How to get exact position (red point)?

Please see the attached file. It is a time series plotted from a very long row vector (1x10000), and I want to locate the position (red point) where a "large" fluctuation occurs. Any MATLAB function or simple way to do it? Thanks.

Answer 1

[Orion]

If you know the "time zone" where you have this minimum, just use min on this interval.

something like :

[Value,Index] = min(YourTimeSeriesValues(2500:4500));

[Vic]

what if I have many such time series, and each of them has an unknown "time zone", and I wish to locate all red points in just one MATLAB program. Do you think it is possible?

[Vic]

and red points may be max or min...

[Orion]

Then you're gonna need to analyse the entire vectors.

see extrema, you'll get all the locals min and max.

But then, it's up to you to treat them the way you need it.