On Dec 12, 12:47 am, achrzesz <achrz...@wp.pl> wrote: > On Dec 12, 12:41 am, Juan Grados <juan...@gmail.com> wrote: > > > > > but when I put this polynomial x^8+x^7+x^4+x^3+x+1 I get ValueError: > > finite field modulus must be irreducible but it is not > > > 2011/12/11 achrzesz <achrz...@wp.pl> > > > > On Dec 12, 12:10 am, juaninf <juan...@gmail.com> wrote: > > > > Hi everybody > > > > > I want choose different minimal polynomial to build a Galois Field > > > > 2^m, how? > > > > > For example: m = 8 > > > > > sageF.<a>=GF(2^8) > > > > sage:print a.minpoly() > > > > I get ... > > > > x^8 + x^4 + x^3 + x^2 + 1 > > > > but I want now other polynomial for example > > > > x^8+x^7+x^4+x^3+x+1 > > > > How? > > > > > thanks > > > > sage: K.<z>=GF(2)[] > > > sage: F.<x>=GF(2^8,name='x',modulus=z^8+z^4+z^3+z+1) > > > sage: F > > > Finite Field in x of size 2^8 > > > sage: F.polynomial() > > > x^8 + x^4 + x^3 + x + 1 > > > > Andrzej Chrzeszczyk > > > > -- > > > To post to this group, send email to sage-support@googlegroups.com > > > To unsubscribe from this group, send email to > > > sage-support+unsubscr...@googlegroups.com > > > For more options, visit this group at > > >http://groups.google.com/group/sage-support > > > URL:http://www.sagemath.org > > > -- > > --------------------------------------------------------------------- > > Juan del Carmen Grados Vásquez > > Laboratório Nacional de Computação Científica > > Tel: +55 24 2233-6260 > > (http://www.lncc.br/)http://juaninf.blogspot.com > > --------------------------------------------------------------------- > > Your poly is not irreducible > sage: f.factor() > (z + 1) * (z^7 + z^3 + 1) > > Andrzej Chrzeszczyk
If you really need a reducible poly then sage: F.<x>=GF(2^8,name='x',modulus=z^8+z^4+z^3+z^2+1,proof=False) Andrzej Chrzeszczyk -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
