Mult.java

// return C = A * B
public static double[][] multiply(double[][] A, double[][] B) 
{
	int mA = A.length; //row
	int nA = A[0].length; //col
	int mB = B.length;
	int nB = A[0].length;
	if (nA != mB) 
		throw new RuntimeException("Illegal matrix dimensions.");
	double[][] C = new double[mA][nB];
	for (int i = 0; i < mA; i++)
		for (int j = 0; j < nB; j++)
			for (int k = 0; k < nA; k++)
				C[i][j] += (A[i][k] * B[k][j]);
        return C;
}

public Matrix multiply(Matrix b)
{
	if((rows()!=B.rows()) || (cols()!=B.cols())) 
	{
       		System.out.println("Error, cannot add since the 2 matrices do not have the same dimensions.");
       		System.exit(0);
       	}
       	Matrix c = new Matrix(rows(), cols());
       	for(int i = 1; i < rows(); i++)
       		for(int j = 1; j < b.rows(); j++)
       			for(int k = 1; k < cols(); k++)
       				c.set(i, j, c.get(i, j) + get(i, k) * b.get(k, j));
       	return c;
}