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Re: Fitting a Complicated Function
Posted:
Jul 13, 2012 2:56 AM


.... Mathematica loves complex results, even when there is no need for it.
where are the data?
Peter
2012/7/10 <mpdgeorgin@gmail.com>: > I'm trying to fit a very complicated function and I'm having some problems. > > Right now I'm trying to do a Constrained fit where my parameters are R,m,a. > > FindFit[data, { > Exp[x/R] + > Exp[x/R]* > Sum[((a*x^(1  m))^n)* > Hypergeometric1F1[m*n, 1 + n  m*n, x/R]/ > Gamma[1 + n  m*n], {n, 1, 15}], 1 < R < 30, > 0 < a < .5, .4 < m < 1}, {R, m, a}, x] > > The error that appears is : > > Power:infy : infinite expression > FindFit:nrmnum : the function value Indeterminate is not a real number at{R,m,a} = {2, 0.94, 0.45} > > This is strange because I can evaluate the function at these values and it gives me a real, finite result. > > I have a couple questions: > > 1) Is there a way to check what the Find fit function is actually doing? As in can I look at the code to see exactly where its going wrong. > > 2) What should my next step be? according to my PI, simplification of the function doesn't lead anywhere. > > Thanks > > Marcel >



