Porting AHFinderDirect to a non-Cactus Numerical Relativity Code
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$Header$

As you almost certainly already know if you're reading this file,
AHFinderDirect is currently implemented as a thorn in the Cactus
computational toolkit.  However, AHFinderDirect is actually only
weakly coupled to the rest of Cactus, so it wouldn't be that hard
to port it to another (non-Cactus) numerical relativity code.  The
main requirements for such a port would be as follows:
* A Fortran 77 compiler, a C compiler, and a fairly modern
  (i.e. standards-compliant) C++ compiler.    
* A suitable geometry interpolator to do 3-D Hermite interpolation
  (across multiple processors if the new code is to be
  multiprocessor-capable).
* A suitable interpatch interpolator to do processor-local 1-D
  interpolation.  This interpolator must also be able to provide the
  Jacobian of the interpolation (i.e. the interpolation coefficients).
* If the new code is to be multiprocessor-capable, the routines used to
  broadcast status information to all processors, and to broadcast AH
  shapes to all processors for setting an excision mask, would need to
  be re-implemented.
* A few generic datatypes and low-level routines (for formatting and
  printing warning/error messages) would need to be re-implemented.