Question concerning usage of cscvn and fnplt

Hello everybody,

I'm trying to fit a spline to a set of data. I use a loop to vary the interval at which i'm using data, this is denoted by the 1:i:end. My data looks like this:

      0         0   -0.2000
    9.8500   -0.0100   -1.9500
   19.7100   -0.0100   -3.6100

I am using the following command to generate a spline

Spline(i) = struct(cscvn([Coord(1,1:i:end); Coord(2,1:i:end);Coord(3,1:i:end)]));

In which the first columns contains x values, the second y, and the third z. If I then try to recreate the data which I tried to fit I use

Points(i).a = fnplt(Spline(i));

I used these two commands right after each other, so without any manipulation. However, I found that the data, as stored in Points(i).a contains some multiples, so repeating pairs of x,y,z data. I've found out that every two points, it shows a repeating entry, an example is:

        0         0   -0.2000
    4.9039   -0.0061   -1.0789
    9.8098   -0.0100   -1.9430
    9.8500   -0.0100   -1.9500
    9.8500   -0.0100   -1.9500
   14.7193   -0.0105   -2.7813
   19.6322   -0.0100   -3.5972
   19.7100   -0.0100   -3.6100
   19.7100   -0.0100   -3.6100

I notice that all the values that are given in input data are multiplied, and the 'interpolated' values only come up once. Is this a result of the piecewise nature of the spline fitting, or is there some cause in the way I'm using the cscvn?

Thanks in advance for your time!

Roy