//===========================================================================
// Copyright (C) 1998, 2000-2007, 2010, 2011, 2012 SINTEF ICT, Applied
// Mathematics, Norway.
//
// This file is part of GoTools
//
// 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 the Free Software Foundation version 2 of the License. 
//
// 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.                           
//
// You should have received a copy of the GNU General Public License      
// along with this program; if not, see <http://www.gnu.org/licenses>
//
// Contact information: E-mail: tor.dokken@sintef.no                      
// SINTEF ICT, Department of Applied Mathematics,                         
// P.O. Box 124 Blindern,                                                 
// 0314 Oslo, Norway.                                                     
//
// Other licenses are also available for this software, notably licenses
// for:
// - Building commercial software.                                        
// - Building software whose source code you wish to keep private.        
//===========================================================================

#ifndef _FACTORIAL_H
#define _FACTORIAL_H


namespace Go {


/// Compile-time factorial calculations.


/// Calculate the factorial of a given integer N.
template<int N>
struct Factorial {
    enum { value = N * Factorial<N-1>::value };
};


/// \internal
template <>
struct Factorial<1> {
    enum { value = 1 };
};


/// Compute the inverse of the factorial of a given integer N, where
/// T is typically 'float' or 'double'.
template<typename T, int N>
struct InverseFactorial {
    static inline T val()
    {
	return T(1) / T(Factorial<N>::value);
    }
};
 

};
#endif // _FACTORIAL_H

