#7989: Minpoly doesn't work for all matrices
------------------------------+---------------------------------------------
Reporter: jason | Owner: was
Type: defect | Status: needs_work
Priority: major | Milestone: sage-4.7.1
Component: linear algebra | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author: Jason Grout
Merged: | Dependencies:
------------------------------+---------------------------------------------
Comment(by was):
This is a great patch. I can't believe this has got ignored for the last
1.5 years.
Regarding what needs to be fixed, the test failure you claim for
matrix_integer_2x2 is:
{{{
deep:sage wstein$ sage -t matrix/matrix_integer_2x2.pyx
sage -t "matrix/matrix_integer_2x2.pyx"
**********************************************************************
File "/Users/wstein/sage/install/sage-4.7.1.rc0/devel/sage-
main/sage/matrix/matrix_integer_2x2.pyx", line 101:
sage: TestSuite(m).run()
Expected nothing
Got:
Failure in _test_minpoly:
Traceback (most recent call last):
File "/Users/wstein/sage/install/current/local/lib/python/site-
packages/sage/misc/sage_unittest.py", line 275, in run
test_method(tester = tester)
File "matrix2.pyx", line 1302, in
sage.matrix.matrix2.Matrix._test_minpoly (sage/matrix/matrix2.c:8933)
File "polynomial_element.pyx", line 358, in
sage.rings.polynomial.polynomial_element.Polynomial.subs
(sage/rings/polynomial/polynomial_element.c:5624)
File "polynomial_element.pyx", line 557, in
sage.rings.polynomial.polynomial_element.Polynomial.__call__
(sage/rings/polynomial/polynomial_element.c:5819)
File "polynomial_element.pyx", line 638, in
sage.rings.polynomial.polynomial_element.Polynomial.__call__
(sage/rings/polynomial/polynomial_element.c:7244)
File "element.pyx", line 1302, in
sage.structure.element.RingElement.__add__
(sage/structure/element.c:11504)
File "coerce.pyx", line 766, in
sage.structure.coerce.CoercionModel_cache_maps.bin_op
(sage/structure/coerce.c:7337)
TypeError: unsupported operand parent(s) for '+': 'Space of 2x2
integer matrices' and 'Integer Ring'
------------------------------------------------------------
The following tests failed: _test_minpoly
**********************************************************************
1 items had failures:
1 of 6 in __main__.example_7
***Test Failed*** 1 failures.
For whitespace errors, see the file
/Users/wstein/.sage//tmp/.doctest_matrix_integer_2x2.py
[4.6 s]
}}}
This is because substitution isn't even implemented for that class:
{{{
sage: MS = sage.matrix.matrix_integer_2x2.MatrixSpace_ZZ_2x2()
sage: a = MS([1,2,3,4])
sage: a.minpoly()
x^2 - 5*x - 2
sage: a.minpoly()(a)
---------------------------------------------------------------------------
TypeError
}}}
Also, if one adds this for minpoly, it would make sense to also add
_test_charpoly.
-- William
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7989#comment:6>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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