Variable
npi
The raised-index Newman-Penrose null tetrad. Computed by nptetrad
.
Defined as ug.np
. The product np.transpose(npi)
is constant:
(%i39) trigsimp(np.transpose(npi)); [ 0 - 1 0 0 ] [ ] [ - 1 0 0 0 ] (%o39) [ ] [ 0 0 0 1 ] [ ] [ 0 0 1 0 ]