/// <summary>
/// Calcula o resto da divisão entre dois polinómios.
/// </summary>
/// <param name="dividend">O dividendo.</param>
/// <param name="divisor">O divisor.</param>
/// <returns>O resto.</returns>
/// <exception cref="ArgumentNullException">Caso algum dos argumentos seja nulo.</exception>
/// <exception cref="ArgumentException">Se os polinómios contiverem variáveis cujos nomes são diferentes.</exception>
/// <exception cref="DivideByZeroException">Se o divisor for uma unidade aditiva.</exception>
public GeneralDegUnivarPolynomNormalForm <CoeffType, DegreeType> Rem(
GeneralDegUnivarPolynomNormalForm <CoeffType, DegreeType> dividend,
GeneralDegUnivarPolynomNormalForm <CoeffType, DegreeType> divisor)
{
if (dividend == null)
{
throw new ArgumentNullException("dividend");
}
else if (divisor == null)
{
throw new ArgumentNullException("divisor");
}
else if (divisor.VariableName != divisor.VariableName)
{
throw new ArgumentException("Polynomials must share the same variable name in order to be operated.");
}
else
{
if (this.IsAdditiveUnity(divisor))
{
throw new DivideByZeroException("Can't divide by the null polynomial.");
}
else if (this.IsAdditiveUnity(dividend))
{
return(this.AdditiveUnity);
}
else if (this.integerNumber.Compare(divisor.Degree, dividend.Degree) > 0)
{
return(dividend.Clone());
}
else
{
var remainderSortedCoeffs = dividend.GetOrderedCoefficients(this.integerNumber);
var divisorSorteCoeffs = divisor.GetOrderedCoefficients(this.integerNumber);
var remainderLeadingDegree = remainderSortedCoeffs.Keys[remainderSortedCoeffs.Keys.Count - 1];
var divisorLeadingDegree = divisorSorteCoeffs.Keys[divisorSorteCoeffs.Keys.Count - 1];
var inverseDivisorLeadingCoeff = this.field.MultiplicativeInverse(divisorSorteCoeffs[divisorLeadingDegree]);
while (this.integerNumber.Compare(remainderLeadingDegree, divisorLeadingDegree) >= 0 &&
remainderSortedCoeffs.Count > 0)
{
var remainderLeadingCoeff = remainderSortedCoeffs[remainderLeadingDegree];
var differenceDegree = this.integerNumber.Add(
remainderLeadingDegree,
this.integerNumber.AdditiveInverse(divisorLeadingDegree));
var factor = this.field.Multiply(
remainderLeadingCoeff,
inverseDivisorLeadingCoeff);
remainderSortedCoeffs.Remove(remainderLeadingDegree);
for (int i = 0; i < divisorSorteCoeffs.Keys.Count - 1; ++i)
{
var currentDivisorDegree = divisorSorteCoeffs.Keys[i];
var currentCoeff = this.field.Multiply(
divisorSorteCoeffs[currentDivisorDegree],
factor);
currentDivisorDegree = this.integerNumber.Add(currentDivisorDegree, differenceDegree);
var addCoeff = default(CoeffType);
if (remainderSortedCoeffs.TryGetValue(currentDivisorDegree, out addCoeff))
{
addCoeff = this.field.Add(
addCoeff,
this.field.AdditiveInverse(currentCoeff));
if (this.field.IsAdditiveUnity(addCoeff))
{
remainderSortedCoeffs.Remove(currentDivisorDegree);
}
else
{
remainderSortedCoeffs[currentDivisorDegree] = addCoeff;
}
}
else
{
remainderSortedCoeffs.Add(
currentDivisorDegree,
this.field.AdditiveInverse(currentCoeff));
}
}
if (remainderSortedCoeffs.Count > 0)
{
remainderLeadingDegree = remainderSortedCoeffs.Keys[remainderSortedCoeffs.Keys.Count - 1];
}
else
{
remainderLeadingDegree = this.integerNumber.AdditiveUnity;
}
}
var remainder = new GeneralDegUnivarPolynomNormalForm <CoeffType, DegreeType>(
remainderSortedCoeffs,
this.variableName,
this.field,
this.integerNumber);
return(remainder);
}
}
}
