public int GetPeriodsOfSquareRoot(int N)
{
int a0 = GetClosestIntegertToSquare(N);
if (a0 * a0 == N)
{
return(0);
}
List <PeriodParameters> periodParameterList = new List <PeriodParameters>();
var periodParameters = new PeriodParameters {
an = a0, sub = -a0, f = 1.0
};
periodParameterList.Add(periodParameters);
while (periodParameterList.Count < 300)
{
periodParameters = CalcNextPeriodParameters(a0, N, periodParameters);
periodParameterList.Add(periodParameters);
var treff = periodParameterList.Where(r => r.an == periodParameters.an && r.sub == periodParameters.sub && Math.Abs(r.f - periodParameters.f) < 0.10).ToList();
if (treff.Count() == 2)
{
int index = periodParameterList.IndexOf(treff[0]);
int index2 = periodParameterList.Count() - 1;
return(index2 - index);
}
}
throw new Exception($"Periode ikke funnet for {N}");
}
public PeriodParameters CalcNextPeriodParameters(int a0, int N, PeriodParameters tt)
{
int f2 = N - tt.sub * tt.sub;
int an = 0;
while (-((an + 1) * f2 / tt.f) + (-1) * tt.sub >= -a0)
{
an++;
}
int sub = (int)-((an) * f2 / tt.f) + (-1) * tt.sub;
var nextPeriodParameters = new PeriodParameters {
an = an, sub = sub, f = (f2 / tt.f)
};
return(nextPeriodParameters);
}