I meant: "The function assumes that f or g is not constant" instead of
"both primitive". As far as I understand, this is the only case where
something is broken, isn't it?

2015-01-27 17:20 UTC+01:00, Bill Hart <[email protected]>:
> I'm not sure what you mean. The flint documentation already disallows this
> case. It can only occur when there is nontrivial content. This is
> presumably why it is disallowed in flint's xgcd function.
>
> On Tuesday, 27 January 2015 17:11:35 UTC+1, vdelecroix wrote:
>>
>> Then it will be much simpler to adapt. Could you update the
>> specification of the function in the FLINT documentation then?
>>
>> Vincent
>>
>> 2015-01-27 16:51 UTC+01:00, Bill Hart <[email protected]
>> <javascript:>>:
>> > I remember the problem now.
>> >
>> > resultant(R(2), R(2)) = 1
>> >
>> > since it is an empty product.
>> >
>> > But there is no Z-linear combination of R(2) and R(2) which gives 1. So
>> >
>> the
>> >
>> > input has to be disallowed.
>> >
>> > It's only a problem for constant polynomial inputs that are not coprime
>> >
>> (as
>> >
>> > elements of Z) though. For higher degrees there are powers of the
>> contents
>> > that the polynomials can be multiplied by that will work.
>> >
>> > On Tuesday, 27 January 2015 16:28:46 UTC+1, Bill Hart wrote:
>> >>
>> >> For the time being I'm just going to modify Nemo. It would probably be
>> >>
>> >> inefficient to do anything else.
>> >>
>> >> On Tuesday, 27 January 2015 16:22:39 UTC+1, vdelecroix wrote:
>> >>>
>> >>> Hi Bill,
>> >>>
>> >>> 2015-01-27 16:16 UTC+01:00, Bill Hart <[email protected]>:
>> >>> > This turns out not to be a bug.
>> >>> >
>> >>> > The documentation requires that the inputs be primitive, which in
>> the
>> >>> > example given, they aren't. The function does work if passed the
>> >>> > polynomials R(1) and R(1).
>> >>>
>> >>> I see. Thanks I will update the trac ticket and the way we use the
>> >>> function.
>> >>>
>> >>> > However, this bug also exists in Nemo. So thanks for pointing it
>> out. I
>> >>> >
>> >>> can
>> >>> >
>> >>> > fix that, at least.
>> >>>
>> >>> Do you mean that you will change the specification of the FLINT
>> >>> function or that you will only modify Nemo ?
>> >>>
>> >>> Vincent
>> >>>
>> >>
>> >
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