Updating a matrix in a time interval inside a for loop

[deanhystad]

You need to modify the logic. Right now you only save max (or make a copy) if interval coincides with K[ijk] > P[ijk]. You should split the two up.

            if (K[i][j][k]>P[0][j][k]:
                P[0][j][k]=K[i][j][k]
            if i % interval == 0:
                at_intervals.append(copy(P))

This will give you a copy at 0, 10, 20. If you want 9, 19, 29 the test is if (i+1) % interval == 0