FIG. 7 illustrates a graph 700 showing experimental results using the cubic function generator 600 as a shaper input to a power amplifier as in FIG. 2. For the experiment, the power amplifier produced an output signal related to the input signal substantially by 1/x.sup.3. The test was conducted using the setup of FIG. 2, with the function generator 220 being replaced by the specific cubic function generator 600. The graph 700 charts the input 210 on the horizontal axis 705 and the output 215 on the vertical axis 710. The cubic function generator 600 causes the output 215 of the power amplifier 205 to be approximately linear, as evidenced by output curve 720.