Hi Alexander,
How to edit the value of dictionary?How to append a function to a list which is
a value of dictionary?
Regards,
Martin
> Subject: Re: [GAP Forum] which function of dictionary can use polynomial or
> function as key
> From: hul...@math.colostate.edu
> Date: Wed, 24 Sep 2014 09:27:04 -0600
> CC: fo...@gap-system.org
> To: tesl...@hotmail.com
>
> Dear Forum,
>
> On Sep 24, 2014, at 9/24/14 3:21, Lee Martin CCNP <tesl...@hotmail.com> wrote:
>
> > would like to use rational function as key in dictionary like table
> > function in maple
> > which function is a dictionary can use function as key and value as list to
> > store ideals.
>
> Lookup dictionaries currently work with rational functions, e.g:
>
> gap> R:=PolynomialRing(Rationals,["x","y","z"]);AssignGeneratorVariables(R);
>
> Rationals[x,y,z]
> #I Assigned the global variables [ x, y, z ]
>
> gap> d:=NewDictionary(x,true);
> <object>
> gap> AddDictionary(d,x,1);
> gap> AddDictionary(d,y,2);
> gap> LookupDictionary(d,x);
> 1
> gap> LookupDictionary(d,z);
> fail
> gap> AddDictionary(d,x/y,2);
> gap> LookupDictionary(d,z);
> fail
> gap> LookupDictionary(d,x/y);
> 2
>
> Instead of numbers you should be able to store arbitrary associated
> information. However internally lists will be made immutable, so if your
> ideal list is expected to grow you would need to keep a separate (mutable)
> list of the ideal lists, storing only an index in the dictionary.
>
> I note that
>
> gap> RepresentationsOfObject(d);
> [ "IsComponentObjectRep", "IsDictionaryDefaultRep", "IsListDictionary",
> "IsListLookupDictionary", "IsSortDictionary", "IsSortLookupDictionary" ]
>
> this currently uses sorted lists internally and not yet hashing. To enable
> hashing, one would have to add a method for SparseHashKey for rational
> functions, which currently is not on the list of features.
>
> Best,
>
> Alexander Hulpke
>
>
> > Regards,
> > Martin
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>
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