Change the sign of column of imported file in matlab.

I have the data which is imported from notepad to matlab. it contains 2 columns and too many rows. one column of it is in negative which needs to be change its sign. Now how to change the sign of the entire column after impoteing the data in MATLAB?

Answer 1

[Ameer Hamza]

Something like this

M_new = M.*[-1 1]; % change sign of 1st column
M_new = M.*[1 -1]; % change sign of 2nd column

or

M_new = M*[-1 0; 0 1]; % change sign of 1st column
M_new = M*[1 0; 0 -1]; % change sign of 2nd column