How to apply custom equation on a curve and find unknown parameter
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I've a curve and I've to apply following custom equation and have to find the unknown parameters A and B
y=3.379-(A*X^2/(B+X))
please guide me how can I do this operation.
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Answers (2)
Andreas Goser
on 8 Mar 2011
When you write "I have a curve", I assume you have data. Make sure the data X and y is in your MATLAB workspace.
Start CFTOOL
Import the data (DATA button)
Use the FITTING button and choose customer equiation as TYPE OF FIT
2 Comments
Andreas Goser
on 8 Mar 2011
True. Here an overview over multiple options with MATLAB: <http://www.mathworks.com/support/tech-notes/1500/1508.html>
But I'd say CFTOOL is the absolute easiest way for a new user to do fitting.
Matt Tearle
on 8 Mar 2011
f = @(b,x) 3.379 - (b(1)*x.^2./(b(2)+x))
bfit = nlinfit(xdata,ydata,f,b0)
where xdata and ydata are your data values to fit to, and b0 is an initial guess for the parameters
2 Comments
Walter Roberson
on 25 Jul 2019
In this b0 would be a vector of length 2 of numeric values, which will serve as initial guess for the search.
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