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Local maxima and minima of a pp spline

version 1.2 (2.02 KB) by

Determine the locations of local maxima and minima in a pp spline generated by pp = spline(x,Y);

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This function uses vectorised methods to determine the locations of maxima and minima where they exist within a piecewise spline fit. The matlab built-in functions for determining the maxima and minima, by differentiating the pp spline and finding its zeros (using the Spline toolbox), are quite slow, and are given as comment at the end of the m-file for reference.

Comments and Ratings (4)

Darik

Darik (view profile)

Much faster than fnmin -- exactly what I was looking for. Thanks a lot!

Thomas Clark: Adjusted as suggested.

Actually I adjusted it a while ago, but I forgot to thank you - thanks.

Ah!

Apologies - the code itself is actually spline toolbox independent - but the example code requires fnval, which can be directly replaced with ppval for non spline-toolbox users.

Suggest updating the example - I've updated my rating!

Cheers

Tom

Tom Clark

The following link contains a short piece of code which makes this submission toolbox-independant (derivation of a pp).

http://orion.math.iastate.edu/alex/471/Examples/kincaid-cheney/matlab/ppder.m

Kind regards

Tom

Updates

1.2

Altered the example code so that it is also toolbox independent.

MATLAB Release
MATLAB 7.7 (R2008b)

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