where rhs represents the right-hand side of the equation. The action of this statement is identical to the scaling carried out when computing the R value or the residual (cf. Eqs. 12.1, 12.6), except that it refers the scaling to the right-hand side of the equation, whereas in the residual or R value evaluation the scaling refers to . Therefore, if the right-hand side of the scaling operation consists of , the program refers only to but not to to .