- Geodesic equation.
- Null congruences and optical scalars.
- Kinematics for time-like congruences.
- Ideal and spin fluid.
- Newman-Penrose formalism.
- Gravitational equations for the theory with arbitrary gravitational Lagrangian in Riemann and Riemann-Cartan spaces.

## Documentation
The detailed documentation including complete manual and short reference guide is provided.

- [Complete GRG Manual and Reference Guide](https://github.com/reduce-algebra/grg/tree/master/doc)

## Author

```text
Vadim V. Zhytnikov
Physics Department, Faculty of Mathematics,
Moscow State Pedagogical University,