Before revision: We obtain our output signal, , by passing our input through a non-linear function : will contain the three frequencies of the input signal, , , and (which are known as the fundamental frequencies), as well as a number of linear combinations of the fundamental frequencies, each of the form where , , and are arbitrary integers which can assume positive or negative values.
After revision: We obtain our output signal, , by passing our input through a non-linear function : will contain the three frequencies in the input signal, , , and (which are known as the fundamental frequencies), as well as a number of linear combinations of the fundamental frequencies, each of the form where , , and are arbitrary integers which can assume positive or negative values.