Find the boundaries of a convex set

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Description

Finds the boundaries of a bounded convex set along a specified straight line, using a bisection approach. It is mainly intended for use within arms.

Usage

1
convex.bounds(x, dir, indFunc, ..., tol=1e-07)

Arguments

x

a point within the set

dir

a vector specifying a direction

indFunc

indicator function of the set

...

parameters passed to indFunc

tol

tolerance

Details

Uses a bisection algorithm along a line having parametric representation x + t * dir.

Value

A vector ans of length two. The boundaries of the set are x + ans[1] * dir and x + ans[2] * dir.

Author(s)

Giovanni Petris GPetris@uark.edu

Examples

1
2
## boundaries of a unit circle
convex.bounds(c(0,0), c(1,1), indFunc=function(x) crossprod(x)<1)