On Sun, Jul 22, 2012 at 3:47 AM, Sergiu Ivanov <[email protected]> wrote: > On Sun, Jul 22, 2012 at 9:31 AM, Aaron Meurer <[email protected]> wrote: >> On Jul 16, 2012, at 4:36 AM, Sergiu Ivanov <[email protected]> >> wrote: >> >>> On Mon, Jul 16, 2012 at 1:19 PM, [email protected] >>> <[email protected]> wrote: >>>> With all the issues surrounding ordering, hashes and hash >>>> randomization I was left with the impression that we should rewrite >>>> tests in such a way that they test for mathematical correctness but >>>> not for specific ordering of args, etc. >>> >>> Since we are discussing this, I would like to state that not forcing >>> the ordering in some cases leads to an unpleasant variety of results. >>> For example, in computing eigenvectors, this leads to _different_ >>> eigenvectors at different runs. They are not essentially different, >>> of course, but they are still different and this sounds a lot like a >>> concealed bomb. >> >> I'm curious, do these eigenvectors differ only by constants, or is it >> a case of completely different linear combinations with some >> eigenvalues of high geometric degree? > > I can't produce the exact example off-hand (I can do that, however, > should the need be), but from what I remember, the eigenvectors would > have components in different order, i.e., something like [0, 1, 2] in > one run and [2, 0, 1] in another.
This is the eigenvalues or eigenvector? [0, 1, 2] and [2, 0, 1] are linearly independent, so unless there was also another differing eigenvector corresponding to the same eigenvalue, I don't see how that could have happened. Aaron Meurer > > Sergiu > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/sympy?hl=en. > -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
