Hi,

I am looking to fit a set of data with the following exponential.

y = a + b*exp(-x/c) + (d*x/c)*exp(-x/c) with x>0.

So i would like to find the best four values for the parameters a to d.

I am trying to work out something with a least squares method but I am not sure how to start (problems with how to weight y). Does anyone have an idea here?

Any answer would be highly appreciated!