I don't work with complex numbers, but just sampling what others do: Python: no ordering, results in TypeError Matlab: sorts by magnitude http://www.mathworks.com/help/matlab/ref/sort.html R: sorts first by real, then by imaginary http://stat.ethz.ch/R-manual/R-patched/library/base/html/sort.html Numpy: sorts first by real, then by imaginary (the documentation link below calls this sort 'lexicographical' which I don't think is correct) http://docs.scipy.org/doc/numpy/reference/generated/numpy.sort.html I would think that the Matlab sort might be more useful, but easy enough by using the absolute value. I think what Numpy does is normal enough to not justify a warning, but leave this to others because as I pointed out in the beginning I don't work with complex numbers. Kindest regards, Tim