How to apply custom equation on a curve and find unknown parameter

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Abdul Samad
Abdul Samad 2011-3-8
评论： Walter Roberson 2019-7-25
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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回答（2 个）

Andreas Goser
Andreas Goser 2011-3-8
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 个评论
Andreas Goser
Andreas Goser 2011-3-8
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.

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Matt Tearle
Matt Tearle 2011-3-8
If you have Statistics Toolbox, use nlinfit.
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

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