清空筛选条件
清空筛选条件

Curve Fitting complex data (x,y) for constant extraction.

11 次查看（过去 30 天）
Gregory Manoukian
Gregory Manoukian 2023-7-17
回答： Lokesh about 10 hours 前
Ran in:
Hello,
I've been following the following link -- https://www.mathworks.com/help/optim/ug/fit-model-to-complex-data.html#
to try and extract the real constants (N_s,Tau_s, and c) from the Drude-Smith derivation for complex conductivity. This involves fitting both the real and imaginary components (which may be the problem in itself, since the example fits regular data with complex noise?)
I've attempted both lsqnonlin and lsqcurve fit methods.
file =['DSfit_Sitest.xls']; %%file attached
input = xlsread(file);
x = input(:,1); %%%% xdata, freqency, omega, real numbers from (0.2-1.4 THz)
R = input(:,2); %%%% Real component (blue in plot)
I = input(:,3);%%%% Imaginary component (orange in plot)
ydata = complex(R,I); %%%% complex conductivity, sigma_s
q = 1.602E-19; %% charge
m = 0.98; %% effective electron mass
mi = 1/0.98; %% inverse electron mass used to make typing the equation simpler
objfcn = @(C)(((C(1)*(q^2)*mi*C(2))./(1-1i.*x.*C(2))).*(1+(C(3)./(1-1i.*x.*C(2))))) - ydata;
opts = optimoptions(@lsqnonlin,'Display','off');
x0=[1e17, 100, -0.1]; %% initial guesses, I expect these to be reasonable values
LB = [1e15, 1, -1]; %%Typical carrier concentrations (cm-3), Tau_s (C(2)) units in picoseconds, -1<c<0
UB = [1e21, 1000, 0];
[const,~,residual,exitflag,output] = lsqnonlin(objfcn,x0,[],[],opts); %% does not run with LB and UB, so i leave blank.
This method outputs the initial guesses, and when I use the initial guesses to plot the outputs I get my data graph flipped, meaning my function just equals zero.
Using lsqcurvefit
objfcn = @(C,x)(((C(1)*(q^2).*mi.*C(2))./(1-1i.*x.*C(2))).*(1+(C(3)./(1-1i.*x.*C(2)))));
opts = optimoptions(@lsqcurvefit,opts);
x0=[1e17, 100, -0.1];
LB = [1e15, 1, -1];
UB = [1e21, 1e3, 0];
[constan,resnorm] = lsqcurvefit(objfcn,x0,x,ydata,[],[],opts)
constan = 1×3
1.0e+17 * 1.0000 0.0000 -0.0000
resnorm = 2.5565e+06
I get the error "not enough input arguments" in my objfcn, and it still outputs the initial guesses
Any help with why this isnt working or if im doing something really wrong is greatly appreciated! I am a novice Matlab user.
Thank you!!
  2 个评论
Image Analyst
Image Analyst 2023-7-17
Evidently it doesn't give that error when run here in MATLAB Answers. Attach ALL the red text so we can see which line of code is throwing the error.
Gregory Manoukian
Gregory Manoukian 2023-7-17
编辑：Gregory Manoukian 2023-7-17
"
Not enough input arguments
Error in CompCond_Si_Test_SimDS (line 140)
objfcn = @(C,x)(((C(1)*(q^2)*mi*C(2))./(1-1i.*x.*C(2))).*(1+(C(3)./(1-1i.*x.*C(2)))));
"
Sorry, I had put a cleaned up version of the code in my question, please note 'freqfit' = x for plots, i renamed it for simplicity of entering the function. Is it possible that the r2023 has changed so that the error doesnt appear? Thank you, please let me know if I can give any more information.

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Lokesh
Lokesh about 10 hours 前
Hi Gregory,
From the code attached in the comment, it seems that the error "not enough input arguments" arises due to the following line of code:
plot(freqfit, real(objfcn(constan)))
hold on
plot(freqfit, imag(objfcn(constan)))
Here, 'objfcn' is expecting two arguments, but only one argument 'constan' is being passed. If you intend to pass a second argument, which i assume to be 'x', the corrected code should be:
plot(freqfit, real(objfcn(constan,x)))
hold on
plot(freqfit, imag(objfcn(constan,x)))

类别

在 Help Center 和 File Exchange 中查找有关 Get Started with Curve Fitting Toolbox 的更多信息

标签

产品


版本

R2021b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by