polynomial calculations over Z/Zp (for prime p)?

[Jeff Nye]

(12-24-2013 04:09 AM)Han Wrote:  

Code:


p:=3;
p1:=[ 12 13 -20 5 ] % p;
p2:=(12x^3 + 13x^2 - 20x + 5) % p;
p3:=poly[ 12 13 -20 5 ] % p;

These didn't work for me (using the latest firmware).

However, last night I stumbled upon the CAS %%(n,p) operator, which seems to be the % operator in xcas. With %% instead of %, example p1 worked fine. Example p2 produces a polynomial with non-modular coefficients. For example p3, I needed to say poly([ 12 13 -20 5 ] %% p).

Linear algebra seems to work with integers mod p. The expression [[4,3],[5,1]]%%3 defines a matrix of integers mod 3.