8FUNCTIONS: idr - CYANA function

Synopsis: idr(<integer>) = <integer>

This function returns the residue index of the dihedral angle with
the given dihedral angle index.

The residues are indexed from 1 to nr according to the sequence
declared in the sequence file. The (external) residue number that
is used to identify a residue in the input files can be different
from the (internal) residue index. The function 'rnum' can be used
to obtain the external residue number of from the residue index.

Optionally, the <integer> dihedral angle index can be replaced by a
string consisting of the dihedral angle name and the residue number,
separated by a blank or a period, '.'.
