Plotting performance with cywin running under Win7

[Matthew Reich]

Hello Francesco Potortì,

Thank you for pointing to plotdecimate.  It will be useful.
However, for the task at hand, plot is significantly faster than using 
plotdecimate.  Given the size some data records, 10^4 to 10^7 elements, 
impressively fast.  And, without setting the RES parameter, decimation removes 
the very low duty cycle pulses which are important in the records.

Also, the main problem is unrelated to record size.  All plot windows turn gray 
after moving them, and sometimes after creating subsequent figures.  Convincing 
them to redraw usually takes some GUI interaction.  While redrawing rate scales 
with record size, the delay itself is not a significant problem. Disappearing 
window contents is the problem.

Any suggestions?

Thank you,
M.Reich


Matthew Reich:
>> Running Octave through cygwin under Win 7 or under XP, graphics 
>> performance for plotting suffers from slow GUI response speed. 
>> Following the suggestions in Octave documentation, I am using fltk 
>> rather than gnuplot, but the plotting speed and GUI response speed 
>> does not differ much between the two.  In particular, using fltk, the 
>> initial rendering is slow, especially for vectors over

Marco Atzeri:
>> several hundred thousand elements.
>
>the problem is the size, you need to trim down the number of points.

If you speak about simple 2-d plots, with x and y, you can use the plotdecimate 
function, in the plot package.  It removes the "useless"
points  before plotting, that is, those points which would not change the 
visual appearance of the plot.

It is intended to (greatly, in many cases) reduce the size of a plot saved in a 
vector format (like PS or PDF).  It will certainly also reduce the time needed 
to interactively generating a plot, but at the expense of time needed to 
decimate, so I don't know if it brings any advantages time-wise.

>> For plots of all data sizes, the window becomes gray when moved, 
>> after plotting another window, or intermittently after fltk GUI operations.
>> Convincing the window to redraw can take some time.  GUI response for 
>> zooming is slow and sporadic.

As far as these problems are concerned, you will certainly see an improvement 
using plotdecimate before plotting.

>> Also, any suggestions for which formats best export graphics for 
>> pasting into MSWord documents?

Generally speaking, vector formats are the best for plotting.  I use EPS.  In 
my experience, EPS is okay for MS word.

As a second choice, use a raster format with non-lossy compression.  PNG is the 
obvious choice in this respect.  Avoid lossy compression formats, like JPEG.

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