#9747: assigment to 1x1 submatrices specified by slices fails
---------------------------------+------------------------------------------
Reporter: phil | Owner: jason, was
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.5.3
Component: linear algebra | Keywords: matrix assignment slicing
__setitem__
Author: Philipp Schneider | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
---------------------------------+------------------------------------------
Changes (by phil):
* status: new => needs_review
Old description:
> Assigment to 1x1 submatrices specified by slices fails:
>
> == Example ==
> {{{
> ----------------------------------------------------------------------
> | Sage Version 4.5.2, Release Date: 2010-08-05 |
> | Type notebook() for the GUI, and license() for information. |
> ----------------------------------------------------------------------
> sage: A=matrix([[1,2],[3,4]])
> sage: B=matrix([[1,3],[5,7]])
> sage: A[1:2,1:2]=B[1:2,1:2]
> ---------------------------------------------------------------------------
> TypeError Traceback (most recent call
> last)
>
> /Users/phil/<ipython console> in <module>()
>
> /Applications/sage/local/lib/python2.6/site-
> packages/sage/matrix/matrix0.so in sage.matrix.matrix0.Matrix.__setitem__
> (sage/matrix/matrix0.c:5926)()
>
> /Applications/sage/local/lib/python2.6/site-
> packages/sage/matrix/matrix0.so in
> sage.matrix.matrix0.Matrix._coerce_element (sage/matrix/matrix0.c:7044)()
>
> /Applications/sage/local/lib/python2.6/site-
> packages/sage/structure/parent.so in
> sage.structure.parent.Parent.__call__ (sage/structure/parent.c:6407)()
>
> /Applications/sage/local/lib/python2.6/site-
> packages/sage/structure/coerce_maps.so in
> sage.structure.coerce_maps.DefaultConvertMap_unique._call_
> (sage/structure/coerce_maps.c:3108)()
>
> /Applications/sage/local/lib/python2.6/site-
> packages/sage/structure/coerce_maps.so in
> sage.structure.coerce_maps.DefaultConvertMap_unique._call_
> (sage/structure/coerce_maps.c:3010)()
>
> /Applications/sage/local/lib/python2.6/site-
> packages/sage/rings/integer.so in sage.rings.integer.Integer.__init__
> (sage/rings/integer.c:6807)()
>
> TypeError: unable to coerce <type
> 'sage.matrix.matrix_integer_dense.Matrix_integer_dense'> to an integer
>
> }}}
> The problem seems to be that the method !__setitem!__ treats 1x1
> submatices as elements of the rings over which the matrix is defined,
> while the method !__getitem!__ treats 1x1 submatices as 1x1 matrices.
>
> Below I will attach a patch which changes the method !__setitem!__ to
> treat 1x1 submatices specified by slices as 1x1 matrices.
New description:
Assignment to 1x1 submatrices specified by slices fails:
== Example ==
{{{
----------------------------------------------------------------------
| Sage Version 4.5.2, Release Date: 2010-08-05 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
sage: A=matrix([[1,2],[3,4]])
sage: B=matrix([[1,3],[5,7]])
sage: A[1:2,1:2]=B[1:2,1:2]
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/Users/phil/<ipython console> in <module>()
/Applications/sage/local/lib/python2.6/site-
packages/sage/matrix/matrix0.so in sage.matrix.matrix0.Matrix.__setitem__
(sage/matrix/matrix0.c:5926)()
/Applications/sage/local/lib/python2.6/site-
packages/sage/matrix/matrix0.so in
sage.matrix.matrix0.Matrix._coerce_element (sage/matrix/matrix0.c:7044)()
/Applications/sage/local/lib/python2.6/site-
packages/sage/structure/parent.so in sage.structure.parent.Parent.__call__
(sage/structure/parent.c:6407)()
/Applications/sage/local/lib/python2.6/site-
packages/sage/structure/coerce_maps.so in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3108)()
/Applications/sage/local/lib/python2.6/site-
packages/sage/structure/coerce_maps.so in
sage.structure.coerce_maps.DefaultConvertMap_unique._call_
(sage/structure/coerce_maps.c:3010)()
/Applications/sage/local/lib/python2.6/site-packages/sage/rings/integer.so
in sage.rings.integer.Integer.__init__ (sage/rings/integer.c:6807)()
TypeError: unable to coerce <type
'sage.matrix.matrix_integer_dense.Matrix_integer_dense'> to an integer
}}}
The problem seems to be that the method !__setitem!__ treats 1x1
submatices as elements of the rings over which the matrix is defined,
while the method !__getitem!__ treats 1x1 submatices as 1x1 matrices.
Below I will attach a patch which changes the method !__setitem!__ to
treat 1x1 submatices specified by slices as 1x1 matrices.
After applying the patch assignment to submatrixes specified by slices
works as expected:
== Example ==
{{{
sage: A=matrix([[1,2],[3,4]])
sage: B=matrix([[1,3],[5,7]])
sage: A[1:2,1:2]=B[1:2,1:2]
sage: A
[1 2]
[3 7]
}}}
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9747#comment:1>
Sage <http://www.sagemath.org>
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