How can I find and intersection values between line and polynomial equation ?
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Hi all,
First of all I have gathered some data from my experiments witch looks something like this:
Now I do a linearization for my data using Matlab command:
y=feval(fit(a(l:o,1,1),a(l:o,2,1),'poly1'),a(l:o,1,1));
Results looks like this:
Now I do a interpolation using for example 5th order poly and get this:
I calculate the peak value and calculate -3dB value of peak value and get a line as you can see in the image:
Now my question is, what is the fastest and the best function to find the intersection x values of the 5th order polynomial and the line?
3 Comments
Randy Souza
on 12 Apr 2013
Edited: Randy Souza
on 12 Apr 2013
<<image-url>>
I edited David's post to use the correct markup.
Answers (2)
Ryan Livingston
on 7 Mar 2013
Provided that you can evaluate the fit object like a function, I think you can but I'm not too familiar with those (they can be passed to FEVAL I think), you can write a small anonymous function like:
@(x)polyFun(x) - lineFun(x)
which evaluates the difference between the two, where "polyFun" returns the value of your 5th degree fit and "lineFun" returns the value of your line. Then that can be used in FZERO:
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