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pink
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Why is plot3 slow when I use it in a loop?

Asked by pink
on 8 Jun 2011
I create plot3 in gui axes, if the number of elements that the many depictions of the process is very slow, if you can provide solutions
for i=1:length(AX(:,1))
plot3(AX(i,:),AZ(i,:),AY(i,:),'-c','LineWidth',0.25);
hold on
plot3(AXD(i,:),AZD(i,:),AYD(i,:),'-g','LineWidth',0.5);
end

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2 Answers

Answer by Andrew Newell
on 8 Jun 2011

You could try using line instead of plot3. You'll have to make sure all your options come in pairs, e.g.,
line(AX(i,:),AZ(i,:),AY(i,:),'LineStyle','-','Color','c','LineWidth',0.25);
See linespec for how to define each property.
EDIT: With the data you provided, I tried these commands and it worked fine.
for i=1:size(AX,2)
line(AX(i,:),AZ(i,:),AY(i,:),'LineStyle','-', ...
'Color','c','Marker','.','LineWidth',1)
line(AXD(i,:),AZD(i,:),AYD(i,:),'LineStyle','-', ...
'Color','g','Marker','.','LineWidth',1)
end
On my machine this is 4 times faster than using the code you provided. Note that when you use line the image is saved by default, so you don't need hold on.

  11 Comments

is work
sorry, but the picture does not fit what I want
object generated using the "plot3" not the same as using the "line"

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Answer by Walter Roberson
on 8 Jun 2011

You only need to execute the "hold on" once; after that it is set and becomes a waste of time.
At some point, you are going to exceed the amount of memory that your graphics card has easily available; things will slow down then.
You could experiment with switching renderers.

  6 Comments

Yes, that could help:
axh = gca;
plot3(axh, AX(1,:),AZ(1,:),AY(1,:),'-c','LineWidth',0.25);
hold(axh,'on')
plot3(axh,AXD(1,:),AZD(1,:),AYD(1,:),'-g','LineWidth',0.5);
for i = 2:length(AX,2)
plot3(axh,AX(i,:),AZ(i,:),AY(i,:),'-c','LineWidth',0.25);
plot3(axh,AXD(i,:),AZD(i,:),AYD(i,:),'-g','LineWidth',0.5);
end
Should be size(AX,1) instead of length(AX,2)
AX =[ 0 2.1213;
4.2426 2.1213;
4.2426 2.1213;
0 2.1213]
AY =[ 0 4000;
0 4000;
0 4000;
0 4000]
AZ =[-4.2426 -2.1213;
-4.2426 -2.1213;
0 -2.1213;
0 -2.1213]
AXD =[ 0 2.0900;
4.2426 2.0900;
4.2426 2.0900;
0 2.0900]
AYD =[ 0 3.6818;
0 3.6818;
0 3.6818;
0 3.6818]
AZD =[4.2426 2.1849;
4.2426 2.1849;
0 2.1849;
0 2.1849]

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