Dear sage supporters,
a strange error occurs in sage 2.10.2 in the following way:
sage: R.<x> = QQ[]
sage: f = x^3 + x + 1; g = x^3 - x - 1
sage: r = f.resultant(g)
sage: R.__dict__
{'_PolynomialRing_general__cyclopoly_cache': {},
'_PolynomialRing_general__generator': x,
'_PolynomialRing_general__is_sparse': False,
'_PolynomialRing_general__polynomial_class': <class
'sage.rings.polynomial.polynomial_element_generic.Polynomial_rational_dense'>,
'_PolynomialRing_singular_repr__singular': // characteristic : 0
// number of vars : 1
// block 1 : ordering lp
// : names x
// block 2 : ordering C,
'_has_singular': True}
Ok so far. Now we use the gap interface and experience a bad surprise:
sage: gap(R.base_ring())
Rationals
sage: R.__dict__
{'_PolynomialRing_general__cyclopoly_cache': {},
'_PolynomialRing_general__generator': x,
'_PolynomialRing_general__is_sparse': False,
'_PolynomialRing_general__polynomial_class': <class
'sage.rings.polynomial.polynomial_element_generic.Polynomial_rational_dense'>,
'_PolynomialRing_singular_repr__singular': print(sage0);
// characteristic : 0
// number of vars : 1
// block 1 : ordering lp
// : names x
// block 2 : ordering C,
'_has_singular': True}
See how R.__dict__['PolynomialRing_singular_repr__singular'] has
changed!
In the first part of the session, it contained a ring, but now it
contains print(sage0).
Even worse: Although sage0 used to be the identifier of the singular
ring associated with R, we now get
sage: singular('sage0')
print(sage8);
sage: sage: singular('sage0')
print(sage9);
sage: sage: singular('sage0')
print(sage10);
and so on!
So, the singular interface seems to be completely messed up. I have no
idea where this behaviour comes from.
Note that the line
sage: r = f.resultant(g)
is essential. When this line is replaced by, e.g.,
sage: singular(R)
the error does not occur. Also, when we first say gap(R.base_ring())
and then compute the resultant, everything is alright.
Perhaps this helps to detect the bug.
Any idea? Shall i open a ticket?
Yours
Simon
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to sage-support@googlegroups.com
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/sage-support
URLs: http://www.sagemath.org
-~----------~----~----~----~------~----~------~--~---
