#14888: Make FiniteField_pari_ffelt the default for generic finite fields
-------------------------------------------+-------------------------------
Reporter: pbruin | Owner: cpernet
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-5.12
Component: finite rings | Resolution:
Keywords: FiniteField performance | Merged in:
Authors: Peter Bruin | Reviewers: Jean-Pierre
Report Upstream: N/A | Flori
Branch: | Work issues:
Dependencies: #12142 | Commit:
| Stopgaps:
-------------------------------------------+-------------------------------
Comment (by jdemeyer):
The first problem is in the following code:
{{{
elif isinstance(x, int) or isinstance(x, long):
g = (<pari_gen>self._parent._gen_pari).g
sig_on()
x_GEN = stoi(x)
self.construct(INT_to_FFELT(g, x_GEN))
}}}
The Python `long` type doesn't convert to a C `long` (confusingly, a `C`
long corresponds to a Python `int`).
To see the problem on 64 bits (let this inspire a doctest):
{{{
sage: GF(7^20, 'a')(long(2^63))
---------------------------------------------------------------------------
OverflowError Traceback (most recent call
last)
<ipython-input-18-d85771ca8953> in <module>()
----> 1 GF(Integer(7)**Integer(20), 'a')(long(Integer(2)**Integer(63)))
/mazur/release/merger/sage-5.12.beta4/local/lib/python2.7/site-
packages/sage/structure/parent.so in sage.structure.parent.Parent.__call__
(sage/structure/parent.c:8372)()
/mazur/release/merger/sage-5.12.beta4/local/lib/python2.7/site-
packages/sage/structure/coerce_maps.so in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3856)()
/mazur/release/merger/sage-5.12.beta4/local/lib/python2.7/site-
packages/sage/structure/coerce_maps.so in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3757)()
/mazur/release/merger/sage-5.12.beta4/local/lib/python2.7/site-
packages/sage/rings/finite_rings/finite_field_pari_ffelt.pyc in
_element_constructor_(self, x)
499 return x
500 else:
--> 501 return self.element_class(self, x)
502
503 def _coerce_map_from_(self, R):
/mazur/release/merger/sage-5.12.beta4/local/lib/python2.7/site-
packages/sage/rings/finite_rings/element_pari_ffelt.so in
sage.rings.finite_rings.element_pari_ffelt.FiniteFieldElement_pari_ffelt.__init__
(sage/rings/finite_rings/element_pari_ffelt.c:2975)()
/mazur/release/merger/sage-5.12.beta4/local/lib/python2.7/site-
packages/sage/rings/finite_rings/element_pari_ffelt.so in
sage.rings.finite_rings.element_pari_ffelt.FiniteFieldElement_pari_ffelt.construct_from
(sage/rings/finite_rings/element_pari_ffelt.c:3341)()
OverflowError: Python int too large to convert to C long
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/14888#comment:6>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/groups/opt_out.
