public OmgNum FindFactor(OmgNum n, int maxIterations = -1)
{
m_iterations = 0;
m_current = n;
OmgNum x = OmgOp.Random(1.ToOmgNum(), OmgOp.Subtract(n, 2.ToOmgNum()));
OmgNum y = 1.ToOmgNum();
OmgNum i = 0.ToOmgNum();
OmgNum stage = 2.ToOmgNum();
OmgNum sub = OmgOp.Subtract(x, y).MakeAbs();
OmgNum gcd = OmgOp.Gcd(n, sub);
sub.Release();
while (gcd.IsOne())
{
if (maxIterations >= 0 && m_iterations++ > maxIterations)
{
return(null);
}
if (OmgOp.Equal(i, stage))
{
y.Release();
y = new OmgNum(x);
stage.MultByTwo();
}
OmgNum xSquare = OmgOp.Multiply(x, x).Inc();
x.Release();
x = OmgOp.Mod(xSquare, n);
xSquare.Release();
i.Inc();
sub = OmgOp.Subtract(x, y).MakeAbs();
gcd.Release();
gcd = OmgOp.Gcd(n, sub);
sub.Release();
}
return(gcd);
}
private OmgNum _MakeFastPow(OmgNum left, RawNum right, OmgNum mod)
{
if (right.IsZero())
{
var res = OmgPool.GetRawZero();
res.Digits.Add(1);
return(new OmgNum(res));
}
var rightCopy = OmgPool.GetRawZero();
rightCopy.CopyFrom(right);
bool even = (rightCopy.Digits[0] & 1) == 0;
if (even)
{
rightCopy.DivByTwo();
var p = _MakeFastPow(left, rightCopy, mod);
OmgNum powSquare = OmgOp.Multiply(p, p);
OmgNum powSquareModded = OmgOp.Mod(powSquare, mod);
powSquare.Release();
p.Release();
OmgPool.ReleaseNumber(rightCopy);
return(powSquareModded);
}
else
{
_SubOne(rightCopy);
var p = _MakeFastPow(left, rightCopy, mod);
OmgNum powPlusOne = OmgOp.Multiply(p, left);
OmgNum powPlusOneModded = OmgOp.Mod(powPlusOne, mod);
powPlusOne.Release();
p.Release();
OmgPool.ReleaseNumber(rightCopy);
return(powPlusOneModded);
}
}
public bool IsPrime(OmgNum tested)
{
foreach (var prime in s_smallPrimes)
{
if (OmgOp.Less(tested, prime) || OmgOp.Equal(tested, prime))
{
return(true);
}
var mod = OmgOp.Mod(tested, prime);
bool isComposite = mod.IsZero();
mod.Release();
if (isComposite)
{
return(false);
}
}
return(true);
}
