Does a cubic spline interpolation of a data set.
Syntax 
Description 

out = spline(Ex,xold,xnew); 
"notaknot" cubic spline interpolation of a 1D function.
The points in xnew do not have to be within the bounds of xold. 
spline(Ex,xold,xnew,[derivMin; derivMax]); 
"clamped cubic spline" interpolation of a 1D function.

[[NOTE:]] The [[spline]] script has been modified in version 2020R2 or later. To recover the result from previous versions, use the "clamped cubic spline" option and define the "derivMin" and "deriveMax" as follows: derivMin = (Ex(2)Ex(1))/(xold(2)xold(1)); 
Example
Resample Ex at xnew using cubic spline and linear interpolation methods. Note that xnew is outside the bounds of xold.
xold=linspace(0,10,7); Ex=sin(xold); xnew=linspace(1,9,25); # defining a new x vector Exnew=interp(Ex,xold,xnew); # interpolating the new data set Exnew2=spline(Ex,xold,xnew); # smoothing plotxy(xold,Ex,xnew,Exnew,xnew,Exnew2,"x","y",""); legend("old data", "interp", "Spline");
The example code will generate the following plots, displaying the difference between the linear and cubic spline interpolation techniques.
See Also