trouble translating pseudo code for decimal number to base b

I was given the following pseudo code however because of matlabs arrays starting at 1 and other issues im running into i cant really translate it and its really confusing.

I managed to translate the "base(z,b)" properly which translates an int to a base b number.

I cant really get behind why some indices are -k. the output doesnt really make much sense either.

Pseudocode:

decimaltobase(z,b):
nums = base(z,b);
r[0] = z - floor(z);
k = 0;
period = 0;
while period == 0 && r[k] != 0:
    k = k + 1;
    r[k] = b * r[k - 1];
    z[-k] = r[k] - z[-k];
    if r[k] == r[p] for any p < k: 
            period = 1;
            store p;
            if rk == 0:
                return nums;
            else:
                return nums "." r;

my code:

function y = decimaltobase(z,b)
    nums = base(floor(z),b);
    r(1) = z - floor(z);
    k = 1;
    period = 1;
    while period == 1 && r(k) ~= 0
        k = k + 1;
        r(k) = b * r(k - 1);
        z(k) = floor(r(k));
        r(k) = r(k) - z(k);
        pfound = false;
        if pfound == false
            p = 1;
        end
        while p < k
            disp(p)
            disp(k)
            if r(k) == r(p)
                period = 1;
                pfound = true;
            else
                p = p + 1;
            end
        end
        
    end
    y = horzcat(nums,".",r);
end

[Stephen23]

That does not look like pseudo-code, it looks like Python code. In which case [-1] is the last element in an iterable, and [-k] is the k-th last element. To do something similar in MATLAB you would use END.

Rather than reinventing the wheel, you might like to consider using John D'Errico's excellent fex contribution:

https://www.mathworks.com/matlabcentral/fileexchange/58850-base2base-nstart-bstart-bend

[Tom Schneider]

ah yes, i didnt think abt the k-th last element thank you very much. unfortunately this is a project for uni so I, in fact, have to reinvent the wheel 😂