How to Call a function inside for loop?

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Vaswati Biswas
Vaswati Biswas on 19 Nov 2021
Edited: Stephen23 on 19 Nov 2021
I am writing a function like this
function Eqn = eff(neff,hf)
nf=vpa(2.1511);
ns=vpa(1.5264);
nc=vpa(1.3354);
rho=1;
lambda=532.3;
Eqn = (((2*pi./lambda)*(sqrt(nf^2-neff.^2)*hf))-atan((nf/nc)^(2*rho)*sqrt ((neff.^2-nc^2)/(nf^2-neff.^2)))-atan((nf/ns)^(2*rho)*sqrt ((neff^2-ns^2)/(nf^2-neff.^2))) -(m*pi))==0;% equation 8 from paper
end
then I am calling it inside a for loop using the following code
hf = 75:20:350;
m= 0;
NEFF = zeros(size(hf));
for ii=1:numel(hf)
options = optimoptions('fsolve','Display','none','PlotFcn',@optimplotfirstorderopt);
neff = [0,5];
NEFF(ii)=fsolve(@(neff,hf(ii))eff(neff),neff,options
end
plot(hf, NEFF)
But I am getting an error
Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for
mismatched delimiters.
what mistake I am making here? Kindly help
  1 Comment
Stephen23
Stephen23 on 19 Nov 2021
Your code is missing severay parentheses and that anonymous function is not defined correctly.
Replace this
NEFF(ii)=fsolve(@(neff,hf(ii))eff(neff),neff,options
with something like
fnh = @(n)eff(n,hf(ii));
NEFF(ii) = fsolve(fnh,neff,options);
But I cannot run your code as the objective function needs to be debugged first.

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Answers (1)

Sulaymon Eshkabilov
Sulaymon Eshkabilov on 19 Nov 2021
Here is the corrected code, but still you should check the equation. The found roots are complex valued:
hf = 75:20:350;
NEFF = zeros(size(hf));
for ii=1:numel(hf)
options = optimoptions('fsolve','Display','none','PlotFcn',@optimplotfirstorderopt);
neff = [0; 5];
NEFF(ii)=fsolve(@(hf) eff(hf(ii), neff), neff,options);
end
%plot(hf, NEFF)
function F = eff(hf, neff)
nf=(2.1511);
ns=(1.5264);
nc=(1.3354);
rho=(1);
lambda=(532.3);
m=(0);
F = (((2*pi./lambda)*(sqrt(nf^2-neff.^2)*hf))-atan((nf/nc)^(2*rho)*sqrt ((neff.^2-nc^2)/(nf^2-neff.^2)))-atan((nf/ns)^(2*rho)*sqrt ((neff.^2-ns^2)/(nf^2-neff.^2))) -(m*pi));% equation 8 from paper
end
  1 Comment
Stephen23
Stephen23 on 19 Nov 2021
"Here is the corrected code.."
Note that this code completely ignores the values of hf defined on the first line. I doubt that is the intent.

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