[Ifeffit] Generating single scattering paths in Artemis

[Matt Newville]

Hi Carlo,

Yep, I know about and have played with F2PY.  For Ifeffit I use
SWIG because I also need to be able to call Ifeffit from other
C-based languages.

The issue for Feff is that it is not itself suitable for calling
in any manner except as a full application.  The Feff6 code is not
modular in any sense of the word, and relies heavily on common
blocks.  Also, a Feff6 calculation cannot be stopped in the middle
and restarted reliably (despite what the "CONTROL" cards might
imply, if feff.inp changes during a run of Feff6 the results are
not easily predictable).  The upshot is that it would take an
enormous amount of work (including getting rid of many of the
common blocks) to do any better than
  os.system("feff6")

Anyway, that's all a separate topic....

--Matt