Power in $\mathbb {Z}$/p$\mathbb {Z}$ and in $\mathbb {Z}$/p$\mathbb {Z}$[x] : ^

To compute a to the power n in $\mathbb {Z}$/p$\mathbb {Z}$, we use the operator ^. Xcas implementation is the binary power algorithm.
Input :

(5%13)^2

Output :

-1%13

To compute A to the power n in $\mathbb {Z}$/p$\mathbb {Z}$[x], we use the operator ^ and the normal command .
Input :

normal(((2*x+1)%13)^5)

Output :

(6%13)*x^5+(2%13)*x^4+(2%13)*x^3+(1%13)*x^2+(-3%13)*x+1%13

because 10 = - 3 ( mod 13)  40 = 1 ( mod 13)  80 = 2 ( mod 13)  32 = 6 ( mod 13).