Padding variable with LRSLib.generatorproducer

[matbesancon]

How to reproduce:

0 <= x1, x2 <= 1
x1 + x2 <= 1.5
x1 == x2

This yields the following polyhedron:

julia> poly = Polyhedra.polyhedron(m, LRSLib.Library())
Polyhedron LRSLib.Polyhedron:
1-element iterator of Polyhedra.HyperPlane{Rational{BigInt},Array{Rational{BigInt},1}}:
 HyperPlane(Rational{BigInt}[1//1, -1//1], 0//1),
5-element iterator of Polyhedra.HalfSpace{Rational{BigInt},Array{Rational{BigInt},1}}:
 HalfSpace(Rational{BigInt}[-1//1, 0//1], 0//1)
 HalfSpace(Rational{BigInt}[0//1, -1//1], 0//1)
 HalfSpace(Rational{BigInt}[1//1, 0//1], 1//1)
 HalfSpace(Rational{BigInt}[0//1, 1//1], 1//1)
 HalfSpace(Rational{BigInt}[1//1, 1//1], 3//2)

The vrep is all good:

julia> Polyhedra.vrep(poly)
V-representation Polyhedra.LiftedVRepresentation{Rational{BigInt},Array{Rational{BigInt},2}}:
2-element iterator of Array{Rational{BigInt},1}:
 Rational{BigInt}[3//4, 3//4]
 Rational{BigInt}[0//1, 0//1]

But the generator produces the following:

julia> chan = LRSLib.generatorproducer(hrep);

julia> collect(chan)
2-element Array{Any,1}:
 Rational{BigInt}[1//1, 3//4, 3//4]
 Rational{BigInt}[1//1, 0//1, 0//1]

It always adds an additional coordinate to the vertices, at the first position. Should this be documented?

[blegat]

Yes, this should be documented. Currently generatorproducer is only used internally.
LRSLib and CDDLib only support cones hence they lift polyhedra by adding an homogenizing variable. So for V-rep, 1 means it's a point and 0 means it's a ray.