[vtkusers] vtkArrayCalculator function definition syntax????

[Randall Hand]

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.

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......

On 4/14/06, W.T. Bridgman <William.T.Bridgman.1 at gsfc.nasa.gov> wrote:
>
> I want to do a cross product of two vector datasets.
>
> I  can't find any documentation (both the vtk list & Google) on
> vtkArrayCalculator or vtkFunctionParser to implement this.
>
> How would I code the SetFunction for this?  Does the parser recognize
> vector components?
>
> E[3]=V[2]*B[1]-V[1]*B[2], etc.
>
> 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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