[Octave-bug-tracker] [bug #38954] kron product: output not sparse for diagonal input

[Carnë Draug]

URL:
  <http://savannah.gnu.org/bugs/?38954>

                 Summary: kron product: output not sparse for diagonal input
                 Project: GNU Octave
            Submitted by: carandraug
            Submitted on: Thu 09 May 2013 07:22:41 PM GMT
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.6.4
        Operating System: Any

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Details:

If any of the inputs in the kron function is sparse, the output should be
sparse as well. However, if the first input is not sparse AND comes from eye
() then it won't:


> issparse (kron (sparse (rand (5)), rand (5)))
ans = 1
> issparse (kron (rand (5), sparse (rand (5))))
ans = 1
> issparse (kron (sparse (rand (5)), eye (5)))
ans = 1
> issparse (kron (eye (5), sparse (rand (5))))
ans = 0





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