Maxima Function
nptetrad ()
Computes a Newman-Penrose null tetrad (np
) and its raised-index
counterpart (npi
). See for an example.
The null tetrad is constructed on the assumption that a four-diemensional orthonormal frame metric with metric signature (-,+,+,+) is being used. The components of the null tetrad are related to the inverse frame matrix as follows: