Also, I meant to thank Daniel Ajoy in the simplematrix source for a sweet little recursive algorithm (which he shared in Logo) for generating all those permutations needed by that greedy determinants algorithm. I'm adding that thank you now and re-uploading. Finally, I never managed to completely solve the devils' embrace problem of importing pyfraction in polynomial, and polynomial in pyfraction. Importing works when I just import, but I want to promote pyfraction.Fraction to the top level in polynomial, so I don't have to write pyfraction.Fraction all the time (especially inconvenient when expanding polynomials with factional coefficients just for evaluation purposes -- a way to stay with integer computations and avoid degenerating to floating points).... That's why you'll see an 'import Fraction from pyfraction', but in the __call__ method of polynomial, and not up top, where it causes problems when I boot Python initially and go 'from mathobjects import *' -- and even if I have an import pyfraction statement first. Any pointers would be appreciated. I think I must be missing something. Kirby