The
multiple integral is a generalization of the
definite integral to
functions of more than one real
variable, for example,
f(
x,
y) or
f(
x,
y,
z). Integrals of a function of two variables over a region in
R2 are called double integrals, and integrals of a function of three variables over a region of
R3 are called triple integrals.