[Octave-bug-tracker] [bug #60650] nmf_bpas from linear-algebra package fails for rank k=1

[Tasos Papastylianou]

URL:
  <https://savannah.gnu.org/bugs/?60650>

                 Summary: nmf_bpas from linear-algebra package fails for rank
k=1
                 Project: GNU Octave
            Submitted by: tpapastylianou
            Submitted on: Thu 20 May 2021 05:41:15 PM UTC
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Unexpected Error or Warning
                  Status: None
             Assigned to: None
         Originator Name: Tasos Papastylianou
        Originator Email: 
             Open/Closed: Open
                 Release: 6.2.0
         Discussion Lock: Any
        Operating System: Any

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Details:

To reproduce:


pkg load linear-algebra
V=rand(4, 20);
[w, h, i, s ]=nmf_bpas(V,1);


see https://stackoverflow.com/q/67618375/4183191 for context

I have narrowed down the culprit to line 373:


pGrad = [gradW(gradW<0|W>0); gradH(gradH<0|H>0)];


which should change to something like:


pGrad = [gradW(gradW<0|W>0); gradH(gradH<0|H>0)(:)];


This is because when the matrices involved are one-dimensional, logical
indexing may result in a horizontal vector instead of a vertical one, which
breaks the concatenation there.




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