half-space Green's function
...........................\bessel.f90
...........................\com_ptam.f90
...........................\comvar.f90
...........................\Gij_k.f90
...........................\green_derivatives_draw.m
...........................\green_draw.m
...........................\input.dat
...........................\main.f90
...........................\newfft.f90
...........................\nrtype.f90
...........................\nrutil.f90
...........................\ptam.f90