Why does 'paretosearch' function show an error here?

I am getting an error : Unrecognized field name "nArchiveSize" , and I do not know how to fix it.

The 'optimoptions' is from plot-3-d-pareto-set.

'N3(x)' and 'N4(x)' are familer with 'N2(x)'.

function fa = N2(x)
u0=4*pi*1e-7;
eps0=1e-9/(36*pi);
fre = 0.9e9;
w = 2*pi*fre;
lamda = 3e8/fre;
k0 = w*sqrt(eps0*u0);

gamma1 = 0.63117783 - 1i*0.043092759;
gamma2 = gamma1*exp(2*1i*k0*lamda/4);
Zin1 = 376.99*(1 + gamma2)/(1 - gamma2);

x(:,6)=0;

d1 = x(:,1);
d2 = x(:,2);
d3 = x(:,3);
eps_r1 = x(:,4);
eps_r2 = x(:,5);
eps_r3 = x(:,6);
eps1 = eps_r1.*eps0;
eps2 = eps_r2.*eps0;
eps3 = eps_r3.*eps0;
k1 = w.*sqrt(eps1.*u0);
k2 = w.*sqrt(eps2.*u0);
k3 = w.*sqrt(eps3.*u0);
Z01 = sqrt(u0./eps1);
Z02 = sqrt(u0./eps2);
Z03 = sqrt(u0./eps3);

Zin2 = Z01.*(Zin1 + 1i.*Z01.*tan(k1.*d1))./(Z01 + 1i.*Zin1.*tan(k1.*d1));
Zin3 = Z02.*(Zin2 + 1i.*Z02.*tan(k2.*d2))./(Z02 + 1i.*Zin2.*tan(k2.*d2));
Zin4 = Z03.*(Zin3 + 1i.*Z03.*tan(k3.*d3))./(Z03 + 1i.*Zin3.*tan(k3.*d3));
gamma3 = (Zin4-377)./(Zin4+377);

aa = abs(imag(gamma3)); 
bb = abs(real(gamma3));
fa = aa+bb;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function F=fun(~)

F(1) = N2;
F(2) = N3;
F(3) = N4;

end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
clear
clc

fitnessfcn=@fun;

nvars=6;

lb=[0 0 0  1 1 1];
ub=[0.02 0.02 0.02  50 50 50];


A = [];
b = [];

Aeq=[];
beq=[];


options = optimoptions('paretosearch','UseVectorized',true,'ParetoSetSize',1,'PlotFcn','psplotparetof');


rng default

[x,fval]=paretosearch(fitnessfcn,nvars,A,b,Aeq,beq,lb,ub,[],options);

[PaulS]

Hi. Did you find the cause of this error? I'm getting the same error.

Answer 1

[ag]

Hi Kefeng,

I understand that you are facing the error "Unrecognized field name: nArchiveSize" while using the "paretosearch" function.

Upon debugging your code, I found that the objective function "N2", returns "NaN" value, which causes the function "initialize"(called through "paretosearch") to exit early, without initializing all the required variables. Therreafter, when the "nArchiveSize" is being accessed inside "driver"(called through "paretosearch"), which was never initialized, it throws the error.

The below lines from the function "N2", are producing "NaN" values, because of the "divide by zero" problem.

Z01 = sqrt(u0./eps1);
Z02 = sqrt(u0./eps2);
Z03 = sqrt(u0./eps3);
Zin2 = Z01.*(Zin1 + 1i.*Z01.*tan(k1.*d1))./(Z01 + 1i.*Zin1.*tan(k1.*d1));
Zin3 = Z02.*(Zin2 + 1i.*Z02.*tan(k2.*d2))./(Z02 + 1i.*Zin2.*tan(k2.*d2));
Zin4 = Z03.*(Zin3 + 1i.*Z03.*tan(k3.*d3))./(Z03 + 1i.*Zin3.*tan(k3.*d3));

To fix this, modify the logic for "N2", to get rid of the "divide by zero" scenario.

Please refer to the following documentation, for more details on creating an objective function:

https://www.mathworks.com/help/gads/computing-objective-functions.html

Hope this helps!

Best Regards,

Aryan Gupta