addOrSubstract method

GFPoly addOrSubstract(
  1. GFPoly other
)

Implementation

GFPoly addOrSubstract(GFPoly other) {
  if (zero()) {
    return other;
  } else if (other.zero()) {
    return this;
  }
  List<int> smallCoeff = coefficients;
  List<int> largeCoeff = other.coefficients;
  if (smallCoeff.length > largeCoeff.length) {
    final List<int> swap = largeCoeff;
    largeCoeff = smallCoeff;
    smallCoeff = swap;
  }
  final List<int> sumDiff = List<int>.filled(largeCoeff.length, 0);
  final int lenDiff = largeCoeff.length - smallCoeff.length;
  sumDiff.setAll(0, largeCoeff.sublist(0, lenDiff));
  for (int i = lenDiff; i < largeCoeff.length; i++) {
    sumDiff[i] = gf.addOrSub(smallCoeff[i - lenDiff], largeCoeff[i]);
  }
  return GFPoly(gf, sumDiff);
}