An array x of length n has values 1...m with each value appearing at least once. The values are sorted (n>=m).

A second array y of the same size should be split into elements of a cell array c such that the first element of c contains all elements of y at the positions where x=1 and so on:

x=   [ 1  1  1  2  2  3  3  3  3];
y=   [10 52 12 58 21 43 89 27 98];
c{1}=[10 52 12];
c{2}=[         58 21];
c{3}=[               43 89 27 98];