Subject: [FFC-dev] define a "diagonal" form

From: "Alessio Quaglino" <[email-masked]>
Date: Wed, 19 Sep 2007 19:19:39 +0200 (CEST)

I'm wondering if it's possible to tell FFC that he doesn't have to test
all the basis functions against each other, but only against themself
once, so that I get only the diagonal terms of the matrix. I guess this
would speedup *a lot* the assembly in the case of piecewise elements
having support on only one tetrahedra, or the case when you need only
diagonal elements. Am I right or this special case is already handled? Can
I use a special notation to achieve this aim? Thanks.

Alessio

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From: Anders Logg <[email-masked]>
Date: Thu, 20 Sep 2007 00:20:55 +0200

I think this is already handled. The code generated by FFC is optimized 
so that things that are known to be zero a priori are never computed.

Try the simplest possible example you can think of and look at the 
generated code (the function tabulate_tensor) and see if this is 
correct. (And let us know what you find.)

/Anders

Alessio Quaglino wrote:
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