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);
}
}
private void UpdateRange()
{
_baseItem = default(Rational);
_basePrimeIndex = 0;
_involvedPrimeCount = 0;
//
int maxIndex = 0;
int minIndex = int.MaxValue;
//
foreach (Rational r in _items)
{
int i = r.GetHighPrimeIndex();
if (maxIndex < i)
{
maxIndex = i;
}
if (minIndex > i)
{
minIndex = i;
_baseItem = r;
}
}
//
_involvedPrimeCount = maxIndex + 1;
_basePrimeIndex = _baseItem.GetHighPrimeIndex();
}
public static Rational MakeNarrow(Rational r, Rational b)
{
if (r.GetHighPrimeIndex() == b.GetHighPrimeIndex())
{
return(r); // can't narrow on same prime level
}
double r_ = r.ToDouble();
double b_ = b.ToDouble();
double l = Math.Log(r_, b_); // e.g. 1.58 for {3, 2}
Pow e = (Pow)(l + 0.25); // something between Floor and Round
r /= b.Power(e);
return(r);
}
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);
}
private bool SetNarrow(Rational n)
{
// make high prime positive
n = NarrowUtils.ValidateNarrow(n);
if (n.IsDefault())
{
return(false);
}
// set narrow to the array - by high prime index
int h = n.GetHighPrimeIndex();
if (0 <= h && h < _narrows.Length)
{
_narrows[h] = n;
return(true);
}
return(false);
}
public static Rational MakeNarrow(Rational r, int basePrimeIndex)
{
if (r.GetHighPrimeIndex() <= basePrimeIndex)
{
return(r); // can't narrow
}
r = ValidateNarrow(r);
//
double rr = r.ToDouble();
if (rr < 1.0)
{
return(r); // e.g. for 5/6 - doubtful !!!
}
int b = Utils.GetPrime(basePrimeIndex); // base prime: 2, 3,..
double l = Math.Log(rr - 1.0, b);
Pow e = (Pow)Math.Round(l);
Long d = Utils.Pow(b, e);
r /= d;
return(r);
}