* Some timings on series expansion of the Gamma function around a pole. */
/*
- * GiNaC Copyright (C) 1999-2000 Johannes Gutenberg University Mainz, Germany
+ * GiNaC Copyright (C) 1999-2004 Johannes Gutenberg University Mainz, Germany
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
{
unsigned result = 0;
symbol x;
-
+
ex myseries = series(tgamma(x),x==0,order);
// compute the last coefficient numerically:
ex last_coeff = myseries.coeff(x,order-1).evalf();
// compute a bound for that coefficient using a variation of the leading
// term in Stirling's formula:
- ex bound = evalf(exp(ex(-.57721566490153286*(order-1)))/(order-1));
- if (evalf(abs((last_coeff-pow(-1,order))/bound)) > numeric(1)) {
+ ex bound = exp(-.57721566490153286*(order-1))/(order-1);
+ if (abs((last_coeff-pow(-1,order))/bound) > 1) {
clog << "The " << order-1
- << "th order coefficient in the power series expansion of tgamma(0) was erroneously found to be "
- << last_coeff << ", violating a simple estimate." << endl;
+ << "th order coefficient in the power series expansion of tgamma(0) was erroneously found to be "
+ << last_coeff << ", violating a simple estimate." << endl;
++result;
}
-
+
return result;
}
-unsigned time_gammaseries(void)
+unsigned time_gammaseries()
{
unsigned result = 0;
-
+
cout << "timing Laurent series expansion of Gamma function" << flush;
clog << "-------Laurent series expansion of Gamma function:" << endl;
-
+
vector<unsigned> sizes;
vector<double> times;
timer omega;
-
+
sizes.push_back(10);
sizes.push_back(15);
sizes.push_back(20);
sizes.push_back(25);
-
+
for (vector<unsigned>::iterator i=sizes.begin(); i!=sizes.end(); ++i) {
omega.start();
result += tgammaseries(*i);
times.push_back(omega.read());
cout << '.' << flush;
}
-
+
if (!result) {
cout << " passed ";
clog << "(no output)" << endl;