Telling MATLAB to wait

I'm doing a project and when I run my code, instead of MATLAB plotting the results after every time-step, it's only plotting the end result. I tried using the wait and timeout function but was unsuccessful. If anyone could help me put a 0.5 sec delay so MATLAB has the chance to plot that would be great!

Answer 1

[Matt Fig]

Do you call PLOT after every time-step? After every time-step, call PLOT then cal DRAWNOW. You can also call PAUSE with a time-to-pause argument, but I doubt this is what you really want to do with your code.

[Zach]

thank you!

Answer 2

[Sean de Wolski]

pause(0.5)

[Doug Hull]

To flush the graphics queue, DRAWNOW is preferred.

[Zach]

thank you!

[Sean de Wolski]

Yes, but if only drawnow is used then it'll still zip right through and show only the end result. Hence is they want to see each time point, a pause() is still necessary.

[Sean de Wolski]

x = 1:10;

y = x.^2;

figure;

hold on

for ii = 1:10

plot(x(ii),y(ii),'r*');

drawnow;

pause(0.5) %comment me to see the difference

end

[Matt Tearle]

Well, it's not showing only the end result, it's just that it's too quick for the eye to catch the intermediate steps.

Sorry, I'm a pedant. But the bottom line is correct: use drawnow to flush the queue *and* (usually) pause to control the animation timing.

[Matt Fig]

Also, it would depend on what the user meant by timestep. I was picturing a lengthy calculation that would allow for more of a natural pause using DRAWNOW.

Also, setting the axis limits at the start is always a good idea for these types of things!

x = 1:10;

y = x.^2;

figure;

axis([0 10 0 100])

hold on

for ii = 1:10

plot(x(ii),y(ii),'r*');

sort(rand(3000)); % Simulate lengthy calculation

drawnow;

end

[Matthew Simoneau]

FYI, I opened up a related discussion in a new question: http://www.mathworks.com/matlabcentral/answers/7309-is-pause-a-superset-of-drawnow

[Jiro Doke]

@Matt Tearle,

I don't believe that "it's just too quick for the eye". I think it's because of the event queue issue. In other words, if you were to record the screen with a high-speed camera, you probably still won't be able to see the intermediate plots.

Unfortunately, I don't have a high-speed camera handy so I can't verify...

[Matt Fig]

@Jiro and Matt Tearle,

I can see the intermediate plots if the ax-lims are held before the loop! Perhaps I need a faster computer...

[Jiro Doke]

@Matt Fig,

You mean without "drawnow"??

@Matt Tearle,

Darn hidden comments. I think I didn't see the whole thread of comments, so I thought you were referring to the OP's question, not to Sean's comment.

[Matt Fig]

@Jiro,

I mean the code I pasted in comment 6, but without the call to SORT. It is fast, but I definitely see it changing...

My new laptop should be here tomorrow, so I may not see it then.

[Jiro Doke]

@Matt Fig,

Oh, I see. Yeah, I also see it with the drawnow. The question is whether it's updating faster than 30 Hz. My monitor refreshes at 60 Hz, so Nyquist frequency is 30.

[Matt Tearle]

Thanks, Jiro. I think you've just made a business case for me needing a new computer... :)

[Ghenam Dahmane]

thanks so match