How to display the max values of a given interval

I have a program that plot a graph. This graph is like a senoidal curve.

1) I need get the 3 maximum and minimun values of this graph, excluding the highest value.

2) I need too, display the max of a determined interval.

3) And last of all, i need to do the x axis of the graph present more values.

Anybody can help me?

Answer 1

[Azzi Abdelmalek]

doc max
doc min
doc findpeaks

Answer 2

[Rahul punk]

m = [7;1;4;4;12;2;6;10;2];

[temp,originalpos] = sort( m, 'descend' );

n = temp(1:3)

p=originalpos(1:3)