[vtkusers] vtkArrayCalculator function definition syntax????

[Randall Hand]

Well, from checking the CVS records of that file (
http://public.kitware.com/cgi-bin/viewcvs.cgi/Common/vtkFunctionParser.cxx?rev=1.32&view=log)
it hasn't been updated in over a year.  Since my changes are just
slight
modifications to that file, I would think odds are good that it will run
with 4.4 no problem.

Of course, YMMV but it's worth a shot :)

On 4/17/06, W.T. Bridgman <William.T.Bridgman.1 at gsfc.nasa.gov> wrote:
>
>
> On Apr 14, 2006, at 2:08 PM, Randall Hand wrote:
>
> > Unfortunately, VTK's array calculator does not support true cross
> > product computation.  I have a patch in bug 2903 ( http://
> > www.vtk.org/Bug/bug.php?op=show&bugid=2903&pos=19 ) that adds a
> > "cross(X,Y)" function, but it hasn't been integrated yet.  You can
> > probably grab it & replace your vtkFunctionParser with it and it'll
> > work.
>
> Is it v5.0+ only?  Currently I must build VTK with another module
> that will (currently) not run beyond v4.4.
>
> > In the meantime, you've got 2 options:
> >    1) Load your vectors in a 3-scalars, and then perform the cross
> > product yourself as you've shown.
> >    2) Use V.ihat, V.jhat, and V.khat to access the 3 components
> > (read: Vector dot i-unit vector, etc)
> >
> > also, you can't directly write back the results into components..
> > So you'll have to compute each component & multiply by ihat/jhat/
> > khat and then add the 3 parts together... It's gonna be one massive
> > & messy function line.  And slow to run......
>
> I may examine this as an interim solution.  Hopefully the other code
> will get updated to v5+ soon.
>
> Thanks,
> Tom
> --
> Dr. William T."Tom" Bridgman               Scientific Visualization
> Studio
> Global Science & Technology, Inc.          NASA/Goddard Space Flight
> Center
> Email: William.T.Bridgman.1 at gsfc.nasa.gov  Code 610.3
> Phone: 301-286-1346                        Greenbelt, MD 20771
> FAX:   301-286-1634                        http://svs.gsfc.nasa.gov/
>
>
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