• Source: Hyperrectangle

In geometry, a hyperrectangle (also called a box, hyperbox,



k


{\displaystyle k}

-cell or orthotope), is the generalization of a rectangle (a plane figure) and the rectangular cuboid (a solid figure) to higher dimensions. A necessary and sufficient condition is that it is congruent to the Cartesian product of finite intervals. This means that a



k


{\displaystyle k}

-dimensional rectangular solid has each of its edges equal to one of the closed intervals used in the definition. Every



k


{\displaystyle k}

-cell is compact.
If all of the edges are equal length, it is a hypercube. A hyperrectangle is a special case of a parallelotope.




Formal definition


For every integer



i


{\displaystyle i}

from



1


{\displaystyle 1}

to



k


{\displaystyle k}

, let




a

i




{\displaystyle a_{i}}

and




b

i




{\displaystyle b_{i}}

be real numbers such that




a

i


<

b

i




{\displaystyle a_{i}
. The set of all points



x
=
(

x

1


,
…
,

x

k


)


{\displaystyle x=(x_{1},\dots ,x_{k})}

in





R


k




{\displaystyle \mathbb {R} ^{k}}

whose coordinates satisfy the inequalities




a

i


≤

x

i


≤

b

i




{\displaystyle a_{i}\leq x_{i}\leq b_{i}}

is a



k


{\displaystyle k}

-cell.




Intuition


A



k


{\displaystyle k}

-cell of dimension



k
≤
3


{\displaystyle k\leq 3}

is especially simple. For example, a 1-cell is simply the interval



[
a
,
b
]


{\displaystyle [a,b]}

with



a
<
b


{\displaystyle a
. A 2-cell is the rectangle formed by the Cartesian product of two closed intervals, and a 3-cell is a rectangular solid.
The sides and edges of a



k


{\displaystyle k}

-cell need not be equal in (Euclidean) length; although the unit cube (which has boundaries of equal Euclidean length) is a 3-cell, the set of all 3-cells with equal-length edges is a strict subset of the set of all 3-cells.




Types


A four-dimensional orthotope is likely a hypercuboid.
The special case of an n-dimensional orthotope where all edges have equal length is the n-cube or hypercube.
By analogy, the term "hyperrectangle" can refer to Cartesian products of orthogonal intervals of other kinds, such as ranges of keys in database theory or ranges of integers, rather than real numbers.




Dual polytope



The dual polytope of an n-orthotope has been variously called a rectangular n-orthoplex, rhombic n-fusil, or n-lozenge. It is constructed by 2n points located in the center of the orthotope rectangular faces.
An n-fusil's Schläfli symbol can be represented by a sum of n orthogonal line segments: { } + { } + ... + { } or n{ }.
A 1-fusil is a line segment. A 2-fusil is a rhombus. Its plane cross selections in all pairs of axes are rhombi.




See also


Minimum bounding rectangle
Cuboid
Hilbert cube




Notes






References


Coxeter, Harold Scott MacDonald (1973). Regular Polytopes (3rd ed.). New York: Dover. pp. 122–123. ISBN 0-486-61480-8.




External links


Weisstein, Eric W. "Orthotope". MathWorld.
Foran, James (1991-01-07). Fundamentals of Real Analysis. CRC Press. ISBN 9780824784539. Retrieved 23 May 2014.
Rudin, Walter (1976). Principles of Mathematical Analysis. McGraw-Hill.

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