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Hi, I am trying to fit a function of the form: y = A0 + A1 * exp( -0.5* ( (X - Mu1) / Sigma1 )^2 ) - A2 * exp ( -0.5* ( (X-Mu2)/Sigma2 )^2 ) i.e. a mean term (A0) + a difference between two gaussians. The constraints are A1,A2 >0, Sigma1,Sigma2>0, and usually Sigma2>Sigma1. The plot looks like a "Mexican Hat". I had trouble (poor fits) fitting this function to toy data

Dear R-folks: I have a group of data ('x' and 'y' axis), but I'd like to know how to draw a graph which would fits my data in a better way, I also need its equation. Could you give me any R-rutine ideas?. I thank you in advance for your kind support. [[alternative HTML version deleted]]