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I am using Octave for the first time today as a substitute to Matlab to try and call it from my Python script instead of using the matlab.engine. From what I've found, these two are compatible so running Matlab files in Octave is not complicated. However, one of my Matlab scripts contains the function "quadprog" which when invoked in my Octave command prompt yields the following error:

error: Invalid call to __qp__.  Correct usage is:

 -- [X, LAMBDA, INFO, ITER] = __qp__ (X0, H, Q, AEQ, BEQ, AIN, BIN,
          MAXIT, RTOL)
error: called from
    print_usage at line 98 column 5
    quadprog at line 352 column 36
    FRPY at line 606 column 14
    RPdriver at line 388 column 21
    my_VF_electrical_equivalent_circuit at line 119 column 23
    hi at line 60 column 49

How can I solve this problem? Also, I loaded the optim package in my Octave script.. to not avail, and when checking if it is already installed using this command pkg list, it is followed by an asterisk (as it happens optim*) what is this supposed to mean?

Regards.

Wallflower
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  • Please don't delete and ask the same question: https://stackoverflow.com/questions/65771742/using-matlabs-quadprog-in-octave Are these all your accounts? – Thomas Sablik Jan 18 '21 at 15:50
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    No that's not mine, but I was contacted by the person and as no one answered his question I tried to help but I did not find the answer. So I took it upon myself to rephrase it and post it on my account. Also, I may end up using Octave too so.. – Wallflower Jan 18 '21 at 20:43

1 Answers1

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The asterisk next to optim means that the package is properly loaded.

Obviously I cannot answer the other part of your question since there is no code. All I can tell you is that whatever it is you did resulted in an invalid call.

EDIT: I think I may have spotted a bug. Go to where you installed the optim package, and edit quadprog.m. Change line 353 from

__qp__ (x0, H, f, Aeq, beq, Ain, bin, maxit);

to

__qp__ (x0, H, f, Aeq, beq, Ain, bin, maxit, rtol);

and let me know if that magically makes it work.

It that's the case, I'll be reporting a bug to the octave/optim team.

EDIT 2: Turns out this is a known bug introduced in octave 6 which changed the function signature of the __qp__ function (called by quadprog.m). https://savannah.gnu.org/bugs/?59051

This has been fixed for the next release of the package; in the meantime you can just edit the code as above (the actual fix is a bit more elaborate for some reason).

Tasos Papastylianou
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