Matrix operations

Hi all, I'm not a pro at Matlab, but I'm trying. Can anyone offer help with the following:

[M] - [K] = [L]*[H]*[H]'*[L]'...... where [M]-[K}>0

All are matrices, I know M, K and L, how do I solve for H and H' such that I maintain positive definiteness of M-K?

I have tried to use Cholesky method but I cannot get it to work. Any help would be appreciated. Thanks.