[Octave-bug-tracker] [bug #56037] qp exits with an indexing error for a specific input with OpenBLAS

[Mike Miller]

Follow-up Comment #19, bug #56037 (project octave):

I get the following three solutions with netlib, OpenBLAS, and ATLAS, now that
this patch is applied.

With OpenBLAS


x =

   0.12500
   0.00000
   0.00000
   0.66721
   0.00000
   0.00000
   0.10390
   0.10390

obj =  0.56250
info =

  scalar structure containing the fields:

    solveiter =  5
    info = 0



With netlib BLAS


x =

   0.12500
   0.23988
   0.00000
   0.00000
   0.00000
   0.00000
   0.00000
   0.63512

obj =  0.56250
info =

  scalar structure containing the fields:

    solveiter =  6
    info = 0



With ATLAS


x =

   0.12500
   0.23988
   0.00000
   0.00000
   0.00000
   0.00000
   0.00000
   0.63512

obj =  0.56250
info =

  scalar structure containing the fields:

    solveiter =  6
    info = 0



The difference between BLAS and OpenBLAS can also be seen by simply getting
the eigenvectors of the system. The different qp results are likely due
entirely to the different eigenvectors returned by the selected BLAS library.

With OpenBLAS


[v, ~] = eig (p)
v =

  -0.22089  -0.02616  -0.00000   0.16667   0.16667   0.83333  -0.27481 
-0.35355
   0.22089   0.02616   0.00000  -0.16667   0.83333   0.16667   0.27481  
0.35355
   0.22089   0.02616   0.00000   0.83333  -0.16667   0.16667   0.27481  
0.35355
   0.22089   0.02616   0.00000  -0.50000  -0.50000   0.50000   0.27481  
0.35355
  -0.11281   0.44394   0.70711  -0.00000  -0.00000   0.00000  -0.40643  
0.35355
  -0.11281   0.44394  -0.70711   0.00000   0.00000  -0.00000  -0.40643  
0.35355
  -0.85950  -0.26116   0.00000  -0.00000  -0.00000   0.00000   0.26086  
0.35355
   0.20156  -0.73136   0.00000   0.00000   0.00000   0.00000  -0.54725  
0.35355




[v, ~] = eig (p)
v =

  -0.07138   0.16667   0.16667   0.83333   0.22361   0.01465  -0.26399 
-0.35355
   0.07138   0.83333  -0.16667   0.16667  -0.22361  -0.01465   0.26399  
0.35355
   0.07138  -0.16667   0.83333   0.16667  -0.22361  -0.01465   0.26399  
0.35355
   0.07138  -0.50000  -0.50000   0.50000  -0.22361  -0.01465   0.26399  
0.35355
   0.07138  -0.00000  -0.00000   0.00000   0.89443  -0.01465   0.26399  
0.35355
  -0.45433  -0.00000  -0.00000   0.00000  -0.00000  -0.71838  -0.39053  
0.35355
  -0.56908   0.00000   0.00000  -0.00000   0.00000   0.68695  -0.28152  
0.35355
   0.66653   0.00000   0.00000   0.00000   0.00000   0.10468  -0.64791  
0.35355




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