math.h

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/*
 * $Revision: 2027 $
 * 
 * last checkin:
 *   $Author: gutwenger $ 
 *   $Date: 2010-09-01 11:55:17 +0200 (Wed, 01 Sep 2010) $ 
 ***************************************************************/
 
#ifndef OGDF_MATH_H
#define OGDF_MATH_H

namespace ogdf {

#define DOUBLE_EPS 0.000001

class OGDF_EXPORT Math {
public:
    inline static int binomial(int n, int k) {
        if(k>n/2) k = n-k;
        int r = n;
        for(int i = 2; i<=k; ++i)
            r = (r * (n+1-i))/i;
        return r;
    }
    inline static double binomial(double n, double k) {
        if(k>n/2) k = n-k;
        double r = n;
        for(int i = 2; i<=k; ++i)
            r = (r * (n+1-i))/i;
        return r;
    }
    static int factorial(int n) {
        int r = 1;
        for(; n>1; --n) r *= n;
        return r;
    }

    static double factorial(double n) {
        double r = 1;
        for(; n>1; --n) r *= n;
        return r;
    }

    inline bool equald(double a, double b) {
        double d = a-b;
        return d < DOUBLE_EPS && d > -DOUBLE_EPS;
    }
};


}

#endif // OGDF_MATH_H