public static PrimeNumberState IsPrime(BigInteger number)
{
if (number <= 3)
{
return(PrimeNumberState.Prime);
}
if (number.IsEven)
{
return(PrimeNumberState.Composite);
}
if (!NumbersAnalys.IsFermatNumber(number))
{
throw new Exception("It is not a fermat number!");
}
if (!int.TryParse(BigInteger.Divide(BigInteger.Subtract(number, 1), 2).ToString(), out var exp))
{
throw new Exception("Can't parse to int");
}
var sub = BigInteger.Subtract(BigInteger.Pow(number, exp), -1);
var remainder = BigInteger.Remainder(sub, number);
return(remainder == 0 ? PrimeNumberState.Prime : PrimeNumberState.Composite);
}
private void AnalysButton_Click(object sender, RoutedEventArgs e)
{
if (!BigInteger.TryParse(NumberInput.Text, out var number))
{
var result = MessageBox.Show("Incorrect input!", "Error", MessageBoxButton.OK);
if (result == MessageBoxResult.OK)
{
NumberInput.Clear();
}
return;
}
Busy.Visibility = Visibility.Visible;
var primeResult = NumbersAnalys.AnalysNumber(number);
var window = new PrimalityTestChoose(primeResult, number);
Busy.Visibility = Visibility.Hidden;
window.ShowDialog();
}
private static PrimeNumberState PrimeTest(BigInteger number, CancellationToken token)
{
if (number.IsEven)
{
return(number == 2 ? PrimeNumberState.Prime : PrimeNumberState.Composite);
}
if (!NumbersAnalys.IsMersenneNumber(number))
{
throw new Exception("Not a Mersenne number");
}
var num = BigInteger.Log(number + 1, 2);
var s = new BigInteger(4);
for (var i = 3; i <= num; i++)
{
token.ThrowIfCancellationRequested();
s = (BigInteger.ModPow(s, 2, number) - 2) % number;
}
return(s == BigInteger.Zero ? PrimeNumberState.Prime : PrimeNumberState.Composite);
}
