This is a small, untested C library w/o any error-checking features to manipulate Gaussian Cube Files -which is a chemical data format. Use at your own risk.
While code is not documented, yet, cube.h file may give you some idea of what
is there, and what is not.
There are also several examples using the library:
beautify.c : which tries to wrap back badly separated portions of, say, electron densities of a periodic image
interpolate.c : interpolates several images between two cube files, obtained for example from a MD simulation. Files needs to be in cube folder, and named as %d.cube.
qedat.c : reads Quantum Espresso cp.x dat files and writes cube files. Needs dat files named as dat/%d.dat with %d = nfi; cp.pos and an input file named cube.in
nat ntyp
num_of_atoms_type_i Z_i
Lattice parameters matrix, 3x3