#12188: Bug in is_smooth for curves over CC
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Reporter: johanbosman | Owner: AlexGhitza
Type: defect | Status: new
Priority: major | Milestone: sage-4.8
Component: algebraic geometry | Keywords: singular
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Changes (by burcin):
* cc: malb, vbraun (added)
Comment:
I'm not sure if this is actually supposed to work in Sage right now.
Multivariate polynomial rings over `CC` use a generic implementation. The
error message should just say "First parameter's ring must be multivariate
polynomial ring via libsingular." This is not entirely clear, but at least
it is a less scary message than "singular_ring_delete(ring*) called with
NULL pointer."
Here is a shorter segment to reproduce the problem:
{{{
sage: P.<X,Y,Z> = CC[]
sage: I = P*X
sage: GroebnerStrategy(I)
File "/home/burcin/sage/sage-4.7.2/local/bin/sage-ipython", line 52, in
<module>
ipy_sage.mainloop(sys_exit=1, banner='')
File "/home/burcin/sage/sage-4.7.2/local/lib/python2.6/site-
packages/IPython/Shell.py", line 76, in mainloop
self.IP.mainloop(banner)
File "/home/burcin/sage/sage-4.7.2/local/lib/python2.6/site-
packages/IPython/iplib.py", line 1762, in mainloop
self.interact(banner)
File "/home/burcin/sage/sage-4.7.2/local/lib/python2.6/site-
packages/IPython/iplib.py", line 2001, in interact
more = self.push(line)
File "/home/burcin/sage/sage-4.7.2/local/lib/python2.6/site-
packages/IPython/iplib.py", line 2305, in push
more = self.runsource('\n'.join(self.buffer), self.filename)
File "/home/burcin/sage/sage-4.7.2/local/lib/python2.6/site-
packages/IPython/iplib.py", line 2231, in runsource
if self.runcode(code) == 0:
File "/home/burcin/sage/sage-4.7.2/local/lib/python2.6/site-
packages/IPython/iplib.py", line 2260, in runcode
exec code_obj in self.user_global_ns, self.user_ns
File "<ipython console>", line 1, in <module>
Exception KeyError: (The ring pointer 0x0,) in ignored
singular_ring_delete(ring*) called with NULL pointer.
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/home/burcin/sage/sage-4.7.2/<ipython console> in <module>()
/home/burcin/sage/sage-4.7.2/local/lib/python2.6/site-
packages/sage/libs/singular/groebner_strategy.so in
sage.libs.singular.groebner_strategy.GroebnerStrategy.__cinit__
(sage/libs/singular/groebner_strategy.cpp:2169)()
TypeError: First parameter's ring must be multivariate polynomial ring via
libsingular.
}}}
This is the message I get after adding an "except +" after the declaration
of `singular_ring_delete()`.
It seems that `GroebnerStrategy.__cinit__()` (why `__cinit__` and not
`__init__`?) already has a doctest for this case. I don't see why the
error message is not caught by the doctesting framework. Are these cython
errors printed to `stderr` now?
In any case, `GroebnerStrategy.__cinit__()` raises an error on line 99 of
`sage/libs/singular/groebner_strategy.pyx`. I thought the `__dealloc__()`
method is not called if there is an error during `__init__()`. Any ideas
what is going wrong here?
I suggest to open a new ticket to use libsingular from multivariate
polynomial rings over CC and RR. This ticket can be about eliminating the
scary `singular_ring_delete` error message.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12188#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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