MATLAB: How to extract specific data from a matrix

Question

Hi there,

I have a 100001×7 matrix that contains data, the first column is time and the other columns contain the values of some time-dependent functions at each time point. I would like to disregard the first 50000 rows and only look at the last part of the matrix in order to create a graph analyzing the period of one of the functions in Matlab. Could someone give me advice on how to do this? I know how to use ftt to analyse the period over all time points but not sure how to restrict it to just the last part.

Thanks, Scott.

Answer 1

You can use indexing to access any subset of an array:

>> X = rand(100001,7); % whole matrix
>> Y = X(50001:end,:); % from row 50001 to the last row

This is covered in MATLAB's introductory tutorials:

http://www.mathworks.com/help/matlab/getting-started-with-matlab.html