#2957: [with patch, needs work] Singular multivariate polynomials are buggy on
exponent overflow
------------------------------+---------------------------------------------
Reporter: cwitty | Owner: somebody
Type: defect | Status: new
Priority: major | Milestone: sage-3.4.1
Component: basic arithmetic | Resolution:
Keywords: |
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Changes (by burcin):
* summary: [with patch, needs review] Singular multivariate polynomials
are buggy on exponent overflow => [with patch,
needs work] Singular multivariate polynomials
are buggy on exponent overflow
Comment:
We already discussed this with malb, boothby and was extensively. Here are
the points here for reference:
* the return value of the function `p_GetMaxExp` is an unsigned long,
fixing this should let one remove the esum < 0 check
* `max_exponent_size` in `multi_polynomial_libsingular.pyx` should be
declared an `unsigned long`
* adding an `unlikely` hint for `esum > max_exponent_size` might reduce
the speed regression even further
Boothby also remarked that checking for total degree before the degree of
each variable might help. Looking at the code again, I think we only check
the total degree.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/2957#comment:5>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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