public Rational GetNarrowParent(Rational r)
{
int lastLevel = r.GetHighPrimeIndex();
if (lastLevel >= _involvedPrimeCount)
{
return(default(Rational));
}
if (lastLevel <= _basePrimeIndex)
{
return(default(Rational)); // We don't draw lines between base intervals (e.g. 1/2 - 1 - 2 - 4).
}
//
Rational step = _narrows[lastLevel]; // last level step
if (step.IsDefault())
{
return(default(Rational)); //!!! exception ?
}
int lastPower = r.GetPrimePower(lastLevel); // last level coordinate
if (lastPower > 0)
{
return(r / step);
}
else
{
return(r * step);
}
}
public static Pow[] GetNarrowPowers(this Rational r, Rational[] narrows = null)
{
if (narrows == null)
{
narrows = NarrowUtils.GetDefault(r.GetInvolvedPowerCount());
}
int len = r.GetInvolvedPowerCount();
if (len > narrows.Length)
{
return(null);
}
Pow[] res = new Pow[len];
r = r.Clone();
for (int i = len - 1; i >= 0; --i)
{
Pow e = r.GetPrimePower(i);
res[i] = e;
if (e != 0)
{
r /= narrows[i].Power(e);
}
}
return(res);
}
public static Rational ValidateNarrow(Rational n)
{
if (n.IsDefault())
{
return(n); // invalid
}
int h = n.GetHighPrimeIndex();
if (h == -1)
{
return(default(Rational)); // "1" can't be a narrow
}
if (n.GetPrimePower(h) < 0) // max prime should be in nominator
{
n = Rational.One / n;
}
return(n);
}