The Heaviside function is the step function,

Regarding the value of Heaviside at , Maple implements the following convention: Heaviside(0) returns undefined and signals the invalid_operation numeric event. You can change this behavior by catching this event. For details, see NumericEvent and the Examples section below.

The Heaviside function is also the anti-derivative of Dirac in that

The Heaviside and Dirac functions are frequently used in the context of integral transforms, for example, laplace, mellin, or fourier, or in formulations involving differential equation solutions. These functions are also particularly relevant in Theoretical Physics, for example in Quantum Mechanics.

When converting Heaviside to piecewise you may want to have the conversion performed taking Heaviside(0) = 1. For that purpose set the Environment Variable _EnvUseHeavisideAsUnitStep to true - see the example in the next section.