Advanced radiation

Files in d_earth/d_opt/d_rad with the subroutines or functions which they contain

1. gxs2sr.for, for surface-to-surface radiation
   • gxs2sr
2. gx2dvf.for
   • gx2dvf computes 1D and 2D view factors
   • gspect
   • gband
   • coatng
   • gaussj
3. gximsl.for, the coding which provides the IMMERSOL model
   • gximsl
   • gxabsr