Fitting an implicit nonlinear function

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Gian
Gian on 16 Oct 2015
Commented: Gian on 16 Oct 2015
I am trying to fit a function whose xData depends on a parameter of the fit.
More in detail: my x axis is given by x=x0+a/(1+C*x^2) where x0 is an array, C2 is a constant and a is the parameter of my fitting function. My y axis, instead, is fixed. Is there a way to do that? What I need to derive from that is the value of a.
Thak you all for the help

Answers (1)

John D'Errico
John D'Errico on 16 Oct 2015
If everything is known except for a, then what is the problem? I'll rewrite it to make it more clear.
x - X0 = a*(1./(1+C*x.^2)
So here from your comments, I assume we have multiple points in the form of values for x and X0, as well as a known value for C.
Solve the general problem
v = a*u
where u and v are vectors or matrices of the same size as simply
a = u(:)\v(:);
Apply the same approach to your problem.
  1 Comment
Gian
Gian on 16 Oct 2015
The problem is that I don't have x. I need to solve the equation (which depends on a) to find it.

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