Hi, I don't get any error message when trying to index matrices beyond their actual dimensions, see the example script below. Don't know if it's a bug or a missing feature but the information would be very helpful for debugging (as I just learned the hard way)... thanks, sven open denmark matrix check = I(4) tix = 1 loop while tix<=5 print tix matrix my = check[5,] tix = tix + 1 end loop