public bool IsPrime(BigInteger number)
{
if (number < TWO)
{
return(false);
}
if (number == TWO)
{
return(true);
}
if (number == THREE)
{
return(true);
}
if (number % TWO == ZERO)
{
return(false);
}
if (BaseSequence == null)
{
BaseSequence = MillerRabinHelpers.RandomBases(10, number);
}
var minone = number - ONE; //should be even;
var d = minone;
BigInteger r = 0;
while (d % 2 == 0)
{
r++;
d >>= 1; //divide by 2
}
foreach (var a in BaseSequence)
{
var x = a * d % number;
if (x == ONE || x == minone)
{
continue;
}
for (BigInteger i = r - ONE; i > ZERO; i--)
{
x = BigInteger.ModPow(x, 2, number);
if (x == minone)
{
continue;
}
}
return(false);
}
return(true);
}
public bool IsPrime(BigInteger n)
{
if (BaseSequence == null)
{
BaseSequence = MillerRabinHelpers.JimSinclair2011();
}
//make sure n in odd and n > 3
if (n < TWO)
{
return(false);
}
if (n == TWO || n == THREE)
{
return(true);
}
if (n % TWO == ZERO)
{
return(false);
}
var m = n - ONE;
// u will be even, as n is required to be odd
var u = m >> 1;
long t = 1; //long should work for n up to 2^(2^63) ~ (2.7 pentillion digits)
//while even
while (u % TWO == ZERO)
{
t++;
u >>= 1;
}
foreach (var b in BaseSequence)
{
var a = b;
if (a >= n)
{
a %= n;
}
if (a == 0)
{
continue;
}
var x = BigInteger.ModPow(a, u, n);
if (x == ONE || x == m)
{
continue;
}
long i;
for (i = 1; i < t; i++)
{
x = x * x % n;
if (x == ONE)
{
return(false);
}
if (x == m)
{
break;
}
}
// if we didn't break, the number is composite
if (i == t)
{
return(false);
}
}
return(true);
}
