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Hello !

I have to use the spline method to smooth my data curve.
I need to smooth data x and data z.

I use this link : C# Cubic Spline Interpolation[^]

I tried to integrate it in my code.

Here the part of the code which is concerned by the cubic spline interpolation : (in Void Start)

// To use Spline

x = new float[cpt-1];
y = new float[cpt-1];

for (int i = 0; i < cpt-1; i++) {
    for (int j = 1; j < names.Length+1; j++) {

        x[i] = nv_data[j-1].positions[i].x; // Data positions saved in text file
        y[i] = nv_data[j-1].positions[i].z; // Data positions saved in text file


    int n = 20;
    xs = new float[n];

    float stepSize = (x[x.Length - 1] - x[0]) / (n - 1);

    for (int i = 0; i < n; i++)

        xs[i] = xs[0] + i * stepSize;

// These two lines are not correct : CubicSpline and FitAndEval appear in red
CubicSpline spline = new CubicSpline();
float[] ys = spline.FitAndEval(x, y, xs);

I tried to declare it before Void Start :

public CubicSpline spline;

CubicSpline spline = new CubicSpline ();

But it's not good.

P-s : I put the other useful codes (CubicSpline, TriDiagonalMatrix, ArrayUtil) at the same location of this current code.

Thank you in advance
Updated 5-May-15 2:47am
Matt T Heffron 5-May-15 13:57pm    
The first thing I noticed is that your loading of the x and y arrays is clearly wrong.
Every iteration of the inner, j loop, overwrites the preceding values in the x[i] and y[i] locations.
If the values you are using for the spline aren't what you think they are, then the resultant spline will not be what you expect.
Coralie B 6-May-15 1:56am    
All data of nv_data[j-1].positions[i].x and nv_data[j-1].positions[i].z won't be saved in x[i] and y[i] ?
Matt T Heffron 6-May-15 12:38pm    
Nope, each of the x[i] can hold a single float value (likewise y[i]).
Each iteration of the for (int j = ... loop assigns the different values of nv_data[j-1].positions[i].x to the same x[i] location, overwriting the previous value there.
Use the "Improve question" (above) to describe what you are trying to do and more people will be able to help.

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Coralie B 5-May-15 8:37am    
Thank you but can you help me more please ?
I'm going to update my question

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