extrema.m, extrema2.m

Search all extrema points of a time series or a surface with/without NaN's.

Description

Search all the maxima and minima points (peaks) in a time series (vector) or a surface (matrix), via columns, rows and crossing diagonals, ignoring NaN's elements.

USAGE:

[zmax,imax,zmin,imin]= extrema2(peaks);

where zmax (zmin) are the maxima (minima) elements and imax (imin) their linear index (check IND2SUB).

They come with the examples on the screenshot.

These are the same files as EXTREME.M and EXTREME2.M, but updated.

• Acknowledgements: This submission has inspired the following:; MinimaMaxima3D, Extrema
• MATLAB release: MATLAB 7 (R14)

[Sasha Trevizo]

The author sure had a headache after he finished this, so, thanks for avoid it to me! It works really good!

[cloves souza]

e muito legal

[JaeKyu Suhr]

This is excellent, but when i use extreme2.m
There is an error related to a variable "indx".
Therefore, I put a little bit of code in "extreme.m" like this

% NaN's:
inan = find(isnan(x));
if ~isempty(inan)
 indx = 1:Nt;
 indx(inan) = [];
 x(inan) = [];
 Nt = length(x);
%%----added code
else
    indx = 1:Nt;
%%%%%%%%%%%%%%%%
end

[Carlos Adrián Vargas Aguilera]

Thanks JaeKyu Suhr!, new file with bug fixed in about 1 day...

[Johnny Job]

Well done.

[Jacob Eisenstein]

thanks, very helpful.

[Dimitri Shvorob]

It might be helpful to briefly explain the exact definition of 'extreme points'.

[Carlos Adrián Vargas Aguilera]

You are so right Dimitri! I've made a terrible translation from spanish, I meant "extrema points"... Ouch! I need to change even the name!

[angeles sierra]

kiero agregar un linck a mi fotolog
 pero no se como aserle

[Yin Wang]

Excellent work, this is exactly what I need.

[joe saucer]

hey guys.. is their anyway for this program to just give me the biggest maxes? my plot has many, many small peaks.. also, can you store these as variables?

[Sanjeev]

Excellent work

[Rick Towler]

 

[Rick Towler]

Nice work.

[Rafael]

Perfect for finds maximun and minimuns in a surface! Great Job

[Aslak Grinsted]

Nice. There is also the built-in function findpeaks from the signal processing toolbox:

http://www.mathworks.se/help/toolbox/signal/findpeaks.html

[Onkar Singh Gujral]

 

[Thomas]

much better than findpeaks for my data thanks so much!

[Anusha]

Can someone help me on how to adapt this to detect maxima and minima points on an object edge?