In the matrix_integer_dense charpoly() function, there is a note in the docstring which says "Linbox charpoly disabled on 64-bit machines, since it hangs in many cases."
As far as I can tell, that is not true, in the sense that (1) I have 64-bit machines, and Linbox charpoly is not disabled, (2) charpoly(algorithm='flint') is so horribly broken that if it were ever used it should be quickly noticed that it is broken, and (3) I can't see anywhere where it is actually disabled. So I actually just submitted a patch which removes this note while fixing point (2). (Trac #21596). However... In some testing I'm noticing problems with charpoly(), so I'm wondering where that message came from, and who knows something about it. The problems seem the likely cause of #21579, though I haven't actually been able to conclusively blame that on linbox yet. I'm also not sure I've seen linbox's charpoly() hang, exactly, but I do see very erratic behavior in how long it takes: on a fixed matrix I have it typically takes 30 seconds, but I've also seen it return the correct answer after 50 minutes. (I've also got the wrong answer sometimes, but there are some conversions going on, and I've so far only seen the wrong answer for rational matrices, which is why I've not get blamed linbox, though I am certainly leaning towards blaming it.) Note: I'm currently testing on 7.4.beta6, so this is after the recent linbox upgrade. But I was also having some problems before that. It is possible that the recent upgrade made errors less likely, though. -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
