function fout = foutperc(A, Ak)
% given matrix A and its approximation Ak
% determine percentage error in function values
% difference in A - Ak in percentage is given
    [m, n] = size(A);
    B = A - Ak;

    % ik heb de loops in elkaar geschoven, vanwege leesbaarheid en
    % snelheid
    magA = 0.0;
    magB = 0.0;
        for i=1:m
            for j=1:n
                magA = magA + abs(A(i,j));
                magB = magB + abs(B(i,j));
            end
        end
    magA = magA / (m * n);
    magB = magB / (m * n);
    fout = magB * 100 / magA;