I was working for Dr. Alexander Pletzer as a scientific programmer trainee on the GRIN package in July, August and September 2001 at the Princeton Plasma Physics Laboratory in the Computational Plasma Physics Group.

From the GRIN's web page: GRIN is a package to solve elliptic problems in two dimensions using Green's functions. The advantage of the Green's function formalism compared to a finite element approach for instance, is that one is left with a lower dimensional problem, namely the one of computing line integral in two-dimensions. Because the Green's functions can be chosen so as to vanish at infinity, this formalism is particularly applicable to problems where the domain is large or extends to infinity. Another typical application of the Green's function formalism is when one is only interested in determining the field on selected contours.

My contributions to the package include:

- designing and implementing C++ classes based on the Standard Template Library to represent matrices and vectors,
- improving the accuracy and performance of the hypergeometric function evaluation,
- improving the cubic spline class,
- testing GRIN against a Mathematica code,
- applying Autoconf to build on many UNIX platforms.

You can download the package from the NTCC Library. You can get a presentation about GRIN here.