Simple question regarding converting polytope to facets

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paulcheung
Posts: 11
Joined: 06 Oct 2020, 03:45

Simple question regarding converting polytope to facets

Hi all, I have a simple question regarding the function. I have the following code

$p = new Polytope(POINTS=>[[1,1,1],[1,1,0]]); print$p->FACES;

The result prints:

0 0 1
1 0 -1

It stands for $1\geq x_2$, $x_2 \geq 0$. Yet, where is the condition $x_1=1$? I was hoping to get

-1 1 0
1 -1 0
0 0 1
1 0 -1

Yet, it isn't the case. Why? Can anyone help me with this? Thank you!

opfer
Developer
Posts: 80
Joined: 04 Feb 2013, 11:12

Re: Simple question regarding converting polytope to facets

It should be available through

Code: Select all

print \$p->AFFINE_HULL;
Best regards,
Thomas

joswig
Main Author
Posts: 267
Joined: 24 Dec 2010, 11:10

Re: Simple question regarding converting polytope to facets

Yes, inequalities and equalities are kept seperate. You can use them in the way you described as input (by specifying INEQUALITIES and maybe EQUATIONS), but FACETS and AFFINE_HULL give irredundant output.

paulcheung
Posts: 11
Joined: 06 Oct 2020, 03:45

Re: Simple question regarding converting polytope to facets

Thank you for all the replies! I got it now.