public void TestPrimeChecker(IPrimeChecker primeChecker)
{
if (primeChecker.Prime(1))
{
Assert.Fail("PrimeChecker claims 1 is a prime");
}
for (int p = 2; p < 10000; p++)
{
bool isPrime = primeChecker.Prime(p);
int c = -1;
for (int i = 2; i < p; i++)
{
if (p % i == 0)
{
c = i;
}
}
if (isPrime && c != -1)
{
Assert.Fail("PrimeChecker claimed it's prime, but " + c.ToString() + " divides " + p.ToString(), p, c);
}
else if (c == -1 && !isPrime)
{
Assert.Fail("PrimeChecker claimed it's composite, but we didn't find any divisor", p);
}
}
}
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));
}
}