Hi again, In my set of data, a few has "really" NaN, others has "special" value for it (say -9999 for positive integer arrays). So, I don't want to take in account these values to compute, min, max, mean and so on. How could I do this ? I recall that the arrays are quite "big", ie ~500x500x500 but < 1000x1000x1000. Any clue ? TIA. Cheers, -- Fred