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Re: Octave's plotting much slower than matlab

From: Thomas Ilnseher
Subject: Re: Octave's plotting much slower than matlab
Date: Mon, 21 Jan 2008 14:56:06 +0100

Am Montag, den 21.01.2008, 14:17 +0100 schrieb David Bateman:
> Doesn't surprise me given the way that Octave is constrained to
> communication with gnuplot for the scatter function. Each point is a
> patch object with a single point, and so Octave sends a full gnuplot
> plot command to the gnuplot process for each and every point in the
> scatter plot.. I suspect that this is one function that will be vastly
> accelerated by the change to a different graphics backend. However, it
> doesn't appear that JHandles handles the patch with a single point or
> unclosed patches, and so its no use for your case.. All I can offer
> is,
> we're working on it..
Well ... 

I changed the function to this:

f=fopen('scatter.txt', 'r');
[v c] = fscanf(f, '%d', [2, inf]);
%scatter(v(1,:), v(2,:));
plot(v(1,:), v(2,:), 'ob');

now the stuff is even _faster_ than matlab, as I pointed out before.
the output is roughly the same as with scatter (except that all circles
have the same  color). by doing some tricks with "hold('on');" and
sub-ranges, I can even get the same picture as with scatter. 

I definitely do not need to access specific points as patch objects.

So I'm fine (and might write myself a fscatter.m file). 

Thomas Ilnseher <address@hidden>

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