MATLAB: Function inside function using lsqcurvefit

curve fittinglsqcurvefitoptimization

Hello,
I want to fit the curve of the TL function to the xn_fft function and find the design variables x []. Notice that the TL function contains several functions. The code gives:
{Index exceeds matrix dimensions. Error in optimization (line 34). Ln1=x(1);Ln2=x(2); % necks length }
Any help is welcome and appreciated!
clear all;clc;
%% Harmonic sine waves
fs = 400;     % Sampling rate [Hz]
Ts = 1/fs;     % Sampling period [s]
fNy = fs / 2;  % Nyquist frequency [Hz]
duration = 0.5; % Duration [s]
t = 0 : Ts : duration-Ts; % Time vector
noSamples = length(t);    % Number of samples
f = 0 : fs/noSamples : fs - fs/noSamples; % Frequency vector
fundamental_signal = 1.5.*sin(2 .* pi .* 50 .* t); %Fundamental signal
First_Harmonic = 1.5.*sin(2 .* pi .* 100 .* t);     %FH1=100 Hz %First Harmonic
Total_signal = fundamental_signal + First_Harmonic; % Contaminated signal
xn_fft = abs(fft(Total_signal)); % FFT
%% TL for 2-DOF HR
c=340.3;   % Speed of sound in the air
w=2*pi()*f;
density=1.225;   % Air density
Sd=4.3*4.3e-4;  % duct area
Lv1=2.5e-3;Lv2=2.5e-3; %length of the cicular cavities
%Variables
x=[ ];
Ln1=x(1);Ln2=x(2);                      % necks length
S1=x(3); S2=x(4);   % necks area

V1=x(5);  V2=x(6);    % Cavities volume
Rn1= (S1/(pi()))^0.5; Rn2= (S2/(pi()))^0.5; % necks area
Rv1=((V1/(pi()))^0.5)/0.05; Rv2=((V2/(pi()))^0.5)/0.05;
% Calculations
% Effective neck length
correc_n1d=0.82*(Rn1/2);
correc_n1v1=0.85*Rn1*(1-(1.25*(Rn1/Rv1)));
correc_n2v1=0.85*Rn2*(1-(1.25*(Rn2/Rv1)));
correc_n2v2=0.85*Rn2*(1-(1.25*(Rn2/Rv2)));
Leff1=Ln1+correc_n1d+correc_n1v1;
Leff2=Ln2+correc_n2v1+correc_n2v2;
%Mass
M1=density.*S1.*Leff1;
M2=density.*S2.*Leff2;
%Matrix element
a11=((-M1*(w.^2))+((density.*c^2.*(S1)^2)./V1));
a12=((-density.*(c^2).*S1.*S2)./V1);
a21=((-density.*(c^2).*S1.*S2)./V1);
a22=(-M2.*(w.^2))+((density.*(c^2)*((S2)^2)*((1./V1)+(1./V2))));
%Results
Z=(((a11.*a22)-(a12.*a21))./(a22.*density.*c.*S1.*w.*1i));
TL=20.*log10(abs(1+(S1./(2.*Sd.*Z))));
%% Optimization function
lb=[10e-5,10e-5,10e-5,10e-5,10e-5,10e-5]; ub=[1,1,1,1,1,1]; x0=(lb+ub)/2; 
fun = @(x,f) 20.*log10(abs(1+(x(3)./(2.*Sd.*Z))));
x = lsqcurvefit(fun,x0,f,xn_fft,lb,ub)
plot(f,xn_fft,'ko',f,fun(x,f),'b-')
xlim([0 fNy]); xlabel('Frequency (Hz)'); ylabel('Transmission Loss (dB)');

Best Answer

clear all;clc;
Okay, so this is a script, not a function.
x=[ ];
Ln1=x(1);Ln2=x(2);                      % necks length
S1=x(3); S2=x(4);   % necks area
V1=x(5);  V2=x(6);    % Cavities volume
You initialize x to empty, and then try to use 6 values out of it.
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