#5256: [with patch, needs review] coherent handling of trivial matrices (depend
on
#5244, #5242).
----------------------------+-----------------------------------------------
Reporter: hivert | Owner: was
Type: defect | Status: new
Priority: critical | Milestone: sage-3.3
Component: linear algebra | Keywords: matrices, invert, determinant
----------------------------+-----------------------------------------------
There where a lot of inconsistency and bugs in the handling of trivial
matrices.
The following patch aims to solve these and to check systematicly the
coherence. Here is a selection of weirdness:
* plain wrong answers
{{{
sage: m = matrix(SR, 1,1, [1])
sage: m.inverse()
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
sage: m = matrix(RDF, 0,2)
sage: m.inverse()
[]
}}}
* Inconsistencies in the answers depending on the base ring
{{{
sage: m = matrix(RDF, 1,1)
sage: m.inverse()
---------------------------------------------------------------------------
LinAlgError Traceback (most recent call
last)
}}}
whereas
{{{
sage: m = matrix(QQ, 1,1)
sage: m.inverse()
---------------------------------------------------------------------------
ZeroDivisionError Traceback (most recent call
last)
}}}
Aside rewriting some error messages, changing some exception and working
around several bug in particular in maxima's handling of matrix over SR,
the main contribution of this patch lies in the function
{{{test_trivial_matrices_inverse}}} in {{{sage/matrix/matrix_space.py}}}
and its associated doctests. Trough a bunch of assertions this function
indirectly checks the behavior of matrix spaces. Any new implementation of
a kind of matrices should be checked be this function.
Patch Author: Florent Hivert
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5256>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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