Paul,
p is a polynomial over the base field. eval expects to return a
polynomial of the same type.
Perhaps this is what you intended?
(6) -> eval(p::POLY gf16, x,a)::gf16
2
(6) %A + 1
Type: FiniteFieldExtensionByPolynomial(PrimeField(2),?^4+?+1)
Regards,
Bill Page.
On Wed, Aug 10, 2011 at 5:13 PM, Paul Onions <[email protected]> wrote:
> I have the following problem when I try to evaluate a polynomial in a
> finite-field extension:
>
> -- START OF TRANSCRIPT --
> gf2 := PrimeField 2 -- the base field
>
> (1) PrimeField(2)
>
> Type: Type
> gf16 := FiniteFieldExtensionByPolynomial(gf2, x**4 + x + 1) -- the
> extension field
>
> (2) FiniteFieldExtensionByPolynomial(PrimeField(2),?^4+?+1)
>
> Type: Type
> a := index(2)$gf16 -- a primitive element of the extension field
>
> (3) %A
> Type: FiniteFieldExtensionByPolynomial(PrimeField(2),?
> ^4+?+1)
> order a -- check primitiveness
>
> (4) 15
> Type:
> PositiveInteger
> p := x**2 + 1 :: POLY gf2 -- a polynomial over the base field
>
> 2
> (5) x + 1
> Type:
> Polynomial(PrimeField(2))
> eval(p, x=a)
>
> There are 3 exposed and 0 unexposed library operations named
> equation having 2 argument(s) but none was determined to be
> applicable. Use HyperDoc Browse, or issue
> )display op equation
> to learn more about the available operations. Perhaps
> package-calling the operation or using coercions on the
> arguments
> will allow you to apply the operation.
>
> Cannot find a definition or applicable library operation named
> equation with argument type(s)
> Variable(x)
> FiniteFieldExtensionByPolynomial(PrimeField(2),?^4+?+1)
>
> Perhaps you should use "@" to indicate the required return
> type,
> or "$" to specify which version of the function you need.
> -- END OF TRANSCRIPT --
>
> where I expect
> eval(p,x=a)
> to give the same result as
> a**2 + 1
> which does indeed work, as follows:
>
> -- START OF TRANSCRIPT --
> (6) -> a**2 + 1
>
> 2
> (6) %A + 1
> Type: FiniteFieldExtensionByPolynomial(PrimeField(2),?
> ^4+?+1)
> -- END OF TRANSCRIPT --
>
> Any idea what I'm doing wrong?
>
> Thanks,
> Paul
>
> --
> You received this message because you are subscribed to the Google Groups
> "FriCAS - computer algebra system" group.
> To post to this group, send email to [email protected].
> To unsubscribe from this group, send email to
> [email protected].
> For more options, visit this group at
> http://groups.google.com/group/fricas-devel?hl=en.
>
>
--
You received this message because you are subscribed to the Google Groups
"FriCAS - computer algebra system" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/fricas-devel?hl=en.
