Moving plot of a sine wave.

Hi all,

Trying to create a moving plot of a sine wave. I'm essentially after the sine wave to start on the screen showing two cycles and then have the sine wave move while the plot moves to the right by two cycles and then back to the left by two cycles. I have this bit below to animate the sin wave but can't seem to get the plot to move as well. Cheers!

t = 0:0.1:4*pi;
y = sin(t);

for k = 1:length(t)
    plot(t(k),y(k),'x')
    hold on
    plot(t(1:k),y(1:k))
    axis([0 4*pi -1 1])
    grid on
    pause(0.1)
    if k ~= length(t)
        clf
    end
end

Answer 1

[Mrunmayee Gaikwad]

Hi,

To make the plot move, you will need to keep updating the ‘t’ vector in for/while loop and then plot the sine wave.

For example, this will move the plot to the right:

for j = 1:length(t) 
    plot(t,y) 
    axis([0 8*pi -1 1])   % moving 2 cycles would mean the end would be 4pi + 2*2pi = 8pi 
                          % you can keep the axis endpoints according to your need 
    grid on 
    pause(0.1) 
    hold on 
     if j ~= length(t) 
        clf 
     end 
    t = t + 0.1;  % used 0.1 increment as elements in t have 0.1 difference 
                  % Also, as y is already defined earlier, this change in t will not change y   
end 

To move to left you can vary j as: j = length(t):-1:1

[Harrison Seymour]

Hi Mrunmayee and thank you for your answer.

That is helping me to get the wave to move along the horizontal axis.

I was wondering though how to have the sine wave cycling while it moves along the axis. With your code the wave stays staionary and moves along the axis. I wanted the wave to cycle as well as move along the axis.

I will try and attach a file for a video for you to see what i mean.

No rush on the answer and thanks again.