title: Can I fit parameters of an arbitrary function of a single variable to data?
body: <p>I’m working in R.  I have a function (F) relating one variable (X) to another variable (Y).  (F) has 3 mutable parameters (A, B, C), such that Y == F(X) == G(X, A, B, C).  I would like to fit this function to a dataset which gives N (X, Y) pairs by finding the best (A, B, C).</p>
  
  <p>The relationship between (X) and (Y) is neither polynomial and nor some kind of probability distribution.  I'm curious if there's a way to do this for an arbitrary (F) as defined above.</p>