Cactus Code Thorn PsiKadelia
Author(s)    : Steve Brandt
               John Baker
               Hisaaki Shinkai
               Paul Walker
Maintainer(s): Cactus team
Licence      : LGPL
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1. Purpose

This thorn provides a somewhat invariant means of measuring "waves" and 
other geometrical content in a numerically generated spacetime. 

Specifically, the thorn calculates the complex scalars psi0, psi1, psi2,
psi3 and psi4 with respect to a specified tetrad, and the invariants I 
and J.

If the tetrad has the right fall-off condition near infinity (the
"peeling property"), then the Weyl scalars psi have the following
meaning:

        Scalar  Falloff Physics
        -------------------------------------------------------------
        psi0    1/r     outgoing gravitational (transverse) radiation
        psi1    1/r^2   outgoing gauge (longitudinal) radiation
        psi2    1/r^3   static gravitational ("Coulomb") field
        psi3    1/r^4   ingoing gauge (longitudinal) radiation
        psi4    1/r^5   ingoing gravitational (transverse) radiation