Ifira

Synopsis: ifira(integer) = integer

The function returns the index of the first atom that belongs to the residue with the given index, or the special value ifira(nr+1) = na+1.

This function is useful, for instance, to construct a loop over all atoms of a given residue, i:

 do j ifira(i) ifira(i+1)-1
   print "Atom $anam(j) of residue $rnam(i) $rnum(i)"
 end do