Dear all,
I am writing to ask for help with analysing a very strange problem
that came up a few days ago on trac ticket #4000.
After reviving the work from last September/ October with some
significant help of Mike Hansen at Sage Days 19 a week ago, we finally
had a version of the patch that applied cleanly to 4.3.1.rc0 (plus the
three patches by Robert Bradshaw from #383) and, at least on my
machine and another departmental machine, passed all doctests.
However, when Alex Ghitza had a look at this, he noticed a doctest
failure with his setup. It turns out that he can already produce an
error with the commands
sage: R.<x> = QQ[]
sage: f = 3/2*x - 1/3
sage: %time _ = f % f
Error: unable to alloc/realloc memory
Unfortunately, I cannot reproduce the crash on my machine. What is
perhaps even stranger (at least to me!) is the fact the exact same
code as above takes 20s on my machine to execute, and when I modify
part of the relevant Cython code to look like 1. print "A" 2. FLINT
call 3. print "B" 4. FLINT call, I get to see the output "A", then
wait for a few seconds, then see "B", which is followed by some more
waiting. Although I couldn't quite believe it, this led me to at
least consider the possibility that with the specific inputs the FLINT
calls might be broken and actually take this long. However, I did not
manage to reproduce the same example as an example in plain C code.
I'd be very grateful for any ideas on how this issue might be
resolved.
Many thanks,
Sebastian
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