how to select and save particulat part of a column in mat file?

I have saved a CSV file as mat file and I could read it. the file has many column and each column has thousands of rows.

How can I access and select particular column and sets of rows of these column and save it as matfile?

mydata=readmatrix('TEST.csv');

Answer 1

[Turlough Hughes]

columns = [2 3 5];
rows = 50:100;

x = mydata(rows,columns);
save('mydata.mat','x')