spline - Script command – Ansys Optics

FDTD MODE DGTD CHARGE HEAT FEEM INTERCONNECT

Does a cubic spline interpolation of a data set.

Syntax

Description

out = spline(Ex,xold,xnew);

"not-a-knot" cubic spline interpolation of a 1D function.

Ex is an existing data set
xold specifies the points where Ex is sampled
xnew specifies new points to interpolate the data.

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.

Ex is an existing data set
xold specifies the points where Ex is sampled
xnew specifies new points to interpolate the data.
derivMin specifies the 1st-order derivatives at the starting point
derivMax specifies the 1st-order derivatives at the ending point

[[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));
derivMax = (Ex(end)-Ex(end-1))/(xold(end)-xold(end-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

List of commands , interp , plotxy

spline - Script command

Associated files

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