Re: Real-time plots under X11/Exceed

[Daniel J S. <dan...@ie...>]

pa...@mi... wrote:

>Daniel,
>Thanks for your reply.
>

You're welcome.

>What I am trying to do is to replot simple time series file every second
>(or every update whichever is less frequent). The file would look like 
>12:44:51 GOOG.O +193.00 
>12:44:52 GOOG.O +193.058 
>12:44:53 GOOG.O +193.95 
>.....
>and although file can be large (several thousand lines) the performance
>issue is not
>in just gnuplot itself (which takes about 10% of CPU), bbut gnuplot_x11
>that takes upto 20% and crashes my Exceed emulator of X. So I would
>think that objective is to reduce
>amount of data  sent to:
>

Well, several thousand lines is starting to get up there.  It would 
probably work on the setup Ethan described.  However, when you think of 
a video screen, it's what?  Maybe 800x1200?  Several thousand lines 
would mean each line averaging the space of a pixel.  In other words 
both gnuplot and gnuplot_x11 are doing a lot of number crunching to 
compute at a resolution that ends up being discarded.  (Unless you are 
going to do zooming!!  But in real time that's a big if.)  So reducing 
that data up front might help.  You can't just discard data points for 
fear of aliasing, perhaps something like averaging of the samples, i.e., 
reduce 2000 points to 200 points by averaging groups of ten.  (I'm 
talking uniform sampling now.)  Just a thought.

Dan