Using cell array of function handles as nonlinear constraints in fmincon

I have a cell array of function handles called Eqn, the unknown variable is called T. I want to use these function handles as my nonlinear equality constraints using fmincon.

I am calling my nonlinear constraint function like this:

nonlcon = @(T)EnergyBalance(T,Eqn);

The function is defined as:

function [c,ceq] = EnergyBalance(T,Eqn)
c = [];
ceq = Eqn;
end

When running I am getting the error "FMINCON requires all values returned by functions to be of data type double." which makes sense as ceq is a cell array. However I cannot convert ceq into a double as it contains multiple function handles.

So my question is: Is there a way to use a group of function handles stored in a cell array as the nonlinear constraints for fmincon?

[Torsten]

Does it suffice to evaluate them at T to get the correct double vector ceq ?

[Lennart Vogt]

Sorry, I am not sure what you mean by evaluating them at T

[Torsten]

One of the function handles could be

Eqn{1}=@(T)T-298

If the equality constraint would be T-298=0, you only had to evaluate Eqn{1} at T to get the correct ceq.

[Lennart Vogt]

How would you do that?

Defining ceq like

ceq = Eqn(T);

?

[Torsten]

ceq = Eqn{1}(T)

[Lennart Vogt]

I am getting "Not enough input arguments" for that line

[Torsten]

Eqn{1}=@(T)T-298;
T=14;
Eqn{1}(T)

[Lennart Vogt]

Well, T is the unknown vector I am searching for, so it is not sensible to assign a random value to it

[Torsten]

T is a numerical value handed to nonlcon, thus known during the evaluation of your function handles.

[Lennart Vogt]

Ok then T is not handed correctly atm. T is supposed to be the unknown vector I am searching for

[Torsten]

T is unknown, but a vector of doubles during the solution process, and your function handles have to be evaluated with this vector of doubles. T is not a vector of symbolic variables. I think you mix up symbolic with numerical computations.