The Green's function formalism is particularly applicable for problems where: (1) the domain is nearly infinite or, (2) when the linear response on selected boundary contours is sought given inhomogeneous Neumann conditions (or inversely). Typical problems that fall in this category are those of a plasma in contact with a resistive wall and the vacuum boundary condition computations in codes such as PEST and DCON. A code, GRIN, has been developed with similar capability to VACUUM, the code by Morrell Chance. Indeed GRIN borrows most of the ideas and algorithms pioneered by VACUUM. However, contrary to VACUUM, the code GRIN has a multilayer structure giving the user full control over the choice of Green's function and geometry while at the same time offering canned routines for ease-of-use. Accordingly, GRIN could be applied for problems outside plasma physics, such as electrostatics for instance. Although an early version of GRIN was written a few years ago, the code underwent a number of modifications and improvements as part of a summer student project. This talk will focus on these recent improvements, including a more accurate computation of the toroidal Laplace Green's function using the hypergeometric series and a new matrix/vector class based on the standard template library (STL), a recent addition to the C++ standard. The code is now configured to build on various architectures using autoconf, a tool that is widely employed in GNU projects. Comparisons with VACUUM will be shown.