Cutom Curve Fit for mixed plot

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Birsen Ayaz-Maierhafer
Birsen Ayaz-Maierhafer on 17 Jan 2022
Answered: Abhiroop Rastogi on 23 Feb 2022
Hi, I am trying to fit a custom equation to my data. Using cuve fitting tool box the closest was exp1 fit but it is still not a good fit. I tried the other available fits as well and it did not turned out good. As you see from the attached file at the beginning it is a linear , in the middle it is like exp and at the end it is different than linear and exp fit.
What are your recommendation as an equation to fit that curve.
Thank you
  3 Comments
Sam Chak
Sam Chak on 18 Jan 2022
Looks like it is plotted on a logarithmic scale. Since the exponential decay model does not fit, and you don't know the process (can be static or dynamic) that creates the data, then you can try the following:
The above suggestions may not solve your problem, but they are based on my experience with certain functions that display the asymptotic convergence behavior.

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Answers (1)

Abhiroop Rastogi
Abhiroop Rastogi on 23 Feb 2022
Hi Birsen,
The data shown in the figure looks like it is representing a Weibull Distribution. You can try the inbuilt fittype "weibull" for fitting the curve using the command:
fitCurve = fit(xData,yData,'weibull');
Another fit-type that can be used for the data is "cubicspline" which does a piecewise computation for fitting the curve.
You can use the following command for cubicspline fitting.
fitCurve = fit(xData,yData,'cubicspline');
You can see the resulted plots in the figures attached.

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