1. A method for modifying the values of select ones of a plurality of inputs to a plant, comprised of steps of: receiving the plurality of inputs; mapping in a first step of mapping N select ones of the received inputs through a first relationship defining P intermediate inputs numbering less than N, wherein the first relationship defines the relationship between the N select received inputs and the P intermediate inputs as a set of P intermediate values; processing the P intermediate values through a modifying process which modifies the P intermediate values in accordance with a predetermined modification algorithm to provide P modified intermediate inputs with corresponding P modified intermediate values; and mapping in a second step of mapping the P modified intermediate inputs and associated P modified intermediate values through the inverse of the first relationship to provide N modified select input values at the output of the second mapping step corresponding to the N select received input values.