[Octave-bug-tracker] [bug #31305] slow contour plot

[David Bateman]

Update of bug #31305 (project octave):

                  Status:               Need Info => Fixed                  
             Assigned to:                    None => dbateman               
             Open/Closed:                    Open => Closed                 

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Follow-up Comment #36:

Ben, with your "axis tight" fix, I now have both contour and contourf working
correctly with the FLTK backend. So I decide to push this patch as you
suggested. See the changeset

http://hg.savannah.gnu.org/hgweb/octave/rev/c0a95a5c6d25

With this patch contour(rand(10)) is four times faster than it was previously
on my machine and the hggroup::adopt function now has O(1) behavior rather
than O(N) (where N is the number of contours already plotted). This being
called when every contour is added to the contourgroup, this means that the
speed should be even faster with larger contourgroups like the original
authors case and that __contour__ should have O(N) speed rather than the
O(N^2) it had previously.

However I don't understand the need for zlim to be set. The contours are
plotted in 2D and so zlim should be ignored by the backends. Can you please
explain? Though I suggest we close this bug report as we've addressed the
original issue (and a few others in passing), so please start a new bug
report.

D.


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