Cactus Code Thorn PsiKadelia
Authors    : Steve Brandt, John Baker, Hisaaki Shinkai, Paul Walker
CVS info   : $Header$
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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.