public static IPolynomial Pow(IPolynomial poly, int exponent)
{
if (exponent < 0)
{
throw new NotImplementedException("Raising a polynomial to a negative exponent not supported. Build this functionality if it is needed.");
}
else if (exponent == 0)
{
return(new Polynomial(new Term[] { new Term(1, 0) }));
}
else if (exponent == 1)
{
return(poly.Clone());
}
else if (exponent == 2)
{
return(Square(poly));
}
IPolynomial total = Polynomial.Square(poly);
int counter = exponent - 2;
while (counter != 0)
{
total = Polynomial.Multiply(total, poly);
counter -= 1;
}
return(total);
}
public static IPolynomial ExponentiateMod(IPolynomial startPoly, BigInteger s2, IPolynomial f, BigInteger p)
{
IPolynomial result = Polynomial.One;
if (s2 == 0)
{
return(result);
}
IPolynomial A = startPoly.Clone();
byte[] byteArray = s2.ToByteArray();
bool[] bitArray = new BitArray(byteArray).Cast <bool>().ToArray();
// Remove trailing zeros ?
if (bitArray[0] == true)
{
result = startPoly;
}
int i = 1;
int t = bitArray.Length;
while (i < t)
{
A = Field.ModMod(Polynomial.Square(A), f, p);
if (bitArray[i] == true)
{
result = Field.ModMod(Polynomial.Multiply(A, result), f, p);
}
i++;
}
return(result);
}
public static IPolynomial Product(IEnumerable <IPolynomial> polys)
{
IPolynomial result = null;
foreach (IPolynomial p in polys)
{
if (result == null)
{
result = p;
}
else
{
result = Polynomial.Multiply(result, p);
}
}
return(result);
}
public static IPolynomial ModPow(IPolynomial poly, BigInteger exponent, IPolynomial mod)
{
if (exponent < 0)
{
throw new NotImplementedException("Raising a polynomial to a negative exponent not supported. Build this functionality if it is needed.");
}
else if (exponent == 0)
{
return(Polynomial.One);
}
else if (exponent == 1)
{
return(poly.Clone());
}
else if (exponent == 2)
{
return(Polynomial.Square(poly));
}
IPolynomial total = Polynomial.Square(poly);
BigInteger counter = exponent - 2;
while (counter != 0)
{
total = Polynomial.Multiply(poly, total);
if (total.CompareTo(mod) < 0)
{
total = Field.Modulus(total, mod);
}
counter -= 1;
}
return(total);
}
public static IPolynomial Square(IPolynomial poly)
{
return(Polynomial.Multiply(poly, poly));
}