In three dimensions, a parallelepiped is a prism whose faces are all parallelograms. Let ,
,
and
be the basis vectors defining a three-dimensional parallelepiped. Then the parallelepiped
has volume given by the scalar
triple product
(1)
| |||
(2)
| |||
(3)
|
In
dimensions, a parallelepiped is the polytope spanned
by
vectors
, ...,
in a vector space over the
reals,
(4)
|
where
for
,
...,
.
In the usual interpretation, the vector space is
taken as Euclidean space, and the content
of this parallelepiped is given by
(5)
|
where the sign of the determinant is taken to be the "orientation" of the "oriented volume" of the parallelepiped.
Given
vectors
,
...,
in
-dimensional
space, their convex hull (along with the zero
vector)
(6)
|
is called a parallelepiped, generalizing the notion of a parallelogram, or rather its interior, in the plane. If the number of vectors is equal to the dimension, then
(7)
|
is a square matrix, and the volume of the parallelepiped is given by ,
where the columns of
are given by the vectors
. More generally, a parallelepiped has
dimensional volume given by
.
When the vectors are tangent vectors, then the parallelepiped represents an infinitesimal -dimensional volume element.
Integrating this volume can give formulas for the volumes of
-dimensional objects in
-dimensional space. More intrinsically, the parallelepiped
corresponds to a decomposable element of the exterior algebra
.