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[Octave-bug-tracker] [bug #66514] spdiags does not "broadcast" elements
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From: |
Markus Mützel |
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Subject: |
[Octave-bug-tracker] [bug #66514] spdiags does not "broadcast" elements over selected diagonals |
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Date: |
Tue, 3 Dec 2024 07:35:41 -0500 (EST) |
Update of bug #66514 (group octave):
Status: None => Confirmed
Operating System: Microsoft Windows => Any
Summary: spdiags does not match one matlab on-line help
example => spdiags does not "broadcast" elements over selected diagonals
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Follow-up Comment #1:
The output of the original code snippet in Matlab R2024a:
>> n=9; A = spdiags ([1 2 3], -1:1, n, n); full (A)
ans =
2 3 0 0 0 0 0 0 0
1 2 3 0 0 0 0 0 0
0 1 2 3 0 0 0 0 0
0 0 1 2 3 0 0 0 0
0 0 0 1 2 3 0 0 0
0 0 0 0 1 2 3 0 0
0 0 0 0 0 1 2 3 0
0 0 0 0 0 0 1 2 3
0 0 0 0 0 0 0 1 2
>>
To put it in words: Matlab seems to "broadcast" elements of a row vector in
the first argument to the diagonals that are selected in the second argument
of `spdiag` if it is called with four input arguments.
Same for the three-input-argument form of `spdiag`.
In Matlab R2024a:
>> n=9; Z = sparse (n, n); A = spdiags ([1 2 3], -1:1, Z); full (A)
ans =
2 3 0 0 0 0 0 0 0
1 2 3 0 0 0 0 0 0
0 1 2 3 0 0 0 0 0
0 0 1 2 3 0 0 0 0
0 0 0 1 2 3 0 0 0
0 0 0 0 1 2 3 0 0
0 0 0 0 0 1 2 3 0
0 0 0 0 0 0 1 2 3
0 0 0 0 0 0 0 1 2
>>
Since this would change behavior of Octave, any change should go to the
default branch.
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Reply to this item at:
<https://savannah.gnu.org/bugs/?66514>
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