How to stem positive part of wave?

Hi everyone,

I have a wave data, I need to show dispersion wave, so I need to "Stem" a "positive part" of the wave (look like the image below). Could you please to help me to solve it.

Thank you in advance.

Answer 1

[Prasad Kalane]

Try using following code

if true
  % code
endx1=rand(1,10);
x2=rand(1,10);
x=[x1 -x2];
subplot(121);stem(x);
title('+ve & -ve Data')
for i=1:length(x)
    if sign(x(i))==-1
        x(i)=0;
    end
end
subplot(122);stem(x);
title('+ve Data')

[vu ngothanh]

Thank you very much. It work perfectly.