<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2012) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2012) (Learn how and when to remove this template message) </Td> </Tr> <P> 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 argument and one for positive argument . It is an example of the general class of step functions, all of which can be represented as linear combinations of translations of this one . </P> <P> The function was originally developed in operational calculus for the solution of differential equations, where it represents a signal that switches on at a specified time and stays switched on indefinitely . Oliver Heaviside, who developed the operational calculus as a tool in the analysis of telegraphic communications, represented the function as 1 . </P>

What is the integral of unit step function