[sage-support] Re: How to generate permutation matrices (fast)?

2020-11-23 Thread jplab
lundi 23 novembre 2020 à 14:44:00 UTC+1, jplab a écrit : > Hi all, > > I would have posted this question on AskSage, but I can't seem to be able > to connect through my google account (Authorization Error?). So I put the > question here. > > I would like to know how to iterat

[sage-support] How to generate permutation matrices (fast)?

2020-11-23 Thread jplab
Hi all, I would have posted this question on AskSage, but I can't seem to be able to connect through my google account (Authorization Error?). So I put the question here. I would like to know how to iterate through permutation matrices of a fixed size ($n\times n$) by breadth-first-search (by

[sage-support] Re: polyhedron H-representation: variables determined by equations

2019-09-01 Thread jplab
Hi Daniel, As far as I know, no such method is implemented in the polyhedron class. If I understood your situation, you want to know the set of coordinates "x_i" such that the projection along that axis is an injective function i.e. given a point in the image of the projection, you can lift it

Re: [sage-support] Re: Is this a bug in Polyhedron class (RDF vs AA)?

2015-10-13 Thread jplab
Hi, Thank you for your quick answer! Ok, that makes sense. I have a follow-up question. I will put it on sage-devel as it is related to the implementation of a ticket. Best, JP Le lundi 12 octobre 2015 22:21:12 UTC+2, vdelecroix a écrit : > > On 12/10/15 12:57, Nathann Cohen wrote: > >>

[sage-support] Is this a bug in Polyhedron class (RDF vs AA)?

2015-10-12 Thread jplab
Hi everyone, Is the following behavior normal: sage: P = polytopes.regular_polygon(5) sage: a_vertex = P.vertices()[0] sage: for facet in P.Hrepresentation(): print facet.contains(a_vertex), facet.interior_contains(a_vertex) True False True True True False True True True True sage: P =

[sage-support] sagesilent block in a newcommand macro

2012-01-16 Thread jplab
Hi everyone, I would like to include some nice tikz pictures of polytopes generated by sage (see http://trac.sagemath.org/sage_trac/ticket/12083 for the ticket.) in a tex file. But since I'm a lazy guy, I want tex to do the work for me. That's why I thought of a tex command that would: 1) take

[sage-support] Precision in (Real) Vector Space / Working with reflection groups

2011-01-26 Thread jplab
Hi! I am interested in computing orbits of vectors in a vector space using reflections. More specifically, the vector space is equipped with a inner product given by a certain Coxeter group (B_4 for those interested...). Then, I compute some image using my defined reflections operation. At some

[sage-support] Re: Precision in (Real) Vector Space / Working with reflection groups

2011-01-26 Thread jplab
On 26 jan, 12:47, D. S. McNeil dsm...@gmail.com wrote: (-6.66133814775094e-16, -1.00) ---??? Why isn't the first coordinate 0??? In theory it should be... Such things are basically inevitable with floating point whenever any number

[sage-support] Cosets representatives/Semi-direct product

2010-12-17 Thread jplab
Hi everyone, My question as two parts: First, I'm working with a group action on a set of objects and I would like to generate the orbit of an object. To simplify, we can think of the group acting on the set as a permutation group. Let G be the permutation group and H a subgroup of G.

[sage-support] Re: Runtime error: Unable to start gap (as user nobody with xgrid)

2010-02-11 Thread jplab
Hi, We switched to sage4.3.1 on all the machines, and it gives the same problem. I think it is related to this ticket: http://trac.sagemath.org/sage_trac/ticket/5965 Because, if we login with a local account on the machine, the command: sage: gap(2) 2 Works fine, But if we login with a

[sage-support] Runtime error: Unable to start gap (as user nobody with xgrid)

2010-02-01 Thread jplab
Hi, I'm currently using xgrid for my computations... Here is the setup: We have multiple imac OS 10.6, a intel server with mac OS 10.5 and two G5 mac (10.5). All of them have sage4.3 (or 4.3.1) binary build. In order for us to make xgrid work with sage, we gave some more rights for user nobody.

[sage-support] Re: Runtime error: Unable to start gap (as user nobody with xgrid)

2010-02-01 Thread jplab
Hi, On 1 fév, 14:01, Minh Nguyen nguyenmi...@gmail.com wrote: Hi, On Tue, Feb 2, 2010 at 5:29 AM, jplab jeanphilippela...@gmail.com wrote: SNIP My computation are considerably slowed down by this bug and I would be very happy to find a solution! Help! If you need more info, let me

[sage-support] Re: Runtime error: Unable to start gap (as user nobody with xgrid)

2010-02-01 Thread jplab
Greetings, On 1 fév, 14:44, Minh Nguyen nguyenmi...@gmail.com wrote: SNIP I think that is expected. The bug at http://trac.sagemath.org/sage_trac/ticket/7095 only affects Mac OS X 10.6. You should have no trouble using Sage 4.3 on Mac OS X 10.5. Oh, I see! Great! Thanks again! JP Labbé