correct my integral in line43

please correct line 43 that is about integral function.

tnx a million.

clc;
clear;
close all;
% define sellmier equation to obtain refractive index
T=25; % tempreture in c
F = (T-24.5)*(T+570.5);
A1=4.5820; A2=0.09921; A3=0.21090; A4=0.021940; B1=5.2716E-8; B2=4.9143E-8; B3=2.2971E-7;
lambda_sh=0.775e-6; % SH wavelength
nlithium_sh = (sqrt(A1)+((A2+B1*F)/((lambda_sh^2)-(A3+B2*F)^2))+(B3*F)-(A4*(lambda_sh)^2));
lambda_ff=1.55e-6; % FF wavelength
nlithium_ff = (sqrt(A1)+((A2+B1*F)/((lambda_ff^2)-(A3+B2*F)^2))+(B3*F)-(A4*(lambda_ff)^2));
% parameters
k_sh=(2*pi/lambda_sh)*nlithium_sh;
k_ff=(2*pi/lambda_ff)*nlithium_ff;
capital_lambda = 20e-6;
Delta_kk = k_sh-2*k_ff;
l=pi/Delta_kk;   % for first order QPM
Delta_k=(Delta_kk-pi)/l;
lc = pi/Delta_kk;     % lc (coherence length);
L = 10e-3;            % Length;
N=L/(capital_lambda/2);    % number of domains
z=L;
% for d(z) as fourier serie
Km=2*pi/20e-6;
Gm=2/pi;
d33=27; % unit=pm/V
deff=(2/pi)*d33;
d0=(2/pi)*deff; % unit=pm/V
D=lc/capital_lambda;
% for SH field
syms z
GG = symsum(Gm * exp(1i * Km * z), 1, inf);
dz = GG * d0;  % periodic modulation
gzz = (pi/2*L)*(dz)/d0;
syms z
f = gzz * exp(1i * Delta_kk * z);
int(f,z,0,L);
y=int(f,z,0,L);
figure(1)
plot(y)
xlabel('Delta_k');
ylabel('SHG efficiency');

[Torsten]

GG is computed as Inf.

[Steven Lord]

What needs to be corrected in this context?

• Do you receive warning and/or error messages? If so the full and exact text of those messages (all the text displayed in orange and/or red in the Command Window) may be useful in determining what's going on and how to avoid the warning and/or error.
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• Did MATLAB crash? If so please send the crash log file (with a description of what you were running or doing in MATLAB when the crash occured) to Technical Support so we can investigate.

[asma]

this is my alarm.

Error using integral

First input argument must be a function handle.

Error in al (line 43)

integral(f,0,L);

GG value is inf. is it the reason that I achieve this alarm?

[Torsten]

I don't see that you use "integral" in your code.

[asma]

I difine f as a function and then i use int function (lines that I Bold them) that access in matlab.

[Torsten]

Yes, I see, but "int" is a symbolic integrator while "integral" is a numerical integrator - two different functions.

However: The problem with "int" comes from gzz which is Inf (because GG is Inf).

[asma]

tnx a million. as mathmatically Is it possible that we can get a Fourier integral from a Fourier series? i mean our function is a fourier series.

[Torsten]

A Fourier series with a constant coefficient Gm for all terms ? Usually, the Fourier coefficients converge to 0, don't they ?

[asma]

yes and the value of Gm is constant and is 0.63 .

i dont know about coefficients converge.

[Torsten]

https://math.stackexchange.com/questions/4166374/fourier-series-coefficients-converge-to-zero

It's impossible that GG is the Fourier series of any function.

I really don't understand what you are doing in your code.