Le dimanche 24 juillet 2011 à 15:38 -0700, Dima Pasechnik a écrit :
> On Sunday, 24 July 2011 22:37:05 UTC+1, Rafael T wrote:
>
> The gap-system already has the ability to work with Coxeter
> groups:
> http://www.gap-system.org/Gap3/Manual3/C075S005.htm Maybe I
> could use
> some of their code?
> GAP 3 (not the current GAP 4) has it, as an interface to a package
> called Chevie (written mostly in Maple, if I recall right), but it's
> rather old unmaintained stuff.
I can't manage to use it now... So, it is perhaps broken these days (the
sage-combinat queue of patches is relatively experimental...).
To get the implementation of Coxeter groups in Sage, there is a lot of
things to do yourself.
****************************
See :
print gap3._install_hints()
Your attempt to start GAP3 failed, either because you do not have
have GAP3 installed, or because it is not configured correctly.
- If you do not have GAP3 installed, then you must download and
install it yourself because it is not distrubuted with Sage.
Here are some ways to obtain GAP3:
- There is an optional Sage package providing GAP3 pre-packaged
with several GAP3 packages:
http://trac.sagemath.org/sage_trac/ticket/8906
- Frank Luebeck maintains a GAP3 Linux executable, optimized
for i686 and statically linked for jobs of 2 GByte or more:
http://www.math.rwth-aachen.de/~Frank.Luebeck/gap/GAP3
- Jean Michel maintains a version of GAP3 pre-packaged with
CHEVIE and VKCURVE. It can be obtained here:
http://people.math.jussieu.fr/~jmichel/chevie/chevie.html
- Finally, you can download GAP3 from the GAP website below.
Since
GAP3 is no longer an officially supported distribution of GAP,
it
may not be easy to install this version.
http://www.gap-system.org/Gap3/Download3/download.html
- If you have GAP3 installed, then perhaps it is not configured
correctly. Sage assumes that you can start GAP3 with the command
/opt/gap3r4p4/bin/gap.sh. Alternatively, you can use the following
command
to point Sage to the correct command for your system.
gap3 = Gap3(command='/usr/local/bin/gap3')
********************************
Once you will have gap3 on your computer, it is not still ended. You
will have to make Sage know there Gap3 and chevie available.
On my computer, gap3 is at /opt/gap3r4p4/ . I tell it to sage like :
gap3 = Gap3(command='/opt/gap3r4p4/bin/gap.sh')
after that, i can do :
sage: gap3.console()
######## Lehrstuhl D fuer
Mathematik
### #### RWTH
Aachen
##
##
## # #######
#########
## # ## ## #
##
## # # ## #
##
#### ## ## # #
##
##### ### ## ## ##
##
######### # #########
#######
#
#
## Version 3
#
### Release 4.4
#
## # 18 Apr 97
#
##
#
## # Alice Niemeyer, Werner Nickel, Martin
Schoenert
## # Johannes Meier, Alex Wegner, Thomas
Bischops
## # Frank Celler, Juergen Mnich, Udo
Polis
### ## Thomas Breuer, Goetz Pfeiffer, Hans U.
Besche
###### Volkmar Felsch, Heiko Theissen, Alexander
Hulpke
Ansgar Kaup, Akos Seress, Erzsebet
Horvath
Bettina
Eick
For help
enter: ?<return>
gap> RequirePackage("chevie");
Welcome to the CHEVIE package, Version 4.devel (Feb 2010)
http://www.math.rwth-aachen.de/~CHEVIE for the stable version 3.1
http://www.math.jussieu.fr/~jmichel/chevie for this version
Meinolf Geck, Frank Luebeck, Gerhard Hiss,
Gunter Malle, Jean Michel, Goetz Pfeiffer
Lehrstuhl D fuer Mathematik, RWTH Aachen
Universit'e Paris VII
AG Computational Mathematics Universit"at Kassel
Galway University
This replaces the former weyl package. For first help type
?CHEVIE Version 4 -- a short introduction
gap> quit;;
sage:
*****************************
This is a good prerequisite before getting that you want. Even you got
that, I think you will still have to wait because something doesn't work
in loading chevie via the Gap3 interface. On my computer, the error is
there :
sage: W = CoxeterGroup(["A",2])
---------------------------------------------------------------------------
AssertionError Traceback (most recent call
last)
/opt/sage/devel/sage-combinat/<ipython console> in <module>()
/opt/sage/local/lib/python2.6/site-packages/sage/combinat/root_system/coxeter_group.pyc
in CoxeterGroup(*args, **kwds)
252 return
sage.libs.coxeter.coxeter_group.CoxeterGroup(cartan_type)
253
--> 254 assert is_chevie_available()
255 gap3.load_package("chevie")
256
AssertionError:
sage:
sage: gap3.load_package("chevie")
---------------------------------------------------------------------------
UnboundLocalError Traceback (most recent call
last)
/opt/sage/devel/sage-combinat/<ipython console> in <module>()
...
UnboundLocalError: local variable 'f' referenced before assignment
sage:
sage: from sage.combinat.root_system.complex_reflection_group import
is_chevie_available
sage: is_chevie_available()
False
***************************
A lot of people from combinat worked on that. To give somes manes, I
think about Saliola, Hivert, Thiery, ... But a lot of them are probably
not available these days.
Also, you will meet faster an expert by posting on sage-combinat-devel.
I thus send it to this groups.
Cheers,
Nicolas B.
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