/// <summary>
/// Cox-de Boor recursion formula implementation.
/// </summary>
protected Func <double, double> GetBasis(int i, int j, KnotSet knots)
{
Func <double, double> func = (t) =>
{
double t_i = knots.GetIndexOf(i);
double t_iplus1 = knots.GetIndexOf(i + 1);
if (j == 0)
{
if (t_i <= t && t < t_iplus1)
{
return(1);
}
else
{
return(0);
}
}
double coef1 = GetCoef(i, j, t, knots);
double coef2 = 1 - GetCoef(i + 1, j, t, knots);
Func <double, double> firstTerm = GetBasis(i, j - 1, knots);
Func <double, double> secondTerm = GetBasis(i + 1, j - 1, knots);
double first = firstTerm(t);
double second = secondTerm(t);
return(coef1 * first + coef2 * second);
};
return(func);
}
/// <summary>
/// Cox-de Boor recursion formula implementation.
/// </summary>
protected double GetCoef(int i, int j, double t, KnotSet knots)
{
if (knots.GetIndexOf(i + j) == knots.GetIndexOf(i))
{
return(0);
}
return((double)(t - knots.GetIndexOf(i)) / (double)(knots.GetIndexOf(i + j) - knots.GetIndexOf(i)));
}
public void GetIndexOf()
{
double[] knots = null;
KnotSet knotSet = null;
double r;
double a;
knots = new double[] { 1, 2, 3, 4 };
knotSet = new KnotSet(knots);
r = knotSet.GetIndexOf(1);
a = 2;
Assert.IsTrue(r == a);
knots = new double[] { 1, 2, 3, 4 };
knotSet = new KnotSet(knots);
Assert.ThrowsException <ArgumentOutOfRangeException>(() => knotSet.GetIndexOf(-1));
knots = new double[] { 1, 2, 3, 4 };
knotSet = new KnotSet(knots);
Assert.ThrowsException <ArgumentOutOfRangeException>(() => knotSet.GetIndexOf(5));
knots = new double[] { 1, 2, 3, 4 };
knotSet = new KnotSet(knots, false);
r = knotSet.GetIndexOf(-1);
a = 1;
Assert.IsTrue(r == a);
knots = new double[] { 1, 2, 3, 4 };
knotSet = new KnotSet(knots, false);
r = knotSet.GetIndexOf(7);
a = 4;
Assert.IsTrue(r == a);
}