Attached is a jupyter notebook that runs Sage 9.1, a (slightly more) minimal example of a problem that I discovered. When calculating the determinant of a large (in the sense n>=9 I have currently found) symbolic matrix the answer is not correct. To see this, run the notebook with Qsimplify either True or False. When Qsimplify is false, the calculation is done when variables lie in the symbolic ring, when true a specially constructed ring is used instead. The output of the script shows a matrix and the resulting characteristic polynomial after some simplification has occured. While the two matrices look the same regardless of Qsimplify, the characteristic polynomial changes. This error goes away for smaller matrices (it first turns up at rank=4, where the rank is of the Lie algebra involved in the calculation, but this just gives the basis the matrix is constructed from). General theory tells us that the answer when Qsimplify is true is the correct one.
-- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/7a7ba119-58cc-4bc8-9785-3bc19ec9e0dan%40googlegroups.com.
Spectral_Curves_reduced.ipynb
Description: application/ipynb
