i want to do non linear fitting using the function y=ae^(-bt) + C

I want to fit the non linear data using the function mentioned above. how do i get the values of a,b, & c. I have attached the text file which has my data.

Thank you.

Answer 1

[Nade Sritanyaratana]

Have you already parsed t and y from the text file?

I would suggest custom nonlinear fitting since it looks like you want to fit an exponential curve with a constant additive term. Here's a doc page about using CFTOOL to do this.

To do this programmatically, you can use a custom fit.

For example, for the function you are using, I would define a fittype like this:

f = fittype( @(a, b, C, t) a*exp(-b*t) + C);
coeffs = fit(t, y, f);
a = coeffs.a;
b = coeffs.b;
C = coeffs.C;

Make sure that t and y are column vectors. Good luck!

[Vinit]

Yes i have the t and y as separate cells

[Nade Sritanyaratana]

What do t and y look like? Can you print the output of both?

You will need to convert t and y to column vectors but the method to do so will depend on how they are currently stored.