Here is a list of all documented modules with brief descriptions:

Ncstgeo	Constants for orientation and stretching of map
Ndcstgeo	Constants for orientation and stretching of map
Npesg	Suite of routines to perform the 2-parameter family of Extended Schmidt Gnomonic (ESG) regional grid mappings, and to optimize the the two parameters, A and K, of those mappings for a given rectangular domain's principal (median) semi-arcs with respect to a domain-averaged measure of distortion
Npfun	This module is for evaluating several useful real-valued functions that are not always available in Fortran compilers
Npietc	Some of the commonly used constants (pi etc) mainly for double-precision subroutines
Npkind	Standard integer, real, and complex single and double precision kinds
Npmat2	Routines dealing with the operations of banded matrices
Npmat4	Module for handy vector and matrix operations in Euclidean geometry
Npmat5	Utility routines for orienting the globe and basic geographical mappings
Npsym2	A suite of routines to perform the eigen-decomposition of symmetric 2*2 matrices and to deliver basic analytic functions, and the derivatives of these functions, of such matrices
Nutils	Module that contains general utility routines