public rel[real, real, real] matrixMultiplication(rel[real x, real y, real v] matrix1, rel[real x, real y, real v] matrix2){
	if (max(matrix1.x) == max(matrix2.y)){
		p = {<x1,y1,x2,y2, v1*v2> | <x1,y1,v1> <- matrix1, <x2,y2,v2> <- matrix2};

		result = {};
		for (y <- matrix1.y){
			for (x <- matrix2.x){
				v = (0.0 | it + v | <x1, y1, x2, y2, v> <- p,  x==x2 && y==y1, x1==y2 && y2==x1);
				result += <x,y,v>;
			}
		}
		return result;
	}
	else throw "Matrix sizes do not match.";

//a matrix, given by a relation of the x-coordinate, y-coordinate and value.
public rel[real x, real y, real v] matrixA = {
<0.0,0.0,12.0>, <0.0,1.0, 6.0>, <0.0,2.0,-4.0>,
<1.0,0.0,-51.0>, <1.0,1.0,167.0>, <1.0,2.0,24.0>,
<2.0,0.0,4.0>, <2.0,1.0,-68.0>, <2.0,2.0,-41.0>
};