public Matrix subtract(Matrix m) {
		if(numRows != m.numRows || numColumns != m.numColumns)
			throw new IllegalArgumentException("Incompatible dimensions");
		
		Matrix diff = new Matrix(numRows, numColumns);
		for(int i = 0; i < numRows; i++)
			for(int j = 0; j < numColumns; j++)
				diff.elements[i][j] = elements[i][j] - m.elements[i][j];
		
		return diff;
	}