The Heaviside step function is a mathematical function denoted H(x), or sometimes theta(x) or u(x) (Abramowitz and Stegun 1972, p. 1020), and also known as the "unit step function." The term "Heaviside step function" and its symbol can represent either a piecewise constant function or a generalized function. When defined as a piecewise constant function, the Heaviside step function is given by H(x)={0 x<0; 1/2 x=0; 1 x>0 (1) (Abramowitz and Stegun 1972,...
