createBoundBox: Calculate a bounding box

In hitandrun: "Hit and Run" and "Shake and Bake" for Sampling Uniformly from Convex Shapes

Calculate a bounding box

Description

Calculate a bounding box around a polytope given by a set of linear constraints.

Usage

createBoundBox(constr, homogeneous=FALSE)

Arguments

constr	Constraint definition
homogeneous	Whether constr is given in homogeneous coordinate representation

Details

See har for a description of the constraint definition and the homogeneous coordinate representation.

This function uses findExtremePoints to find extreme points along each dimension.

Value

lb	Lower bound for each dimension (not including homogeneous coordinate).
ub	Upper bound for each dimension (not including homogeneous coordinate).

Author(s)

Gert van Valkenhoef

See Also

har

findExtremePoints

Examples

# constraints: x_1 >= 0, x_2 >= 0, x_1 + x_2 <= 1
A <- rbind(c(-1, 0), c(0, -1), c(1, 1))
b <- c(0, 0, 1)
d <- c("<=", "<=", "<=")
constr <- list(constr=A, rhs=b, dir=d)

bb <- createBoundBox(constr)
stopifnot(bb$lb == c(0.0, 0.0))
stopifnot(bb$ub == c(1.0, 1.0))

hitandrun documentation built on May 28, 2022, 1:09 a.m.