[Paraview] Calculator and vector products

[Dan Goldstein]

Am I correct that the cross() operation is still broken in ParaView  
3.4.0
related to the bug posted: http://www.gccxml.org/Bug/view.php?id=2903 ?

randall.hand once suggested the addition of the support for the vector  
cross product operator. It was added some time later. Then some new  
operators such as boolean ones were added and during this process  
unfortunately the vector cross product operator was carelessly  
disabled due to the incorrect check on the number of the input  
parameters.

The correct format of a vector cross product operation is:

     ====================================
     vector_C = cross(vector_A, vector_B)
     ====================================

     INSTEAD OF

     ====================================
     cross(vector_A, vector_B, vector_C)
     ====================================

     In other words, there should be TWO parameters and ONE comma.

     However, the bug in vtkFunctionParser:: CheckSyntax() occurred  
within the following segment (between line 1444 and line 1453):

     ============================================================
     if ((functionNumber == VTK_PARSER_MIN) ||
         (functionNumber == VTK_PARSER_MAX))
       {
       expectCommaOnParenthesisCount[parenthesisCount+1] = 1;
       }
     if ((functionNumber == VTK_PARSER_IF) ||
         (functionNumber == VTK_PARSER_CROSS))
       {
       expectTwoCommasOnParenthesisCount[parenthesisCount+1] = 1;
       }
     ============================================================

     Now this segment has been replaced with

     ============================================================
     if ((functionNumber == VTK_PARSER_MIN) ||
         (functionNumber == VTK_PARSER_MAX) ||
         (functionNumber == VTK_PARSER_CROSS))
       {
       expectCommaOnParenthesisCount[parenthesisCount+1] = 1;
       }
     if (functionNumber == VTK_PARSER_IF)
       {
       expectTwoCommasOnParenthesisCount[parenthesisCount+1] = 1;
       }
     ============================================================

     Now the code performs correct check on the input format in terms  
of vector cross product and the suggested functionality is supported.

       Thanks for suggesting the enhancement.

       new revision: 1.43; previous revision: 1.42
It says it is fixed but it seems to exhibit the behavior  described it  
the history of this bug (in 3.4.0). Namely if you give it two  
arguments it complains
about needing three? Is this fixed in the cvs version?

Thanks

Dan

On Mar 4, 2009, at 4:23 PM, Jacques Papper wrote:

> Thanks for the answer. I guess I missed the cross button !
> (The whole point was that I didn't want to write out the cross  
> product anymore !! :)
>
> 2009/3/4 Scott, W Alan <wascott at sandia.gov>
> Silly me, of course.  Math class was just too many years ago.
>
> alan
>
> -----Original Message-----
> From: Pebay, Philippe P
> Sent: Wednesday, March 04, 2009 2:59 PM
> To: Scott, W Alan; 'Jacques Papper'; 'paraview'
> Subject: RE: [Paraview] Calculator and vector products
>
> Hello
>
> The + sighs between cross terms should be replaced by - signs as  
> follows:
>    i ( a_2b_3 - a_3b_2 )
>  + j ( a_3b_1 - a_1b_3 )
>  + k (a_1b_2 - a_2b_1 )
>
> P.
>
> --
> Philippe Pébay
> Sandia National Laboratories
>
> ________________________________________
> From: paraview-bounces at paraview.org [paraview-bounces at paraview.org]  
> On Behalf Of Scott, W Alan [wascott at sandia.gov]
> Sent: Wednesday, March 04, 2009 1:30 PM
> To: 'Jacques Papper'; 'paraview'
> Subject: Re: [Paraview] Calculator and vector products
>
> I don't know if this is correct, but I took a quick attempt at  
> making a cross product.  I am using the dataset can.exo.  In the  
> calculator, I am trying to create the cross of the DISP and ACCL  
> vectors.  Here is the formula:
>
> iHat*(DISPL_Y*VEL_Z+DISPL_Z*VEL_Y)+jHat*(DISPL_X*VEL_Z+DISPL_Z*VEL_X) 
> +kHat*(DISPL_X*VEL_Y+DISPL_Y*VEL_X)
>
>
>
> Alan
>
> -----Original Message-----
> From: paraview-bounces at paraview.org [mailto:paraview-bounces at paraview.org 
> ] On Behalf Of Jacques Papper
> Sent: Wednesday, March 04, 2009 12:27 PM
> To: 'paraview'
> Subject: [Paraview] Calculator and vector products
>
> I am trying to do a vector product with the Calculator, but this  
> seems to fail "Error deciding between ambiguous operators".
> Is there a way to do vector products ? Or is this something that  
> needs to be implemented ?
>
> Jacques PAPPER
> Applied CFD Team Leader
> Tel: +44 (0) 1234 324677
>
>
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