function d = tavolsag(p, w, b)
    per = min(size(p) == [3 1]);
    wer = min(size(w) == [3 1]);
    ber = min(size(b) == [1 1]);
    if ~per; fprintf('Ervenytelen p!\n'); end
    if ~wer; fprintf('Ervenytelen w!\n'); end
    if ~ber; fprintf('Ervenytelen b!\n'); end
    if per & wer & ber
        d = abs((w' * p + b) / sqrt(w' * w));
    end
end