chgcar is a small utility to +-/* CHGCAR type files. Especially suitable for large files, while it operates item by item. This is, however, it's biggest drawback: files only with the exactly same dimensions are allowed.

TODO: remove VASP nitems dependency

Usage: ./chgcar < input.chgcar

input.chgcar: 1.000 from.CHGCAR -1.000 this.CHGCAR diff.CHGCAR