function z=lcgshuffle(x,y,m2,k)
%input two long sequences of x nd y. shuffles the sequence x using the sequence y and k bins
i=ceil(k*(y+.5)/m2);   z=[]; m=[];
T=x(1:k);
for j=1:(length(x)-4)
    z=[z T(i(j))];
    T(i(j))=x(j+4);
end
%test period by looking for a repetition of the first 9 numbers.
for j=10:(length(z)-8)
    m=[m sum(z(1:9)==z(j:(j+8)))];
end
['maximum length of repeated string (first 9 digits) ',num2str(max(m))]