Solving Exponential equation with data
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Onkar Khadke
il 10 Set 2020
Commentato: Onkar Khadke
il 11 Set 2020
Dear sir,
I want to find four unknowns(a,b,c,d) which would fit with the model as y = a*(1-exp(-b*x)) + c*(exp(d*x)-1).
I am attaching data herewith. Please help me in chosing initial guess for unknowns.
Please provide steps and code in case for me to get started and able to fit it with the model.
Thank you
2 Commenti
Alex Sha
il 11 Set 2020
1:
a -0.00353320943950358
b -0.00183821185934112
c -0.0092638389118119
d -0.00950908245890883
2:
a 0.00926383877006205
b 0.00950908267448672
c 0.00353320959565315
d 0.0018382118314121
Risposta accettata
Alan Stevens
il 10 Set 2020
Try
a = 0.0093; b = 0.0095; c = 0.0035; d = 0.00185;
f = a*(1 - exp(-b*x)) + c*(exp(d*x) - 1);
plot(x,y,'o',x,f),grid
xlabel('x'),ylabel('y')
legend('data','function')
to get
However, the curve fitting toolbox shoud get an even better fit (I don't have the curve fitting toolbox, so did a rough fit outside of Matlab).
3 Commenti
Alan Stevens
il 11 Set 2020
As I said, because I don't have MATLAB's curve fitting toolbox I used another piece of software (Mathcad) to do the fit. I then rounded the numbers to the values I listed in my earlier reply.
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