GRG 3.2 Computer Algebra System for Differential Geometry, Gravitation and Field Theory. The computer algebra system GRG is designed to make calculation in differential geometry and field theory as simple and natural as possible. GRG is based on the computer algebra system Reduce but GRG has its own simple input language whose commands resemble short English phrases. GRG understands tensors, spinors, vectors, differential forms and knows all standard operations with these quantities. Input form for mathematical expressions is very close to traditional mathematical notation including Einstein summation rule. GRG knows covariant properties of the objects: one can easily raise and lower indices, compute covariant and Lie derivatives, perform coordinate and frame transformations etc. GRG works in any dimension and allows one to represent tensor quantities with respect to holonomic, orthogonal and even any other arbitrary frame. ...