What Does Nonlinearity Mean?
Nonlinearity is a term best understood by the definition of its opposite. Something that is linear can be expressed with a straight line. In mathematics, linear equations have certain qualities that nonlinear equations do not have. In the context of information technology, nonlinearity describes a system whose output does not vary in proportion to its input. Nonlinear systems are more of a challenge to control.
Techopedia Explains Nonlinearity
Perhaps a refresher in mathematics would help here. A linear equation can be represented on a graph using a straight line. The equation y = x + 1 would show a diagonal line where each point on the y axis has a value that is one unit higher than that point’s location on the x axis. Increasing the value on x by any number would have the same effect on y. Suppose the initial value of x is 1. Here are some examples of the proportional increase:
