public static bool IsPrime(int n, int error)
{
int a;
var random = new Random();
for (int i = 0; i < error; i++)
{
a = random.Next(2, n);
if (NumbersOperations.NSD(a, n) > 1)
{
return(false);
}
if (NumbersOperations.ModPow(a, (n - 1) / 2, n) != (n + Jacobi(a, n)) % n)
{
return(false);
}
}
return(true);
}
private static int Jacobi(int x, int n)
{
if (NumbersOperations.NSD(x, n) != 1)
{
return(0);
}
int result = 1;
do
{
int y = 0;
while (x % 2 == 0)
{
y += 1;
x /= 2;
}
if ((y % 2 == 1 && (n % 8 == 3 || n % 8 == 5)) ||
(x % 4 == 3 && n % 4 == 3))
{
result = -result;
}
//if (x % 4 == 3 && n % 4 == 3)
//{
// result = -result;
//}
int temp = x;
x = n % temp;
n = temp;
} while (x != 0);
return(result);
}