I'm interested in an algorithm (or source code, any language) for calculating the pole locations for a Gaussian to 6db or Gaussian to 12 db filter. I have sources that provide the pole locations, and software applications that calculate the pole locations, but I need the algorithm. I suspect that it's done by some kind of successive approximation, but I'm not sure.
You are right. I have never seen a closed form mathematical equation for determining the pole locations in any filter book. You will have to do a solving routine that changes the pole locations to produce the prescribed results with an error function as the item to be minimized.