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[IDV #PKQ-297414]: Laplacian formula "lap(S)" fails. An apparently equivalent version created locally doesn't.

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  • Subject: [IDV #PKQ-297414]: Laplacian formula "lap(S)" fails. An apparently equivalent version created locally doesn't.
  • Date: Sat, 14 Sep 2013 10:10:07 -0600
> Full Name: Dave Dempsey
> Email Address: address@hidden
> Organization: San Francisco State University
> Package Version: 4.1 build date:2013-08-02 18:38 UTC
> Operating System: Mac OS X
> Hardware: Java: home: 
> /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home version: 
> 1.6.0_51 j3d:1.5.2 fcs (build4)
> Description of problem: Creating display: Contour Plan View
> TypeError: div() takes exactly 1 argument (2 given)
> org.python.core.PyException
> 
> I'm calculating the Laplacian of 500 mb heights from the NAM model (just to 
> see if I can do it). To do this, I created a new formula, called "Laplacian 
> operator", and put it in the Grids group. It is defined simply as "lap(S)". 
> The formula "lap(S)" is defined in the Java formula library.
> 
> Applying the new formula to a NAM 500 mb height field and trying to plot 
> contours of it produced the error message above.
> 
> For reference: lap(S) is defined in the Jython library as 
> div(ur(grads),vr(grads)), where grads = grad(S) and S is a scalar field.
> 
> In turn, div is defined as add(ddx(ur(V), ddy(vr(V)), where V is a vector 
> field.
> 
> Then, I tried creating my own Laplacian operator formula. It bypasses the 
> "div" formula and calculates the Laplacian from
> a scalar field directly, although it appears to use the same formula as 
> lap(S) and
> 
> add(ddx(ur(grad(S))),ddy(vr(grad(S))))
> 
> Unlike lap(S), this works.
> 
> So, why would lap(S) fail where my algorithmically equivalent version 
> succeeds?

Dave,
    I think your equivalent version is corrected. The problem with the original 
lap(S) is that it should call div(grads) or add(.....).   I will fix it now.


Yuan
> 
> I've attached a bundle that creates a plot using the successful version of 
> the Laplacian operator (called "Laplacian operator" in the Grids group of 
> forumulas).
> 
> -- Dave
> 
> 
> 
> 
> 
> ******************
> Stack trace:
> Traceback (most recent call last):
> File "<string>", line 1, in <module>
> File "<string>", line 208, in lap
> TypeError: div() takes exactly 1 argument (2 given)
> 
> 
> 


Ticket Details
===================
Ticket ID: PKQ-297414
Department: Support IDV
Priority: Normal
Status: Open