Hi Farshud,
You are right, there is a problem in uq_lar. For now, it should work if after line 224 of uq_lar.m
i_coeff(i_coeff == idx) = [];
you add the line
M = pinv(Psi(:,a_coeff)'*Psi(:,a_coeff));
(When a basis element is skipped due to instability, of course also the matrix M needs to be updated.)
We will fix this soon in the code for everyone. Thank you very much for bringing this to our attention!
With this change, your code runs on my computer without problems, also for higher degree PCE. Does it work for you as well?