Obtaining the multiple Debever null directions

Abstract The explicit expression of the multiple Debever null directions of an algebraically special spacetime are obtained in terms of the electric and magnetic parts of the Weyl tensor. An algorithm for the determination of the Petrov-Bel type and the algorithm to obtain the multiple Debever null directions are implemented as functions of a new package of xAct , a Mathematica suite of packages for tensor manipulations. These functions are applied to two examples.