Here is one way:
In[1]:= (* make some data *)
data = Table[
rSquared = x^2 + y^2;
3. Exp[-rSquared/5^2],
{x, -10, 10}, {y, -10, 10}
];
In[2]:= (* generate an {x,y,z} list *)
indexedData =
Flatten[Table[{x, y, data[[x, y]]}, {x, Length[data]}, {y,
Length[data[[1]]]}], 1];
In[3]:= (* fit to Gaussian to recover parameters *)
FindFit[indexedData,
i0 Exp[-((x - x0)^2 + (y - y0)^2)/a^2], {i0, x0, y0, a}, {x, y}]
Out[3]= {i0 -> 3., x0 -> 11., y0 -> 11., a -> 5.}
