Picard style iteration for anisotropic H-functions

An iterative approach is used to derive a 'closed form' approximation H* for Chandrasekhar's H-function in the general anisotropic case. Numerical results demonstrate a satisfactory accuracy level except in conservative or near conservative cases. Adjustments to H* are defined to improve accuracy where necessary. An outline is included on how emergent radiation may be represented either by extension of the iterative approach or by direct incorporation of H*