[Octave-bug-tracker] [bug #55642] isosurface is slow

[Michael Leitner]

Follow-up Comment #7, bug #55642 (project octave):

Thank you, Guillaume, for applying the principle to the helper function.
Actually, last night I was also active. I attach a version of
__unite_shared_vertices__.m that is now perhaps a bit more efficient because
the faces are updated only once, and I have now a tolerance criterion that
should be the tightest possible (it is now again vector-valued). And further,
it is stable in the sense that the order of vertices as they are returned is
the same as they were provided. This was not the case with my previous
version, but it was the case with Markus' initial version, and this was a
condition for his deletion of facevertexcdata to work. If you add the lines at
the end


dum=true(size(lut));
dum(J)=false;
J=dum;


then you should be able to use this as a drop-in replacement for the previous
version. More efficient would be to return J as it is and select the
corresponding elements from facevertexcdata (then it would be more flexible if
in the future this function is used for other purposes), or as you did it to
pass it in and out and select from it in the loop.

Rik, sorry, I am doing this here on Octave 4.0.3 (greetings from Debian
Stable) by pulling in the relevant .m-files from the web repository. I do not
have a full mercurial set-up here so that I could prepare a changeset.

(file #46213)
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Additional Item Attachment:

File name: __unite_shared_vertices__n.m   Size:1 KB
    <https://savannah.gnu.org/file/__unite_shared_vertices__n.m?file_id=46213>



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