Daniel Fetchinson <fetchin...@googlemail.com> writes: > So after all I might just code the inversion via Gauss elimination > myself in a way that can deal with fractions, shouldn't be that hard.
I wouldn't do it that way. Let M be your matrix. Work out the LCM l of the denominators, and multiply the matrix by that to make it an integer matrix N = l M. Then work out the determinant d of that integer matrix. Next, the big step: use Gaussian elimination to find a matrix A (the `adjugate matrix') such that A N = d I. This should be doable entirely using integer arithmetic, and I think without needing any divisions. Finally, we have l A M = d I, so (l/d A) M = I and l/d A is the inverse you seek. Does that make sense? -- [mdw] -- http://mail.python.org/mailman/listinfo/python-list
