# Collier's New Encyclopedia (1921)/Integral Calculus

**INTEGRAL CALCULUS**, a branch of
mathematics, the converse of the
differential calculus. Having a given or
known differential, the integral calculus
has for its object to find a function such
that, being differentiated, it will produce
the given differential. Such expression
is called the integral of the differential.
The operation of finding the primitive
function or integral is called integration.
Besides the method of finding the
integrals of given differentials, the integral
calculus is also applied to various
branches of mathematics, as well as to
almost every branch of natural philosophy
and engineering.