Conversion to double from optim.prob​lemdef.Opt​imizationE​xpression is not possible.

Can anyone please help!!! I am trying to solve an optimization problem using MILP (problem-based approach)

'r' and 'q' are optimization variables

The following error occurred converting from optim.problemdef.OptimizationExpression to double: Conversion to double from optim.problemdef.OptimizationExpression is not possible.

How can I fix it????

nt = 24;
nh= 20;

Pbcd = 5*ones(nt,1);  
Eb = 5*ones(nt,1);
  Ebinv = (1/98)*ones(nt,1);

    Pbc = q.*Pbcd.*Ebinv;
    Pbd = r.*Pbcd.*Ebinv;

    socb = zeros(nt,1);
    socb(1,1) = 1;
    for i= 2:nt
        socb(i,1) = socb(i-1,1) + Pbc(i,1) - Pbd(i,1);
    end

[Matt J]

What line is the error occurring at?

[Sohaib Rafique]

Hi Matt,

Thanks for your response

The error is in 2nd last line

socb(i,1) = socb(i-1,1) + Pbc(i,1) - Pbd(i,1);

Before the 'end'

[natascia andrenacci]

I have the same error in a similar problem. Did you manage to solve it?

Answer 1

[Steven Lord]

Please add these lines immediately before the start of your for loop then run your code and show us what gets displayed. It will show us the types of your variables and make sure you haven't accidentally shadowed the built-in ones function with a version that performs some optimization calculations.

which -all ones
whos

[Sohaib Rafique]

This is what I got after running the code as suggested;

Error in MILP6 (line 133) socev(i,j) = socev(i-1,j) + o(i,j).*Pevcd(i,j).*Eevinv(i,j) - s(i,j).*Pevcd(i,j).*Eevinv(i,j);

built-in (C:\Program Files\MATLAB\R2017b\toolbox\matlab\elmat\ones) C:\Program Files\MATLAB\R2017b\toolbox\distcomp\parallel\@distributed\ones.m % Shadowed distributed method C:\Program Files\MATLAB\R2017b\toolbox\distcomp\parallel\@codistributor2dbc\ones.m % Shadowed codistributor2dbc method C:\Program Files\MATLAB\R2017b\toolbox\distcomp\parallel\@codistributor1d\ones.m % Shadowed codistributor1d method C:\Program Files\MATLAB\R2017b\toolbox\distcomp\parallel\@codistributed\ones.m % Shadowed codistributed method C:\Program Files\MATLAB\R2017b\toolbox\distcomp\gpu\@gpuArray\ones.m % Shadowed gpuArray method The following error occurred converting from optim.problemdef.OptimizationExpression to double: Conversion to double from optim.problemdef.OptimizationExpression is not possible.

Error in MILP6 (line 116) socb(i,1) = socb(i-1,1) + Pbc(i,1) - Pbd(i,1);

Name              Size            Bytes  Class                                      Attributes

Ba               24x1               192  double                                               
Bb               24x1               192  double                                               
Cbchr            24x1               464  optim.problemdef.OptimizationExpression              
Cbchrtotal        1x1               464  optim.problemdef.OptimizationExpression              
Cbdeg            24x1               464  optim.problemdef.OptimizationExpression              
Cbdegt           24x1               464  optim.problemdef.OptimizationExpression              
Cbdegtotal        1x1               464  optim.problemdef.OptimizationExpression              
Cbdis            24x1               464  optim.problemdef.OptimizationExpression              
Cbdistotal        1x1               464  optim.problemdef.OptimizationExpression              
Ceh              24x20             3840  double                                               
Cevceh           24x1               464  optim.problemdef.OptimizationExpression              
Cevchr           24x1               464  optim.problemdef.OptimizationExpression              
Cevchrtotal       1x1               464  optim.problemdef.OptimizationExpression              
Cevdeg           24x20              464  optim.problemdef.OptimizationExpression              
Cevdegt          24x1               464  optim.problemdef.OptimizationExpression              
Cevdegtotal       1x1               464  optim.problemdef.OptimizationExpression              
Cevdeh           24x1               464  optim.problemdef.OptimizationExpression              
Cevdis           24x1               464  optim.problemdef.OptimizationExpression              
Cevdistotal       1x1               464  optim.problemdef.OptimizationExpression              
Ch               24x1               192  double                                               
Chtotal           1x1                 8  double                                               
Cp               24x1               192  double                                               
Cpv              24x1               192  double                                               
Cpvtotal          1x1                 8  double                                               
Cs               24x1               192  double                                               
Db               24x1               192  double                                               
Dev              24x20             3840  double                                               
EVa              24x20             3840  double                                               
EVb              24x20             3840  double                                               
Eb               24x1               192  double                                               
Ebinv            24x1               192  double                                               
Eev              24x20             3840  double                                               
Eevinv           24x20             3840  double                                               
Pbc              24x1               464  optim.problemdef.OptimizationExpression              
Pbcd             24x1               192  double                                               
Pbchr            24x1               464  optim.problemdef.OptimizationExpression              
Pbchrt            1x1               464  optim.problemdef.OptimizationExpression              
Pbd              24x1               464  optim.problemdef.OptimizationExpression              
Pbdis            24x1               464  optim.problemdef.OptimizationExpression              
Pbdist            1x1               464  optim.problemdef.OptimizationExpression              
Pevc             24x20              464  optim.problemdef.OptimizationExpression              
Pevcd            24x20             3840  double                                               
Pevchr           24x1               464  optim.problemdef.OptimizationExpression              
Pevchrt           1x1               464  optim.problemdef.OptimizationExpression              
Pevd             24x20              464  optim.problemdef.OptimizationExpression              
Pevdis           24x1               464  optim.problemdef.OptimizationExpression              
Pevdist           1x1               464  optim.problemdef.OptimizationExpression              
Pgt               1x1               464  optim.problemdef.OptimizationExpression              
Ph               24x20             3840  double                                               
Pht               1x1                 8  double                                               
Phtt             24x1               192  double                                               
Ppv              24x1               192  double                                               
Ppvt              1x1                 8  double                                               
a                24x20             3840  double                                               
expr             24x1               192  double                                               
i                 1x1                 8  double                                               
j                 1x1                 8  double                                               
nh                1x1                 8  double                                               
nt                1x1                 8  double                                               
o                24x20                8  optim.problemdef.OptimizationVariable                
p                 1x1                24  optim.problemdef.OptimizationProblem                 
q                24x1                 8  optim.problemdef.OptimizationVariable                
r                24x1                 8  optim.problemdef.OptimizationVariable                
rq               24x1               464  optim.problemdef.OptimizationExpression              
s                24x20                8  optim.problemdef.OptimizationVariable                
so               24x20              464  optim.problemdef.OptimizationExpression              
socb             24x1               192  double                                               
socbmax           1x1                 8  double                                               
socbmin           1x1                 8  double                                               
socev            24x20             3840  double                                               
socevmax          1x1                 8  double                                               
socevmin          1x1                 8  double

[Sohaib Rafique]

In addition, 'r' and 'q' are optimization variables Type - integer Lower bound - 0 Upper bound - 1

Answer 2

[Alan Weiss]

If you intend socb to be an optimization expression, then initialize it that way.

socb = optimexpr(nt,1); % Not zeros(nt,1)
socb(1,1) = 1;

Alan Weiss

MATLAB mathematical toolbox documentation

[Sohaib Rafique]

Hi Alan

Thanjs for your help I made the suggested changes but it didn't work