is a basic function that turns True
. It is sometimes known as the characteristic function
or indicator function
It is often convenient to have functions with different forms in different regions. You can do this using Piecewise
Piecewise functions appear in systems where there is discrete switching between different domains. They are also at the core of many computational methods, including splines and finite elements. Special cases include such functions as Abs
handles piecewise functions in both symbolic and numerical situations.