This software is written in Fortran 90 and is related to forward and inverse problems for the Helmholtz equation in 2-D.-This software is written in Fortran 90 and is related to forward and inverse problems for the Helmholtz equation in 2-D.

Eigenfunctions of integrable planar billiards are studied — in particular, the number of nodal domains, ν of the eigenfunctions with Dirichlet boundary conditions are considered. The billiards for which the time-independent Schrö dinger equ