isPeriodic.sce

// BROKEN
// BROKEN
// BROKEN
// BROKEN

function returnString=isPeriodic(P)
    // initialize entered and left
    for i=1:size(P, 1)
        for j=1:size(P, 2)
            entered(i, j) = %F
            left(i, j) = %F
        end
    end

    // search all edges for connections
    for i=1:size(P, 1)
        for j=1:size(P, 2)
            if entered(i, j) == %F then
                [entered, left, foundCircle] = findCircle(P, entered, left, i)
                if foundCircle == %T then
                    returnString = "periodisch"
                    return
                end
            end
        end
    end
    disp(entered, left)
    returnString="nicht periodisch"
endfunction

function [entered, left, foundCircle]=findCircle(P, entered, left, i)
    foundCircle = %F
    entered(i, j) = %T
    for k=1:size(P, 2)
        
        if i <> k & P(i, k) == 1 then
            //disp(entered, "entered")
            //disp(left, "left")
            if entered(i, k) == %F then
                [entered, left, foundCircle] = findCircle(P, entered, left, k)
                if foundCircle == %T then
                    return
                end
            else
                if left(i, k) == %F then
                    // we were already here but couldn't leave, so we know
                    // that the matrix is not periodical
                    foundCircle = %T
                    return
                end
            end
        end
    end
    left(i, j) = %T
endfunction