public void TestOrderFinder(IOrderFinder orderFinder)
{
for (long n = 2; n < 500; n++)
{
for (long a = 1; a < n; a++)
{
if (MathUtils.GCD(a, n) != 1)
{
continue;
}
long res = orderFinder.Find(a, n);
if (MathUtils.FastPowMod(a, res, n) != 1)
{
Assert.Fail("a^r is not congruent to one.", a, n, res, MathUtils.FastPowMod(a, res, n));
}
for (int rp = 1; rp < res; rp++)
{
if (MathUtils.FastPowMod(a, rp, n) == 1)
{
Assert.Fail("There is a smaller value r\' than r with a^r\' is congruent to one", a, n, res, rp);
}
}
}
}
}
long FindDivisor(long n)
{
if (PrimeChecker.Prime(n))
{
throw new Exception("Number is already prime, can't find any nontrivial divisor.");
}
if ((n & 1) == 0)
{
return(2);
}
var rt = FindRoot(n);
if (rt != -1)
{
return(rt);
}
while (true)
{
long a = (MathUtils.Random() % (n - 1)) + 1;
long g = MathUtils.GCD(n, a);
if (g != 1)
{
return(g);
}
long r = OrderFinder.Find(a, n);
if ((r & 1) != 0)
{
continue;
}
if (MathUtils.FastPowMod(a, r / 2, n) == n - 1)
{
continue;
}
long DivShare = MathUtils.FastPowMod(a, r / 2, n) - 1;
return(MathUtils.GCD(n, DivShare));
}
}