how to increase 'MaxFunEvals'

Question

柊介小山内 2022-12-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1881047-how-to-increase-maxfunevals

评论： Torsten 2022-12-19

I want to increase 'maxFunEvals' in my program, but it doesn't work. What is the problem of my program?

clear all;
a = 0.2;      %field loss coefficient α[db/km]
alfa = a*log(20)/20;
gamma = 1.3;       % fiber non-linearity coefficient　
Ns = 20;        %number of span
Ls = 100;       %span length[km]         
beta2 = 20.7;     %dispersion coefficient[ps^2/km]
roll = 0.3; %roll-off of gwdm
%% formula of　ρ
syms f f1 f2 real %f,f1,f2 is THz
Le = (1-exp(-2*alfa*Ls))/(2*alfa);
x1(f1,f2,f) = 1-exp(-2*alfa*Ls)*exp(4j*(pi^2)*(f1-f)*(f2-f)*beta2*Ls);%symfun
x2(f1,f2,f) = 2*alfa-(4j*(pi^2)*(f1-f)*(f2-f)*beta2);
p(f1,f2,f) = Le^(-2)*(abs(x1(f1,f2,f)/x2(f1,f2,f)))^2;
%% formula of Gwdm
syms t w k 
T=1/(32e-3);
A = pi*t/T;
x(t)= (sin(A)/A)*(cos(roll*A)/(1-(2*roll*t/T)^2));
X(w) = simplify(fourier(rewrite(x(t),'exp'),t,w));
X(f) =X(2*sym(pi)*f);
X(f)= rewrite(abs(X(f)),'sqrt');
xfunc = matlabFunction(X(f));%@(f)
GWDM(f)= (symsum(xfunc(f+(50e-3)*k),k,-5,5)/((32/8.8)*T));
func = p*GWDM(f1)*GWDM(f2)*GWDM(f1+f2-f);
ft=matlabFunction(func);
%% formula of GNLI
pint = @(f)integral2(@(f1,f2)ft(f1,f2,f),-270.8e-3,270.8e-3,-270.8e-3,270.8e-3,'MaxFunEvals',20000);
NLI = @(f)(16/27).*Ns.^1.03.*gamma.^2.*Le.^2.*pint(f); % NLI
%f = -0.3:0.005:0.3;
%plot(f,arrayfun(@(f)NLI(f),f));
%hold on
%plot(f,GWDM(f));
%hold off

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柊介小山内 2022-12-19

编辑：柊介小山内 2022-12-19

在 MATLAB Online 中打开

Sorry my program was wrong. if you fix formula of GNLI in my code as below, warning message 'you have reached the maxmum number of function evaluations(10000). the result didn't pass global error test.' will display. I think this warning can solve by increasing MaxFunEvals. but I can't increase the value.

pint = @(f)integral2(@(f1,f2)ft(f1,f2,f),-270.8e-3,270.8e-3,-270.8e-3,270.8e-3);
NLI = @(f)(16/27).*Ns.^1.03.*gamma.^2.*Le.^2.*pint(f); % NLI
NLI(0.165)

I tried to increase value as below, but didn't increase.

options = optimset('MaxFunEvals',20000);
pint =@(f)integral2(@(f1,f2)ft(f1,f2,f),-270.8e-3,270.8e-3,-270.8e-3,270.8e-3);
NLI = @(f)(16/27).*Ns.^1.03.*gamma.^2.*Le.^2.*pint(f); % NLI
fminsearch(NLI,0.165,options);

Torsten 2022-12-19

I suggest you plot NLI for reasonable values of f to see how the function behaves.

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Answer 1

Matt J 2022-12-19

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1881047-how-to-increase-maxfunevals#answer_1131382

编辑：Matt J 2022-12-19

The problem is that integral2 does not support an option called 'MaxFunEvals'. You imagined somehow that it does.

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Matt J 2022-12-19

编辑：Matt J 2022-12-19

在 MATLAB Online 中打开

pint = @(f)integral2(@(f1,f2)ft(f1,f2,f),-270.8e-3,270.8e-3,-270.8e-3,270.8e-3,...
                     'AbsTol',1e-7);
NLI = @(f)(16/27).*Ns.^1.03.*gamma.^2.*Le.^2.*pint(f); % NLI
NLI(0.165)
ans = 0.0037