Exponential sum models are used frequently: In heat diffusion, diffusion of chemical compounds, time series in medicine, economics and the physical sciences and technology.
Thus it is important to have good methods for estimation of parameters in exponential sums. The fitting of an exponential sum by e.g. a least squares criterion is difficult and good initial values are needed to help convergence.
The method of "Generalised Interpolation" (GI) will be presented as a tool for finding initial values. For one and two terms it gives a direct formula. For three and four terms it can be rewritten as an equation in one variable. For more than four terms (and also for three and four terms) it can be used to find a heuristic approach.