Heaviside step function - Wikipedia
The Heaviside step function, or the unit step function, usually denoted by H or θ (but sometimes u, 1 or 𝟙), is a discontinuous function, named after Oliver Heaviside (1850–1925), whose value is zero for negative arguments and one for positive arguments. ():= {, <, ≥Where at 0 the value () = is chosen.. It is an example of the general class of step functions, all of which can be ...