help-octave
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Splines


From: Carlo de Falco
Subject: Re: Splines
Date: Wed, 1 Oct 2008 11:44:37 +0100


On 01/ott/08, at 10:56, Jaroslav Hajek wrote:


The interp1 functions *are* using splines when you specify "cubic"
interpolation.
not really, try...

>> x = sortrows (rand(10,2));
>> xsp = linspace(min(x(:,1)), max(x(:,1)), 100);
>> plot(x(:,1),x(:,2),'x', xsp, interp1(x(:,1), x(:,2), xsp, 'cubic'), xsp,spline(x(:,1), x(:,2), xsp))

I think

spline(x(:,1), x(:,2), xsp)

is rather equivalent to

interp1(x(:,1), x(:,2), xsp, 'spline')

>> norm (spline(x(:,1), x(:,2), xsp) - interp1(x(:,1), x(:,2), xsp, 'spline'), inf)
ans = 0

but the spline command gives more control on the boundary slope...


To get a denser sample, you can add
x = linspace (min(x), max(x), 1000).';
or something similar after the `x = unique' line.

c.



reply via email to

[Prev in Thread] Current Thread [Next in Thread]