The Maple package NPTOOLS; a symbolic algebra package for tetrad formalisms in general relativity

In this paper, we present and discuss the NPTOOLS package written for the c omputer algebra system Maple. The package contains the main routines "nullt ran", "inv", "nullor", "ornull" and "pptype", The routine "nulltran" is an implementation of the 6-parameter Lorentz group in the Newman-Penrose (null tetrad) formalism, and "inv" checks for invariance of equations under subg roups of the Lorentz group. The routines "nullor" and "ornull" provide a tr anslation between the Newman-Penrose quantities associated with the null te trad and the orthonormal tetrad quantities associated with the Ellis-MacCal lum formalism. Finally, "pptype" determines the Petrov-Plebanski type of th e Ricci tensor. (C) 1998 Elsevier Science B.V.