setmod_ff

setmod_ff([prime|poly])

:: Sets/Gets the current base fields.

return

number or polynomial

prime

prime

poly

univariate polynomial irreducible over GF(2)

• If the argument is a non-negative integer prime, GF(prime) is set as the current base field.
• If the argument is a polynomial poly, GF(2^deg(poly mod 2)) = GF(2)[t]/(poly(t) mod2) is set as the current base field.
• If no argument is specified, the modulus indicating the current base field is returned. If the current base field is GF(prime), prime is returned. If it is GF(2^n), the defining polynomial is returned.
• Any irreducible univariate polynomial over GF(2) is available to set GF(2^n). However the use of defpoly_mod2() is recommended for efficiency.

[174] defpoly_mod2(100);
x^100+x^15+1
[175] setmod_ff(@@);
x^100+x^15+1
[176] setmod_ff();
x^100+x^15+1

References

section defpoly_mod2

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