How can I change the output of the code to scalar?

I am trying to find the optimal values of a function @poweroptone but the GA tool doesn't complete the optimization because of the vector error. To be precise, this is the error that pops up `Error running optimization. Your fitness function must return a scalar value.` Here is the code:

 function Pmax = poweroptone(Lt, R)
Lt =(0.01:0.0005:0.07);
R=(4:0.025:7);
Pmax =((1222.714521).*sqrt(Lt).*sqrt(0.03 + Lt./2).*sqrt(R./(R - 1)).*((sqrt(0.27) - 1.054.*sqrt(0.03 + Lt))./(sqrt(0.27).*(sqrt(0.03 - Lt)))));
end

The number of variables are two (2). How can I change the output of the code to scalar?

[Adam]

Why are you overwriting your two input arguments at the start of the function?

At a glance, if Lt and R are non-scalar though then Pmax will necessarily also be non-scalar and of the same size as Lt and R (which I would assume need to be the same size as each other)

[Stephen23]

function Pmax = poweroptone(Lt, R)
Lt =(0.01:0.0005:0.07);
R=(4:0.025:7);

Your function's input arguments are ignored because you redefine them immediately on the first two lines, so ga cannot optimize anything anyway.

The output needs to be a single scalar value. Your code currently outputs a 1x121 numeric vector (not a scalar).

"How can I change the output of the code to scalar?"

Only you can answer this, because it depends on the meaning of those values and what property you are trying to optimize. For example summing them, taking the maximum, minimum, mean, median, or finding the RMS value, or any of the other infinite possible functions that convert 121 values into 1 value. Some of them might make sense, or perhaps none of them. What are you trying to optimize?

[Peter Mwangi]

Thank you. Then what should I do to fix the problem?

[Peter Mwangi]

I am trying to find the minimum value of Pmax for specific one value pf Lt and R

Answer 1

[Peter Mwangi]

Thank you for the feedback. I found the solution to the question. I first created the objective function

function P = power_one(x)

P=(1222.714521).*(sqrt(x(1))*sqrt(0.03 + (x(1))/2)*sqrt ((x(2))/((x(2) - 1)))*((sqrt(0.27) - 1.054 * sqrt(0.03 + x(1)))/(sqrt(0.27)*sqrt(0.03 + x(1)))));

end

And then I called it in the main function as follows;

Lb=[0.01 4];

Ub=[0.07 7];

fitn =@(x)power_one(x);

[x, fval]=ga(fitn,2, [], [], [], [], Lb, Ub);

I hope this will help someone in future. Thank you for the input.