Determinant.h

Go to the documentation of this file.

/*
 * Expression Template Matrix Library
 *
 * Copyright (C) 2004 - 2006 Ricky Lung <mtlung@users.sourceforge.net>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */


#ifdef _MSC_VER
#   pragma once
#   pragma warning( push )
#   pragma warning( disable : 4127 4786 )
#endif  // _MSC_VER

#ifndef EXMAT_MATH_DETERMINANT_H
#define EXMAT_MATH_DETERMINANT_H


namespace exmat {

namespace PNS {
    template<size_t N> struct DeterminantComplexity {
        enum {
            RET = N * (DeterminantComplexity<N-1>::RET + 3)
        };
    };
    template<> struct DeterminantComplexity<1>
    {   enum { RET = 0 };   };
    template<> struct DeterminantComplexity<2>
    {   enum { RET = 3 };   };
    template<> struct DeterminantComplexity<3>
    {   enum { RET = 17 };  };

    template<class Rep, class ErrChk>
    EXMAT_INLINE1 static typename Rep::value_type
    determinant(const Mat<Rep,ErrChk>& m, Int2Type<0>) {
        switch(m.rows()) {
        case 1:
            return determinant(m, Int2Type<1>()); break;
        case 2:
            return determinant(m, Int2Type<2>()); break;
        case 3:
            return determinant(m, Int2Type<3>()); break;
        default:
            THROWMSG(true, "Sorry not yet implemented", __FILE__);
            break;
        }
        return 0;
    }
    template<class Rep, class ErrChk>
    EXMAT_INLINE2 static typename Rep::value_type
    determinant(const Mat<Rep,ErrChk>& m, Int2Type<1>) {
        return m.getAt(0,0);
    }
    template<class Rep, class ErrChk>
    EXMAT_INLINE2 static typename Rep::value_type
    determinant(const Mat<Rep,ErrChk>& m, Int2Type<2>) {
        return m.getAt(0,0) * m.getAt(1,1) - m.getAt(1,0) * m.getAt(0,1);
    }
    template<class Rep, class ErrChk>
    EXMAT_INLINE1 static typename Rep::value_type   // Note: Should not use force inline
    determinant(const Mat<Rep,ErrChk>& m, Int2Type<3>) {
        return
            m.getAt(0,0) * m.getAt(1,1) * m.getAt(2,2) +
            m.getAt(0,1) * m.getAt(1,2) * m.getAt(2,0) +
            m.getAt(0,2) * m.getAt(1,0) * m.getAt(2,1) -
            m.getAt(0,2) * m.getAt(1,1) * m.getAt(2,0) -
            m.getAt(0,0) * m.getAt(1,2) * m.getAt(2,1) -
            m.getAt(0,1) * m.getAt(1,0) * m.getAt(2,2);
    }
#if HAVE_PARTIAL_SPECIALIZATION
    template<class Rep, class ErrChk, size_t I>
    EXMAT_INLINE1 static typename Rep::value_type   // Note: Should not use force inline
    determinant(const Mat<Rep,ErrChk>& m, Int2Type<I>);
#endif
}   // namespace PNS

template<class Rep, class ErrChk>
EXMAT_INLINE2 static typename Rep::value_type
determinant(const Mat<Rep,ErrChk>& m) {
    typedef typename Rep::value_type value_type;
    THROWMSG(m.rows() != 0 && m.rows() == m.cols(), IncompatibleErrMsg, __FILE__);
    return exmat::PNS::determinant(m, Int2Type<HAVE_PARTIAL_SPECIALIZATION ? Rep::ROWS : 0>());
}


}   // namespace exmat

#ifdef _MSC_VER
#   pragma warning( pop )
#endif  // _MSC_VER

#endif  // EXMAT_MATH_DETERMINANT_H

---