How can i multiply each element of structured array

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NN
NN 2021-7-28
评论： NN 2021-8-2
I am trying to do an optimization problem in matlab.
below is the objective function .Here second and third term Price and Nb_dch1V, Price and Nb_ch1V are struct arrays (1 x 1 struct)
with two fields :
time 288 x 1 double
signal 1 x 1 struct
Signal again has two fields :
values 288 x 241 double
dimensions 241 .
hence is this objective function correct?
I am getting error
An error occurred while running the simulation and the simulation was terminated
Caused by:
  • Objective must be a scalar OptimizationExpression or a struct containing a scalar OptimizationExpression.
Please help
prob.Objective =dt*Price'*PbattupsV +dt*Price'*PbattdchV*Nb_dch1V'+ dt*Price'*PbattchV*Nb_ch1V' ;

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回答（2 个）

Alan Weiss
Alan Weiss 2021-7-28
编辑：Alan Weiss 2021-7-28
You need to extract the correct elements from your structures before using them. I am not sure what you mean to have as an objective. Maybe this:
var1 = dt*Price.time'*PbattupsV; % Check that this is a scalar expression
var2 = dt*Price.time'*PbattdchV*Nb_dch1V.time'; % Check that this is a scalar expression
var3 = dt*Price.time'*PbattchV*Nb_ch1V.time'; % Check that this is a scalar expression
prob.Objective = var1 + var2 + var3;
Alan Weiss
MATLAB mathematical toolbox documentation
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NN
NN 2021-7-28
and if i change Price.time to Price , it gives the same errror as before :
An error occurred while running the simulation and the simulation was terminated
Caused by:
  • Objective must be a scalar OptimizationExpression or a struct containing a scalar OptimizationExpression.
NN
NN 2021-7-29
编辑：NN 2021-7-29
I have tried this way also,
var2 = dt.*Price'.*PbattdchV;
var3 = dt.*Price'.*PbattchV;
prob.Objective =dt.*Price'.*PbattupsV+(var2.*Nb_dch1')+ (var3.*Nb_ch1');
but this gives the error :
An error occurred while running the simulation and the simulation was terminated
Caused by:
Argument dimensions 1-by-241 and 241-by-1 must agree.
Kindly advice

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Alan Weiss
Alan Weiss 2021-7-29
I'm sorry that you are having these problems, but you must realize that all of them are due to size mismatches in your structures. I am not sure why you are using structures; it might be easier if you simply used matrix variables.
In any case, if you have a 1-by-241 variable and a 241-by-1 variable that you are trying to add, then you should convert both to the same size. There are many ways of converting vectors. If M is the 1-by-241 variable, you can convert it to a 241-by-1 variable in any of the following ways:
M = M(:); % might be the best
M = M';
M = M.';
M = reshape(M,241,1);
M = reshape(M,[],1); % might be the best
M = reshape(M,[241,1]);
Use whichever you like.
Alan Weiss
MATLAB mathematical toolbox documentation
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Alan Weiss
Alan Weiss 2021-8-1
I suggest that you learn to use the debugger. Set a break point before you create prob.Objective. Carefully examine all your variables. The objective must be a scalar.
Alan Weiss
MATLAB mathematical toolbox documentation
NN
NN 2021-8-2
sure. will do that.Thank you very much for the support

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