dmatrix.h

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#ifndef DMATRIX_HXX 
#define DMATRIX_HXX

#include <iostream>
#include <exception>
namespace GMapping {

class DNotInvertibleMatrixException: public std::exception {};
class DIncompatibleMatrixException: public std::exception {};
class DNotSquareMatrixException: public std::exception {};

template <class X> class DMatrix {
        public:
                DMatrix(int n=0,int m=0);
                ~DMatrix();

                DMatrix(const DMatrix&);
                DMatrix& operator=(const DMatrix&);

                X * operator[](int i) {
                        if ((*shares)>1) detach();
                        return mrows[i];
                }

                const X * operator[](int i) const { return mrows[i]; }

                const X det() const;
                DMatrix inv() const;
                DMatrix transpose() const;
                DMatrix operator*(const DMatrix&) const;
                DMatrix operator+(const DMatrix&) const;
                DMatrix operator-(const DMatrix&) const;
                DMatrix operator*(const X&) const;

                int rows() const { return nrows; }
                int columns() const { return ncols; }

                void detach();

                static DMatrix I(int);

        protected:
                int nrows,ncols;
                X * elems;
                X ** mrows;

                int * shares;
};

template <class X> DMatrix<X>::DMatrix(int n,int m) {
        if (n<1) n=1;
        if (m<1) m=1;
        nrows=n;
        ncols=m;
        elems=new X[nrows*ncols];
        mrows=new X* [nrows];
        for (int i=0;i<nrows;i++) mrows[i]=elems+ncols*i;
        for (int i=0;i<nrows*ncols;i++) elems[i]=X(0);
        shares=new int;
        (*shares)=1;
}

template <class X> DMatrix<X>::~DMatrix() {
        if (--(*shares)) return;
        delete [] elems;
        delete [] mrows;
        delete shares;
}

template <class X> DMatrix<X>::DMatrix(const DMatrix& m) {
        shares=m.shares;
        elems=m.elems;
        nrows=m.nrows;
        ncols=m.ncols;
        mrows=m.mrows;
        (*shares)++;
}

template <class X> DMatrix<X>& DMatrix<X>::operator=(const DMatrix& m) {
        if (!--(*shares)) {
                delete [] elems;
                delete [] mrows;
                delete shares;
        }
        shares=m.shares;
        elems=m.elems;
        nrows=m.nrows;
        ncols=m.ncols;
        mrows=m.mrows;
        (*shares)++;
        return *this;
}

template <class X> DMatrix<X> DMatrix<X>::inv() const {
        if (nrows!=ncols) throw DNotInvertibleMatrixException();
        DMatrix<X> aux1(*this),aux2(I(nrows));
        aux1.detach();
        for (int i=0;i<nrows;i++) {
                int k=i;
                for (;k<nrows&&aux1.mrows[k][i]==X(0);k++);
                if (k>=nrows) throw DNotInvertibleMatrixException();
                X val=aux1.mrows[k][i];
                for (int j=0;j<nrows;j++) {
                        aux1.mrows[k][j]=aux1.mrows[k][j]/val;
                        aux2.mrows[k][j]=aux2.mrows[k][j]/val;
                }
                if (k!=i) {
                        for (int j=0;j<nrows;j++) {
                                X tmp=aux1.mrows[k][j];
                                aux1.mrows[k][j]=aux1.mrows[i][j];
                                aux1.mrows[i][j]=tmp;
                                tmp=aux2.mrows[k][j];
                                aux2.mrows[k][j]=aux2.mrows[i][j];
                                aux2.mrows[i][j]=tmp;
                        }
                }
                for (int j=0;j<nrows;j++)
                        if (j!=i) {
                                X tmp=aux1.mrows[j][i];
                                for (int l=0;l<nrows;l++) {
                                        aux1.mrows[j][l]=aux1.mrows[j][l]-tmp*aux1.mrows[i][l];
                                        aux2.mrows[j][l]=aux2.mrows[j][l]-tmp*aux2.mrows[i][l];
                                }
                        }
        }
        return aux2;
}

template <class X> const X DMatrix<X>::det() const {
        if (nrows!=ncols) throw DNotSquareMatrixException();
        DMatrix<X> aux(*this);
        X d=X(1);
        aux.detach();
        for (int i=0;i<nrows;i++) {
                int k=i;
                for (;k<nrows&&aux.mrows[k][i]==X(0);k++);
                if (k>=nrows) return X(0);
                X val=aux.mrows[k][i];
                for (int j=0;j<nrows;j++) {
                        aux.mrows[k][j]/=val;
                }
                d=d*val;
                if (k!=i) {
                        for (int j=0;j<nrows;j++) {
                                X tmp=aux.mrows[k][j];
                                aux.mrows[k][j]=aux.mrows[i][j];
                                aux.mrows[i][j]=tmp;
                        }
                        d=-d;   
                }
                for (int j=i+1;j<nrows;j++){
                        X tmp=aux.mrows[j][i];
                        if (!(tmp==X(0)) ){
                                for (int l=0;l<nrows;l++) {
                                        aux.mrows[j][l]=aux.mrows[j][l]-tmp*aux.mrows[i][l];
                                }
                                //d=d*tmp;
                        }               
                }
        }
        return d;
}

template <class X> DMatrix<X> DMatrix<X>::transpose() const {
        DMatrix<X> aux(ncols, nrows);
        for (int i=0; i<nrows; i++)
                for (int j=0; j<ncols; j++)
                        aux[j][i]=mrows[i][j];
        return aux;
}

template <class X> DMatrix<X> DMatrix<X>::operator*(const DMatrix<X>& m) const {
        if (ncols!=m.nrows) throw DIncompatibleMatrixException();
        DMatrix<X> aux(nrows,m.ncols);
        for (int i=0;i<nrows;i++)
                for (int j=0;j<m.ncols;j++){
                        X a=0;
                        for (int k=0;k<ncols;k++)
                                a+=mrows[i][k]*m.mrows[k][j];
                        aux.mrows[i][j]=a;
                }
        return aux;
}

template <class X> DMatrix<X> DMatrix<X>::operator+(const DMatrix<X>& m) const {
        if (ncols!=m.ncols||nrows!=m.nrows) throw DIncompatibleMatrixException();
        DMatrix<X> aux(nrows,ncols);
        for (int i=0;i<nrows*ncols;i++) aux.elems[i]=elems[i]+m.elems[i];
        return aux;
}

template <class X> DMatrix<X> DMatrix<X>::operator-(const DMatrix<X>& m) const {
        if (ncols!=m.ncols||nrows!=m.nrows) throw DIncompatibleMatrixException();
        DMatrix<X> aux(nrows,ncols);
        for (int i=0;i<nrows*ncols;i++) aux.elems[i]=elems[i]-m.elems[i];
        return aux;
}

template <class X> DMatrix<X> DMatrix<X>::operator*(const X& e) const {
        DMatrix<X> aux(nrows,ncols);
        for (int i=0;i<nrows*ncols;i++) aux.elems[i]=elems[i]*e;
        return aux;
}

template <class X> void DMatrix<X>::detach() {
        DMatrix<X> aux(nrows,ncols);
        for (int i=0;i<nrows*ncols;i++) aux.elems[i]=elems[i];
        operator=(aux);
}

template <class X> DMatrix<X> DMatrix<X>::I(int n) {
        DMatrix<X> aux(n,n);
        for (int i=0;i<n;i++) aux[i][i]=X(1);
        return aux;
}

template <class X> std::ostream& operator<<(std::ostream& os, const DMatrix<X> &m) {
        os << "{";
        for (int i=0;i<m.rows();i++) {
                if (i>0) os << ",";
                os << "{";
                for (int j=0;j<m.columns();j++) {
                        if (j>0) os << ",";
                        os << m[i][j];
                }
                os << "}";
        }
        return os << "}";
}

}; //namespace GMapping 
#endif