Opened 8 years ago

Last modified 6 years ago

#13611 new defect

block_matrix forgets subdivisions of submatrices

Reported by: jsrn Owned by: jason, was
Priority: minor Milestone: sage-6.4
Component: linear algebra Keywords: block_matrix
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Description

Writing the following

m = matrix(ZZ,2,2, [1,2,3,4])
M=block_matrix([m,m],nrows=1)
block_matrix([M,M],ncols=1)

should return the same as

m = matrix(ZZ,2,2, [1,2,3,4])
block_matrix([m,m,m,m],nrows=2)

However, the former forgets the subdivided structure of M when constructing the second block-matrix.

The above will not be possible in cases where the sub-sub-divisions do not line up, but in cases where it is, there seems to be no reason to throw away this information. In particular, it makes block_matrix much more useful for iteratively constructing a large matrix while still retaining the most detailed level of sub-divisions (since there is no notion of multi-level sub-divisions).

Change History (5)

comment:1 Changed 7 years ago by kcrisman

Maybe for a different ticket...

A = matrix([[1,2],[4,2]])
B = block_matrix([ [1, A], [0, 1] ])
B+B; B*B

Neither seems to "preserve" the block structure.

comment:2 Changed 7 years ago by jdemeyer

  • Milestone changed from sage-5.11 to sage-5.12

comment:3 Changed 6 years ago by vbraun_spam

  • Milestone changed from sage-6.1 to sage-6.2

comment:4 Changed 6 years ago by vbraun_spam

  • Milestone changed from sage-6.2 to sage-6.3

comment:5 Changed 6 years ago by vbraun_spam

  • Milestone changed from sage-6.3 to sage-6.4
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