Non-sinusoidal input

The previous calculations are based on a unit-amplitude sinusoidal input.

Non sinusoidal input to the waveshapping function produces less predictable output, and therefore is more difficult to keep alias free.

It is, however, possible to change the amplitude of the sinusoidal input so that it is less than--or greater than--1.

This creates a distortion index similar to the modulation index seen in FM synthesis.