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/*
* $Revision: 2549 $
*
* last checkin:
* $Author: gutwenger $
* $Date: 2012-07-04 23:09:19 +0200 (Mi, 04. Jul 2012) $
***************************************************************/
/** \file
* \brief Implementation of mathematical constants, functions.
*
* \author Carsten Gutwenger
*
* \par License:
* This file is part of the Open Graph Drawing Framework (OGDF).
*
* \par
* Copyright (C)<br>
* See README.txt in the root directory of the OGDF installation for details.
*
* \par
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* Version 2 or 3 as published by the Free Software Foundation;
* see the file LICENSE.txt included in the packaging of this file
* for details.
*
* \par
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* \par
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
* \see http://www.gnu.org/copyleft/gpl.html
***************************************************************/
#include "Math.h"
#include <limits.h>
namespace ogdf {
const double Math::pi = 3.14159265358979323846;
const double Math::pi_2 = 1.57079632679489661923;
const double Math::pi_4 = 0.785398163397448309616;
const double Math::two_pi = 2*3.14159265358979323846;
const double Math::e = 2.71828182845904523536;
const double Math::log_of_2 = log(2.0);
const double Math::log_of_4 = log(4.0);
int factorials[13] = {
1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880,
3628800, 39916800, 479001600
};
double factorials_d[20] = {
1.0, 1.0, 2.0, 6.0, 24.0, 120.0, 720.0, 5040.0, 40320.0, 362880.0,
3628800.0, 39916800.0, 479001600.0, 6227020800.0, 87178291200.0,
1307674368000.0, 20922789888000.0, 355687428096000.0,
6402373705728000.0, 121645100408832000.0
};
int Math::binomial(int n, int k)
{
if(k>n/2) k = n-k;
if(k == 0) return 1;
int r = n;
for(int i = 2; i<=k; ++i)
r = (r * (n+1-i))/i;
return r;
}
double Math::binomial_d(int n, int k)
{
if(k>n/2) k = n-k;
if(k == 0) return 1.0;
double r = n;
for(int i = 2; i<=k; ++i)
r = (r * (n+1-i))/i;
return r;
}
int Math::factorial(int n)
{
if(n < 0) return 1;
if(n > 12) return INT_MAX; // not representable by int
return factorials[n];
}
double Math::factorial_d(int n)
{
if(n < 0) return 1.0;
double f = 1.0;
for(; n > 19; --n)
f *= n;
return f * factorials_d[n];
}
} // namespace ogdf
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