How do I curve fit the data set
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Prajwal Magadi
el 29 de Jul. de 2023
Comentada: Sam Chak
el 29 de Jul. de 2023
Hello all,
I'm facing difficulty in fitting the data.
The red ones are from the data set, and I want to fit that as like blue one (Experimental Data). How can I do that. I have also attached the data set for your reference.
Thank You.
2 comentarios
Sam Chak
el 29 de Jul. de 2023
Can you also suggest some candidate functions for fitting into the red data? Look up some Kernel functions.
Red data seems to have discontinuities at multiple intervals. Is it acceptable to have a piecewise function to fit the data?
Respuesta aceptada
Sam Chak
el 29 de Jul. de 2023
Not sure if this is what your want. But you can try finding the best math function to fit.
data = load('curve_fit.mat');
x = data.theta_degree';
y = data.x';
skewEqn = 'a/(sqrt(2*pi))*exp(- b*(x - c)^2)*((1/2)*(1 + erf(e*(x - c)/sqrt(2)))) + d';
fo = fitoptions('Method', 'NonlinearLeastSquares',...
'Lower', [ 0, 0, 5, 0, 0.1],... % {a, b, c, d, e}
'Upper', [100, 1, 20, 10, 1.0],...
'StartPoint', [50 0.5 10 5 0.5]);
ft = fittype(skewEqn, 'options', fo);
[yfit, gof] = fit(x, y, ft)
plot(yfit, x, y)
grid on, xlabel('\theta'), ylabel('x')
legend('Data', 'Fitted Skew Dist Fcn')
2 comentarios
Más respuestas (1)
Alex Sha
el 29 de Jul. de 2023
@Prajwal Magadi, one more function:
Sum Squared Error (SSE): 75571.6557870726
Root of Mean Square Error (RMSE): 2.74902993412354
Correlation Coef. (R): 0.962878352853849
R-Square: 0.927134722394541
Parameter Best Estimate
--------- -------------
y0 3.57509887406416
a 10210313.7484567
xc 17.1109591760412
w1 18.7010167618592
w2 -1.38399464317597
w3 -1.49504622174935
3 comentarios
Alex Sha
el 29 de Jul. de 2023
Hi, your data chart looks like peak-type function chart, so just try some typical peak functions, "Asym2Sig" function, shown above, gives more better outcomes.
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