bugGNU Octave - Bugs: bug #65704, (symbolic) element-wise power slow

 
 

bug #65704: (symbolic) element-wise power slow

Submitter:  None
Submitted:  Tue 07 May 2024 04:32:57 AM UTC
   
 
Category:  Octave Package Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Performance
Status:  Need Info Assigned to:  None
Originator Name:  Originator Email:  -email is unavailable-
Open/Closed:  * Open Release:  * 8.4.0
Operating System:  * Microsoft Windows Fixed Release:  None
Planned Release:  None
* Mandatory Fields

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Wed 08 May 2024 07:22:21 AM UTC, comment #3: 

That looks like it might be related to the symbolic package.
Consider reporting the issue to its maintainers:
https://github.com/gnu-octave/symbolic/issues

Markus M├╝tzel <mmuetzel>
Group administrator
Tue 07 May 2024 09:37:09 PM UTC, comment #2: 


f=sym([10 30 50 70 90])
pw=[1 1 1 1 0;1 1 1 0 1;1 1 0 1 1;1 0 1 1 1;0 1 1 1 1;1 1 1 0 0;1 1 0 1 0;1 1 0 0 1;1 0 1 1 0;1 0 1 0 1;1 0 0 1 1;0 1 1 1 0;0 1 1 0 1;0 1 0 1 1;0 0 1 1 1;1 1 0 0 0;1 0 1 0 0;1 0 0 1 0;1 0 0 0 1;0 1 1 0 0;0 1 0 1 0;0 1 0 0 1;0 0 1 1 0;0 0 1 0 1;0 0 0 1 1;1 0 0 0 0;0 1 0 0 0;0 0 1 0 0;0 0 0 1 0;0 0 0 0 1;0 0 0 0 0];
%% SHORT but SLOW
tic
for d=1:10
U=sum(prod(repmat(f,size(pw,1),1).^pw,2))
end
toc
%% LONG but FAST
tic
for d=1:10
  t=ones(sym([size(pw,1),1]));
  p=pw;
  for i=1:5
    while(any(p(:,i)))
      c=p(:,i) > 0;
      t(c)*=f(i);
      p(c,i)-=1;
    end
  end
  V=sum(t)
end
toc


Anonymous
Tue 07 May 2024 01:27:54 PM UTC, comment #1: 

We recognize that certain operations are faster, or more efficient than others. However, this may be but is not necessarily a bug in Octave.

Can you provide a specific code example of what you find concerning regarding relative computation speed? Is there a reason you think it is a bug in Octave causing that effect? It is unclear from the summary (hmst?)  what you are referring to.

Marking as Need Info for now, but we'll have to close this report as invalid without any clarifying information.

Nicholas Jankowski <nrjank>
Group Member
Tue 07 May 2024 04:32:57 AM UTC, original submission:  

Symbol power is very very slow. Multiplication is faster.

For test, count time for symbolic power and multiplication.

Anonymous

 

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    Follow 5 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2024-05-08 mmuetzel CategoryPerformance Octave Package
        Summaryhmst (symbolic) element-wise power slow
    2024-05-07 nrjank CategoryNone Performance
        Item GroupNone Performance
        StatusNone Need Info

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