# crossPolytope -- computes the d-dimensional crosspolytope with diameter 2s

## Synopsis

• Usage:
P = crossPolytope(d,s)
• Inputs:
• d, an integer, strictly positive
• s, ZZ or QQ, positive (optional)
• Outputs:

## Description

The d-dimensional crossPolytope with diameter s is the convex hull of +/- s times the standard basis in QQ^d. If s is omitted it is set to 1.

 i1 : P = crossPolytope(3,3/2) o1 = P o1 : Polyhedron i2 : vertices P o2 = | -3/2 3/2 0 0 0 0 | | 0 0 -3/2 3/2 0 0 | | 0 0 0 0 -3/2 3/2 | 3 6 o2 : Matrix QQ <--- QQ

## Ways to use crossPolytope :

• "crossPolytope(ZZ)"
• "crossPolytope(ZZ,QQ)"
• "crossPolytope(ZZ,ZZ)"

## For the programmer

The object crossPolytope is .