My specific responsibility was the application of visualization and analysis techniques to verify and clarify the methodology of the calculations and their results. In order to experiment with the existing algorithm, I wrote an implementation in Igor which allowed far better visualization of the results than the existing workflow (Fortran generated binary running on a Unix workstation and providing risk contour plots).
Later I wrote a version in C which was about a 100 times faster on a modern pc than the Fortran code on the workstation.