private static XInt Swing3(PrimeSieve sieve, int n)
{
var primorial = Task.Factory.StartNew <XInt>(() =>
{
var start = sieve.NextPrime(n / 2);
start = sieve.NextPrime(start);
return(sieve.GetPrimorial(start, n, 2));
});
var count = 0;
var rootN = XMath.FloorSqrt(n);
var startPrime = sieve.NextPrime(rootN);
startPrime = sieve.NextPrime(startPrime);
var aPrimes = sieve.GetPrimeCollectionEveryOther(5, rootN);
var bPrimes = sieve.GetPrimeCollectionEveryOther(startPrime, n / 3);
var primeList = new int[aPrimes.NumberOfPrimes + bPrimes.NumberOfPrimes];
foreach (var prime in aPrimes)
{
int q = n, p = 1;
while ((q /= prime) > 0)
{
if ((q & 1) == 1)
{
p *= prime;
}
}
if (p > 1)
{
primeList[count++] = p;
}
}
foreach (var prime in bPrimes.Where(prime => ((n / prime) & 1) == 1))
{
primeList[count++] = prime;
}
var primeProduct = XMath.Product(primeList, 0, count);
return(primeProduct * primorial.Result);
}
XInt Swing(int n)
{
if (n < 33)
{
return(SmallOddSwing[n]);
}
var primorial = Task.Factory.StartNew <XInt>(() =>
this.sieve.GetPrimorial(n / 2 + 1, n));
var count = 0;
var rootN = XMath.FloorSqrt(n);
var aPrimes = this.sieve.GetPrimeCollection(3, rootN);
var bPrimes = this.sieve.GetPrimeCollection(rootN + 1, n / 3);
var piN = aPrimes.NumberOfPrimes + bPrimes.NumberOfPrimes;
var primeList = new int[piN];
foreach (var prime in aPrimes)
{
int q = n, p = 1;
while ((q /= prime) > 0)
{
if ((q & 1) == 1)
{
p *= prime;
}
}
if (p > 1)
{
primeList[count++] = p;
}
}
foreach (var prime in bPrimes.Where(prime => ((n / prime) & 1) == 1))
{
primeList[count++] = prime;
}
var primeProduct = XMath.Product(primeList, 0, count);
return(primeProduct * primorial.Result);
}
private XInt Swing(int n)
{
if (n < 33)
{
return(SmallOddSwing[n]);
}
int count = 0, rootN = XMath.FloorSqrt(n);
var aPrimes = this.sieve.GetPrimeCollection(3, rootN);
var bPrimes = this.sieve.GetPrimeCollection(rootN + 1, n / 3);
foreach (var prime in aPrimes)
{
int q = n, p = 1;
while ((q /= prime) > 0)
{
if ((q & 1) == 1)
{
p *= prime;
}
}
if (p > 1)
{
this.primeList[count++] = p;
}
}
foreach (var prime in bPrimes.Where(prime => ((n / prime) & 1) == 1))
{
this.primeList[count++] = prime;
}
var primorial = this.sieve.GetPrimorial(n / 2 + 1, n);
return(primorial * XMath.Product(this.primeList, 0, count));
}
private XInt NestedSquare(int len)
{
if (len == 0)
{
return(XInt.One);
}
var i = 0;
var mult = this.multiList[0];
while (mult > 1)
{
if ((mult & 1) == 1) // is mult odd ?
{
this.primeList[len++] = this.primeList[i];
}
this.multiList[i++] = mult >> 1;
mult = this.multiList[i];
}
return(XMath.Product(this.primeList, i, len - i)
* XInt.Pow(this.NestedSquare(i), 2));
}