Rules for calculation of approximate value of definite integral

Abstract

We can calculate the definite integral exact value of f function with basic theorem of calculus which explains:If we can find an initial function for f .Despite all the conventional methods which exist for determining of initial function, we can find functions that are integrable in closed interval of   , a b , but there is no specified rule for them to determine an initial function.For example we consider the definite integral of, this integral exists but we can compute with classic rules.For approximate value determination these kinds of integrals there are some rules that we research three of them (trapezoid, Simpson, midpoint) in this article.