Documentation

This is machine translation

Translated by Microsoft
Mouse over text to see original. Click the button below to return to the English verison of the page.

Postprocessing Splines

You can use the following commands with any example spline, such as the cs, ch and sp examples constructed in the section Cubic Spline Interpolation.

First construct a spline, for example:

sp = spmak(1:6,0:2) 

To display a plot of the spline:

fnplt(sp) 

To get the value at a, use the syntax fnval(f,a), for example:

fnval(sp,4)

To construct the spline's second derivative:

DDf = fnder(fnder(sp))

An alternative way to construct the second derivative:

DDf = fnder(sp,2);

To obtain the spline's definite integral over an interval [a..b], in this example from 2 to 5:

diff(fnval(fnint(sp),[2;5]))

To compute the difference between two splines, use the form fncmb(sp1,'-',sp2), for example:

fncmb(sp,'-',DDf);
Was this topic helpful?