Curious
Posts:
2,354
Registered:
12/6/04


Re: Numerical integration of polyfit coefficients
Posted:
Dec 12, 2013 1:52 PM


"Rajin " <patelr37@aston.ac.uk> wrote in message <l8ctcd$jrp$1@newscl01ah.mathworks.com>... > Hello, > > I have the coefficients of a polynomial of order 12 given to me using polyfit (it was fitted to model a probability density function). I now need to use the given polynomial f(x), multiply it by x^2, and integrate it over a given boundary. > > I have tried using the integral function: integral(fun,xmin,xmax), where: > fun = @(x) poly2sym(f) and f is the coefficients given by polyfit, but this doesn't work. > > Any ideas? Apologies if this seems trivial, I have tried everything! > > Thanks in advance, > Rajin
The obvious first question is: "What do you mean by doesn't work?" Any error message? Or just "looks" wrong.
It is not suprising you might get a nonsensical answer by trying to integrate a 12 order polynomial. Try a different fitting function.
Look at the MathWorks curve fitting toolbox or try ezyfit from the MATLAB FEX:
<<http://www.mathworks.com/matlabcentral/fileexchange/10176ezyfit241>>

