public static double[] cubicSpline(double[] x, double[] y)
{
double[] curve = new double[(int)x[x.Length - 1]];
var spline = CubicSpline.InterpolateNaturalInplace(x, y);
for (int i = 0; i < curve.Length; i++)
{
curve[i] = spline.Interpolate(i);
}
return(curve);
}
/// <summary>
/// Interpolates cubic piecewise between the given points
/// this class is a wrapper to provide .NET XML Functions to the MathDotNet Library
/// </summary>
/// <param name="x">there are the supporting points</param>
/// <param name="y">the value at each supporting point. Must have the same length as the x-values</param>
public Spline(double[] x, double[] y)
{
//sort the values ascending
bool isAscending = false;
while (!isAscending)
{
for (int i = 1; i < x.Length; i++)
{
if (x[i - 1] > x[i]) //compare whether each value is bigger than the previous
{
for (int j = 0; j < i; j++)
{
if (x[j] > x[i]) //if the value at j is bigger than the value at i the correct position was found
{
//displace the value;
List <double> listX = x.ToList();
listX.Remove(x[i]);
listX.Insert(j, x[i]);
x = listX.ToArray();
List <double> listY = y.ToList();
listY.Remove(y[i]);
listY.Insert(j, y[i]);
y = listY.ToArray();
break;
}
}
break;
}
if (x[i - 1].Equals(x[i])) //if a X-value exists twice
{
throw new ArgumentException("LinearInterpolation: it is forbidden, that a X-value appears twice");
}
if (i == x.Length - 1) //if the loop has run to its end
{
isAscending = true;
}
}
}
this._x = x;
this._y = y;
spline = CubicSpline.InterpolateNaturalInplace(x, y);
}