def opbend_dist(rs, deriv=<NUM_LIT:0>):
return _opbend_transform(rs, _opdist_low, deriv)<EOL>
Compute the out-of-plane distance, i.e. the distance between atom rs[3] and plane rs[0],rs[1],rs[2]

       Arguments:
        | ``rs``  --  four numpy array with three elements
        | ``deriv``  --  the derivatives to be computed: 0, 1 or 2 [default=0]