Finding the peak position of a plot?

Hi,can anyone tell me how to find the peak of a plot . I have the code plot(sum(fill>0)); Now how to find the peak value of the plot??

[Sean de Wolski]

Don't overwrite the stock

fill

function

[Andrew Newell]

In other words, choose a different name for your variable FILL because it is the name of a MATLAB plot function.

Answer 1

[Andrew Newell]

If sum(fill>0) is the thing you want the maximum of, you could use

[C,I] = max(sum(fill>0));

The C give the maximum value (or values, if you have a matrix) and I the position(s).

[Niranjan]

All I need is to find the maximum position of the peak. Please have a look at the link for the figure.

https://picasaweb.google.com/lh/photo/4cX_xHOUkiW3GqBLe5XjdZOzMXS1UfqXPDW9N1lFu0w?feat=directlink

[Walter Roberson]

In your original problem statement, you asked to find the "peak value" of the plot, but now you are asking to find the "maximum position". The peak _value_ would be the maximum height, whereas the maximum position would be the x location at which it occurs.

Andrew's answer covers both possibilities: his C would be the height and his I would be the x value.

If all you need is the height, then you can simplify his code by a tiny bit,

C = max(sum(fill>0));

This really is about as fast as you are going to be able to get without resorting to mex, and since you only have about 120 columns I'm not sure you would be able to do any faster in mex (though you could do a mex version that used less memory.)

[Niranjan]

Thanks :)