Calling an imported variable into a function

I have imported a numerical matrix of size 336*1, and am trying to use it within a function. When i try to call it without any additional codes, it gives me a warning to ' Explicitly initialize the variable' and am not sure how to do that without passing it as a parameter in the function. I mainly don't want to pass it as a parameter as i am working with optimization and the non-linear constraints function works only with one variable inputy.

Do let me know how i could potentially call it within a function

[Stephen23]

"I mainly don't want to pass it as a parameter as i am working with optimization and the non-linear constraints function works only with one variable inputy"

That is exactly what function parameterization is for:

https://www.mathworks.com/help/matlab/math/parameterizing-functions.html

Simply add the required input arguments to your function definition, and then call it using an anonymous function, just like the documentation shows.

[Ebin Daniel]

I tried function parametrization however i got the following warning for the function below.

Unrecognized function or variable 'nlin'.

Error in test_4>nlinconst (line 80)

[c,ceq] = nlin(@const);

function [c,ceq] = nlinconst(C1Tin)

[c,ceq] = nlin(@const);

 function [c,ceq] = const(x)  
    
PolyCompEff = 0.85;
IsenExpo = 1.4;
PolyCompExpo = 1.503;
CompRatio = 8;
Cp_air = 1;
HxEff = 0.8;
WaterIn = 293.15;
Pch(1,1) = 2000;
Tch(1,1) = 400;
R = 0.287;
Vch = 10;

C1Tout(:,1) = C1Tin(:,1)*(CompRatio^(PolyCompExpo/(PolyCompExpo - 1)));
C2Tin(:,1) = WaterIn + HxEff*(WaterIn - C1Tout(:,1));
C2Tout(:,1) = C2Tin(:,1)*CompRatio^(PolyCompExpo/(PolyCompExpo - 1));
HXout(:,1) = WaterIn + HxEff*(WaterIn - C2Tout(:,1));

C1w(:,1) = (PolyCompEff^-1).*x(:,1).*Cp_air.*C1Tin.*(CompRatio^(PolyCompExpo/(PolyCompExpo - 1)) - 1);
C2w(:,1) = (PolyCompEff^-1).*x(:,1).*Cp_air.*C2Tin.*(CompRatio^(PolyCompExpo/(PolyCompExpo - 1)) - 1);

Mch(1,1) = IFChP*Vch/(R*Tch(1,1));

for i = 1:335
    Tch(i+1,1) = Tch(i,1) + (Mch(i,1)^-1).*(1-IsenExpo^-1).*(x(i,1).*HXout(i,1) - x(i,2).*Tch(i,1)).*1800;
    Pch(i+1,1) = (Mch(i,1) + (x(i,1) - x(i,2) ).*1800).*R.*x(i,1)./Vch;
    Mch(i+1,1) = Pch(i,1).*Vch./(R.*Tch(i,1));
end

  

c(:,1) = 700 - Pch(:,1);
c(:,2) = Pch(:,1) - 6464;
c(:,3) = C1w(:,1) - 18.6;
c(:,4) = C2w(:,1) - 18.6;
c(:,6) = Mch(:,1) - 350;


ceq(1,1) = 400 - Tch(1,1);
ceq(1,2) = 2000 - Pch(1,1);
ceq(336,2) = 2000 - Pch(336,1);


end

end

[Stephen23]

"Unrecognized function or variable 'nlin'."

That error message is quite clear: where is nlin defined? Why do you think that MATLAB should know what it is?