Phi/psi to cartesian

[Mark Surles]

I want to generate an 'idealized' poly-alanine given a long series of
phi/psi angles.  I am looking for code, a code fragment, or algorithm
that will take a list of phi/psi angles, not necessarily repeating, and
produce cartesian coordinates of all the atoms.

This is not too hard, but my brain is not working tonight, and I'm sure
someone has done this already.

Thanks,

Mark Surles
surles at sdsc.edu
San Diego Supercomputer Center