Solving Exponential equation with data
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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 个评论
Alex Sha
2020-9-11
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
Onkar Khadke
2020-9-11
采纳的回答
Alan Stevens
2020-9-10
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 个评论
Onkar Khadke
2020-9-11
Alan Stevens
2020-9-11
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.
Onkar Khadke
2020-9-11
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