Hi,

As

**Sean **correctly pointed out, if you know the model and want to find model parameters for it, then

**FindFit[] **is for you.

Here is an example:

(* test function *)

f[x_] := 5. Exp[-0.98 x] + 3. Exp[-1.34 x];

(* plot it *)

Plot[f[x], {x, 0, 3}, PlotRange -> All]

(* data *)

data = Table[{x, f[x]}, {x, 0, 3, 0.01}];

(* find fit *)

FindFit[data, a Exp[b x] + d Exp[c x], {a, b, c, d}, x]

I.M.