A signal selecting means to which a plurality of signals of variable amplitude and sign are applied and which develops an output signal corresponding in magnitude and sign to preselected ones, depending on algebraic rank, of the midvalue applied signals, exclusive of the most algebraically positive and negative ones of the input signals. The output signal magnitude is controlled by a predetermined permutation of midvalue selections and in a manner that obviates transients on the output line as control is transferred to the various ones of the midvalue input signals.