r= x^12 - x^10 + x^8 - x^6 + x^4 - x^2 + 1 q= (x^18 - 2*x^16 + x^14 + x^4 + 2*x^2 + 1 ) / 4 P= x^9-2*x^8+x^7+x^2+2*x+1 v= x^2