Let's say I have an array in Matlab: x = [1 1 1 2 2 2 3 3 3 3 2 2 3 3 3 1 1 1 1 1 2 2 2 2 3 3 3] I want the indices of the most recent set of consecutive '1's. In this case, I want the answer: answer = [16 17 18 19 20] % (which should correspond to the last sequence of 1's) I need an automated way to do this in Matlab, that will work with any size arrays, always giving me the indices for the last set of consecutive 1s. Any suggestions?