C / C++ / MFC

m[i,j] = a[i,0] * b[0,j] +  a[i,1] * b[1,j] + ... +  a[i,N] * b[N,j]

#include <iostream>
#include <string>
using namespace std;


class matrix
{
public:
	struct Exception
	{
		string msg;
		Exception(string emsg)
		{
			this->msg=msg;
		}
	};
	matrix();
	matrix(int m,int n);
        ~matrix(){ delete [] data; }
	int getRows();
	int getCols();

	double& operator()(int, int);

	friend ostream& operator<<(ostream& os, matrix& m);
	matrix operator + (matrix&);
	matrix operator * (matrix&);
	matrix operator - (matrix&);
	matrix operator / (matrix&);

private:
	void init(int, int);
	int nrows,ncols;
	double *data;
};

matrix::matrix(){
	init(1,1);
}

matrix::matrix(int m, int n){
	init(m,n);
}

void matrix::init(int m, int n){
	nrows=m;
	ncols=n;
	data= new double[m*n];
	for(int i=0; i<m*n; i++)
		data[i]=.0;
}

int matrix::getRows() { return nrows;}

int matrix::getCols() { return ncols;}

double& matrix::operator ()(int r, int c){
	if (r <0 || r>= nrows || c<0 || c>= ncols) 
		throw matrix::Exception("out of bounds");
	return data[r*ncols+c];
}

ostream& operator<<(ostream& os, matrix &m)
{
	for(int r=0; r<m.nrows; r++)
	{
		for(int c=0; c < m.ncols; c++)
			os<<m(r,c) << " ";
		os<<endl;
	}
	return os;
}

matrix matrix::operator+(matrix& a)
{
	if ( nrows != a.nrows || ncols!= a.ncols )
		throw Exception("invalid operands");

	matrix sum(nrows, ncols);
	for (int r=0; r<nrows; r++)
		for(int c=0; c<ncols; c++)
		{
			int i = r * ncols + c;
			sum.data[i] = data[i] + a.data[i];
		}
	return sum;
}

matrix matrix::operator*(matrix& a)
{
	matrix product(nrows, ncols);
	for (int r=0; r<nrows; r++)
		for(int c=0; c<ncols; c++)
		{
			product(r,c) = (r,c) * a(r,c);
		}
	return product;
}

matrix matrix::operator-(matrix& a)
{
	
	if ( nrows != a.nrows || ncols!= a.ncols )
	throw Exception("invalid operands");

	matrix difference(nrows, ncols);
	for (int r=0; r<nrows; r++)
		for(int c=0; c<ncols; c++)
		{
			int i = r * ncols + c;
			difference.data[i] = data[i] - a.data[i];
		}
	return difference;
}


matrix matrix::operator/(matrix& a)
{
	matrix divide(nrows, ncols);
	for (int r=0; r<nrows; r++)
		for(int c=0; c<ncols; c++)
			divide(r,c) = (r,c) / a(r,c);
	return divide;
}
int main()
{
	matrix a(2,2);
	a(1,1)=5.0;
	a(0,0)=6.0;
	a(0,1)=7.0;
	a(1,0)=8.0;
	cout<<a(0,0)<<endl;
	cout<<a(1,1)<<endl;
	cout<<a<<endl;

	matrix b(2,2);
	b(0,0) = 5.0;
	b(0,1) = 5.0;
	b(1,0) = 5.0;
	b(1,1) = 5.0;
	cout<<b<<endl;

	matrix c,d,e,f;

	c=a+b;
	d=a*b;
	e=a-b;
	f=a/b;

	cout<<c<<endl;
	cout <<"\n\n";
	cout<<d<<endl;

	cout<<e<<endl;
	cout <<"\n\n";
	cout<<f<<endl;


	system("pause");
	return 0;
}

CPallini wrote:

m[i,j] = a[i,0] * b[0,j] + a[i,1] * b[1,j] + ... + a[i,N] * b[2,N]

Regards.
--------
M.D.V.

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
Rating helpfull answers is nice, but saying thanks can be even nicer.

Nelek wrote:

b[2,N] or b[N,j]?

CPallini wrote:

for instance in relativistic computations

Regards.
--------
M.D.V.

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
Rating helpfull answers is nice, but saying thanks can be even nicer.

Nelek wrote:

CPallini wrote:
for instance in relativistic computations


Oh... I thought it was for quantic physics

ThatsAlok such a long reply..

ThatsAlok happy new year!

Razanust wrote:

a c[slot];