GIMP :: Use Of Lens Distortion Filter? (2011)

I need to correct distortion from my 18-200 mm lens for my Nikon D80.

I can experiment with the controls until I get what looks reasonable,but it would be easier if I could find recommendations for settings of the lens distortion filter at different focal lengths for the lens.

I used to use a Panorama Tools plugin for gimp for which I found such recommendations, but I can't get that plugin to work with recent versions of gimp.

Of course I can experiment by photographing a grid at different focal lengths and different subject distances and using trial and error, and create my own tables.

Finally, where can I find a description of the the algorithm that the filter uses. If I had that, it might simplify things. Usually these algorithms apply a polynomial (usually cubic) correction based on the radial distance from the center of the image. The parameters set the coefficients of the polynomial.