Opened 5 years ago
Closed 5 years ago
#17675 closed defect (fixed)
xgcd(2,2) hangs forever in ZZ['x']
Reported by:  vdelecroix  Owned by:  

Priority:  critical  Milestone:  sage6.5 
Component:  algebra  Keywords:  
Cc:  wbhart  Merged in:  
Authors:  Vincent Delecroix  Reviewers:  Ralf Stephan 
Report Upstream:  Reported upstream. Developers deny it's a bug.  Work issues:  
Branch:  cf9d62b (Commits)  Commit:  cf9d62b6b0961ece59ae1e3cfdff6becc8da5b57 
Dependencies:  Stopgaps: 
Description (last modified by )
On sage6.5.beta6 we have
sage: R.<x> = ZZ['x'] sage: R(2).xgcd(R(2)) # be prepared to wait
It is a problem in our way to use the FLINT function fmpz_poly_xgcd
. As Bill reported on this sagedevel thread it does not work for input which are constant polynomials (note that it is already a bit more general that what is indicated in FLINT documentation: the function assumes that f and g are primitive (have Gaussian content equal to 1). The result is undefined otherwise.)
See also this FLINT bug report.
Change History (13)
comment:1 Changed 5 years ago by
 Cc wbhart added
comment:2 followup: ↓ 3 Changed 5 years ago by
 Report Upstream changed from N/A to Reported upstream. No feedback yet.
comment:3 in reply to: ↑ 2 Changed 5 years ago by
 Description modified (diff)
Replying to rws:
Reported at https://github.com/wbhart/flint2/issues/112
Thanks Ralf! I was not enough familiar to FLINT (and it was late after the bug tracking) to write the sample program.
Vincent
comment:4 Changed 5 years ago by
 Report Upstream changed from Reported upstream. No feedback yet. to Reported upstream. Developers deny it's a bug.
comment:5 Changed 5 years ago by
 Branch set to u/vdelecroix/17675
 Commit set to d05ac70434cafd7986e5e01671e1982e7fc8ffdc
 Status changed from new to needs_review
As reported by Bill on sagedevel the only trouble was for constant input. In the commit I just treat this case first in the function xgcd... needs review!
Vincent
New commits:
d05ac70  trac #17675: fix xgcd of constant integer polynomials

comment:6 Changed 5 years ago by
Typos found: sucht that
, trivial casess
.
comment:7 Changed 5 years ago by
 Commit changed from d05ac70434cafd7986e5e01671e1982e7fc8ffdc to a439152b4971501edd7e856d8e2c62681c6c9d08
Branch pushed to git repo; I updated commit sha1. New commits:
a439152  trac #17675: doc typo

comment:8 Changed 5 years ago by
 Commit changed from a439152b4971501edd7e856d8e2c62681c6c9d08 to f0d7ca3a02d79b66820aad2289ba5d0809ec9c3e
Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:
f0d7ca3  trac #17675: doc typo

comment:9 Changed 5 years ago by
 Description modified (diff)
comment:10 Changed 5 years ago by
 Branch changed from u/vdelecroix/17675 to u/rws/17675
comment:11 Changed 5 years ago by
 Commit changed from f0d7ca3a02d79b66820aad2289ba5d0809ec9c3e to cf9d62b6b0961ece59ae1e3cfdff6becc8da5b57
 Reviewers set to Ralf Stephan
 Status changed from needs_review to positive_review
I fixed a typo. Looks fine now and passes make ptestlong
. I dare to fill the author field with your name.
New commits:
cf9d62b  17675: reviewer's patch: fix typo

comment:12 Changed 5 years ago by
Great! Thanks for the quick review.
Vincent
comment:13 Changed 5 years ago by
 Branch changed from u/rws/17675 to cf9d62b6b0961ece59ae1e3cfdff6becc8da5b57
 Resolution set to fixed
 Status changed from positive_review to closed
Reported at https://github.com/wbhart/flint2/issues/112