#8276: Make the one(), identity_matrix() and zero_matrix() cached and immutable.
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Reporter: hivert | Owner: hivert
Type: defect | Status: new
Priority: major | Milestone: sage-4.3.3
Component: algebra | Keywords: One mutable.
Author: Florent Hivert | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Description changed by hivert:
Old description:
> {{{
> sage: A = MatrixSpace(ZZ, 3)
> sage: A.one()
> [1 0 0]
> [0 1 0]
> [0 0 1]
> sage: A.one()[1,2] = 1
> sage: A.one()
> [1 0 0]
> [0 1 1]
> [0 0 1]
> }}}
> Indeed it is mutable an cached !
New description:
After I found the following bug, it was decided on sage-devel that in a
{{{MatrixSpace}}} the methods {{{.one()}}}, {{{.identity_matrix()}}} and
{{{.zero_matrix()}}} should returns a cached immutable matrix. I had to
update sage's library accordingly.
{{{
sage: A = MatrixSpace(ZZ, 3)
sage: A.one()
[1 0 0]
[0 1 0]
[0 0 1]
sage: A.one()[1,2] = 1
sage: A.one()
[1 0 0]
[0 1 1]
[0 0 1]
}}}
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8276#comment:1>
Sage <http://www.sagemath.org>
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