.
+ *
+ * Special cases:
+ *      acosh(x) is NaN with signal if x<1.
+ *      acosh(NaN) is NaN without signal.
+ */
+
+#ifndef HAVE_ACOSH
+double
+acosh(double x)
+{
+	if (Py_IS_NAN(x)) {
+		return x+x;
+	}
+	if (x < 1.) {			/* x < 1;  return a signaling NaN */
+		errno = EDOM;
+#ifdef Py_NAN
+		return Py_NAN;
+#else
+		return (x-x)/(x-x);
+#endif
+	}
+	else if (x >= two_pow_p28) {	/* x > 2**28 */
+		if (Py_IS_INFINITY(x)) {
+			return x+x;
+		} else {
+			return log(x)+ln2;	/* acosh(huge)=log(2x) */
+		}
+	}
+	else if (x == 1.) {
+		return 0.0;			/* acosh(1) = 0 */
+	}
+	else if (x > 2.) {			/* 2 < x < 2**28 */
+		double t = x*x;
+		return log(2.0*x - 1.0 / (x + sqrt(t - 1.0)));
+	}
+	else {				/* 1 < x <= 2 */
+		double t = x - 1.0;
+		return log1p(t + sqrt(2.0*t + t*t));
+	}
+}
+#endif /* HAVE_ACOSH */
+
+/* atanh(x)
+ * Method :
+ *    1.Reduced x to positive by atanh(-x) = -atanh(x)
+ *    2.For x>=0.5
+ *		  1	      2x			  x
+ *      atanh(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------)
+ *		  2	     1 - x		      1 - x
+ *
+ *      For x<0.5
+ *      atanh(x) = 0.5*log1p(2x+2x*x/(1-x))
+ *
+ * Special cases:
+ *      atanh(x) is NaN if |x| >= 1 with signal;
+ *      atanh(NaN) is that NaN with no signal;
+ *
+ */
+
+#ifndef HAVE_ATANH
+double
+atanh(double x)
+{
+	double absx;
+	double t;
+
+	if (Py_IS_NAN(x)) {
+		return x+x;
+	}
+	absx = fabs(x);
+	if (absx >= 1.) {		/* |x| >= 1 */
+		errno = EDOM;
+#ifdef Py_NAN
+		return Py_NAN;
+#else
+		return x/zero;
+#endif
+	}
+	if (absx < two_pow_m28) {	/* |x| < 2**-28 */
+		return x;
+	}
+	if (absx < 0.5) {		/* |x| < 0.5 */
+		t = absx+absx;
+		t = 0.5 * log1p(t + t*absx / (1.0 - absx));
+	} 
+	else {				/* 0.5 <= |x| <= 1.0 */
+		t = 0.5 * log1p((absx + absx) / (1.0 - absx));
+	}
+	return copysign(t, x);
+}
+#endif /* HAVE_ATANH */