evaluate function
Implementation
int evaluate(Uint8List coef, int x) {
if (coef.isEmpty) return 0;
int result = coef[coef.length - 1];
for (int i = coef.length - 2; i >= 0; i--) {
result = _gfMult(result, x);
result = _gfAdd(result, coef[i]);
}
return result;
}