Iprev

Synopsis: iprev(integer) = integer

For the rotatable dihedral angle with the given index, between 1 and ndfree, this function returns the index of the rotatable dihedral angle that precedes it in the tree structure of dihedral angles. For the first rotatable dihedral angle, the function returns iprev(1) = 0.

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, ..