Sum of Optimization Variables NOT working

Hi, I am trying to find the sum of an optimization variable. However I am getting no output when the optimization variable contains quadratic terms. For exmaple, if I try to find the sum of an optimization array containing terms such as:

6.19*power(1, 'P_1') + 17.26*power(1, 'P_2') + 16.6*power(1, 'P_3') + 16.5*power(1, 'P_4') + 19.7*power(1, 'P_5') ...

I am able to find the sum.

However, when the array contains terms such as:

0.00048*power(1, 'P_1')^2 + 0.00031*power(1, 'P_2')^2 + 0.002*power(1, 'P_3')^2 + 0.00211*power(1, 'P_4')^2 + 0.00398*power(1, 'P_5')^2 + .........

And I attempt to find the sum, I dont get an output. Neither do I get an error message. The "ans" variable is empty.

Any help is greatly appreciated.

[Walter Roberson]

Could you post some sample code?

[Micah Mungal]

The problem lies with the "powerCost1" variable. "diag_quadcost" contains terms of this form:

0.00048*power(1, 'P_1')^2 + 0.00031*power(1, 'P_2')^2 + 0.002*power(1, 'P_3')^2 + 0.00211*power(1, 'P_4')^2 + 0.00398*power(1, 'P_5')^2 + .........

The "powerCost2" variable however contains the sum of terms of the following form:

6.19*power(1, 'P_1') + 17.26*power(1, 'P_2') + 16.6*power(1, 'P_3') + 16.5*power(1, 'P_4') + 19.7*power(1, 'P_5') ...

And I can find the sum of terms of this form.

But without the "powerCost1" the simulation cannot be completed.

[Walter Roberson]

When you talk about getting no output, is that from the call to cplexmiqp()? That is a third party toolbox from IBM.

[Micah Mungal]

No I am talking about this line: powerCost1 = sum(diag_quadcost, 1). This is where I get no output.

When I run the code, I got an error related to CPLEX. So I rechecked my code for errors and came across a problem with the powerCost1 variable. Although "diag_quadcost" is an array of optimization expression, when I try to find this sum of this array, I get no output. I'm assuming that because "powerCost1" has no output, the objective function will not be properly defined in the first place for CPLEX to work.

[Walter Roberson]

Which MATLAB release are you using?

We might need a copy of the xlsx files, just in case the problem is data-specific somehow.

[Micah Mungal]

I have noticed however, that I can find the sum of optimization expressions when there are no quadratic terms. This is the case for the powerCost2 variable where temp_powerCost2 is also an array of optimization expression but with NO quadratic terms. I only get the problem for powerCost1 where the optimization expressions in diag_quadcost contains quadratic terms. Not sure if this is some limitation of MATLAB?

Answer 1

[Micah Mungal]

Solved the problem. Taken from:

https://www.mathworks.com/help/optim/ug/optimization-expressions.html