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

Postby paulcheung » 06 Oct 2020, 03:50

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

Postby opfer » 06 Oct 2020, 09:59

It should be available through

Code: Select all

print $p->AFFINE_HULL;
Best regards,
Thomas

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

Re: Simple question regarding converting polytope to facets

Postby joswig » 06 Oct 2020, 11:20

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

Postby paulcheung » 08 Oct 2020, 16:37

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


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