private ulong Rho(ulong n, ulong xInit, ulong c, IReducer <ulong> reducer)
{
if ((n & 1) == 0)
{
return(2);
}
var x = reducer.ToResidue(xInit);
var y = x.Copy();
var ys = x.Copy();
var r = 1;
var m = batchSize;
var cPrime = reducer.ToResidue(c);
var one = reducer.ToResidue(1);
var diff = one.Copy();
var q = one.Copy();
var g = (ulong)1;
do
{
x.Set(y);
for (int i = 0; i < r; i++)
{
AdvanceF(y, cPrime);
}
var k = 0;
while (k < r && g == 1)
{
ys.Set(y);
var limit = Math.Min(m, r - k);
q.Set(one);
for (int i = 0; i < limit; i++)
{
AdvanceF(y, cPrime);
q.Multiply(diff.Set(x).Subtract(y));
}
g = IntegerMath.GreatestCommonDivisor(q.Value, n);
k += limit;
}
r <<= 1;
}while (g == 1);
if (g.CompareTo(n) == 0)
{
// Backtrack.
do
{
AdvanceF(ys, cPrime);
g = IntegerMath.GreatestCommonDivisor(diff.Set(x).Subtract(ys).Value, n);
}while (g == 1);
}
if (g.CompareTo(n) == 0)
{
return(0);
}
return(g);
}
private Number <T> Rho(Number <T> n, Number <T> xInit, Number <T> c, IReducer <T> reducer)
{
#if DIAG
Console.WriteLine("xInit = {0}, c = {1}", xInit, c);
#endif
if (n.IsEven)
{
return(2);
}
var x = reducer.ToResidue(xInit);
var y = x.Copy();
var ys = x.Copy();
var r = (long)1;
var m = batchSize;
var cPrime = reducer.ToResidue(c);
var one = reducer.ToResidue(1);
var diff = one.Copy();
var q = one.Copy();
var g = (Number <T>) 1;
var count = (long)0;
do
{
x.Set(y);
for (int i = 0; i < r; i++)
{
AdvanceF(y, cPrime);
++count;
}
var k = (long)0;
while (k < r && g == 1)
{
ys.Set(y);
var limit = Math.Min(m, r - k);
q.Set(one);
for (int i = 0; i < limit; i++)
{
AdvanceF(y, cPrime);
q.Multiply(diff.Set(x).Subtract(y));
}
g = Number <T> .GreatestCommonDivisor(q.Value, n);
k += limit;
count += limit << 1;
}
r <<= 1;
}while (g == 1);
#if DIAG
Console.WriteLine("count = {0}", count);
#endif
if (g.CompareTo(n) == 0)
{
// Backtrack.
do
{
AdvanceF(ys, cPrime);
g = Number <T> .GreatestCommonDivisor(diff.Set(x).Subtract(ys).Value, n);
}while (g == 1);
}
if (g.CompareTo(n) == 0)
{
return(0);
}
return(g);
}