On Jan 11, 12:07 am, javier <vengor...@gmail.com> wrote: > Patch submitted athttp://sagetrac.org/sage_trac/ticket/7890 > > the conversion of matrices only works when the conversion of the gap > ring works. In particular, it fails for cyclotomic fields, cyclotomic > rings, and finite fields of non-prime order. I have also modified the > _matrix_ method so that if no ring is given it tries to pick it up > from the first matrix entry. > > To make this patch *really* useful conversion for all the missing > kinds of rings and fields should be implemented. For GF(p^x) the only > thing that needs to be done is to expand the p^x part (gap actually > returns something like "GF(2^4)" rather than "GF(16)" into a number > and then call the sage conversion specifying a generator name. you can ask GAP to compute the size of the finite field: gap> Size(Field(Z(2^4))); 16 and use it to set up the Sage field.
> > For cyclotomic and other kinds of fields some more work is needed. > > Since GAP has two methods (Ring() and Field()) that are relevant here, > it would be great to have a way of deciding which one should be > called. > > Any further work along these lines will be most welcome! > > Cheers > J > > On Jan 10, 2:37 pm, Dima Pasechnik <dimp...@gmail.com> wrote: > > > > > Javier, > > > [...] > > > > So, it wasn't that hard (for matrices) after all. > > Good! > > > I don't know whether/ > > > how this can be applied to the E(9) thing unless there is an > > > IsSomething gap method that can be used for them. > > > Sure, there is > > IsCyclotomic > > and IsIntegralCyclotomic > > for cyclotomics, resp., cyclotomic integers: > > > gap> IsIntegralCyclotomic(E(9)); > > true > > gap> Field(E(9)); > > CF(9) > > > and > > > IsFFE for finite field elements: > > > gap> IsFFE(Z(5)); > > true > > gap> Field(Z(5)); > > GF(5) > > > for more general fields and for rings it's also doable... > > > Cheers, > > Dima > > > > I'll prepare some doctests and upload a first patch. > > > > Cheers > > > J
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