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Lisandro Dalcin wrote:
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cite="mid:e7ba66e40709040720i791e1719s4e8015df168a1282@mail.gmail.com"
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<pre wrap="">On 9/4/07, Peter Schröder <a class="moz-txt-link-rfc2396E" href="mailto:ps@cs.caltech.edu"><ps@cs.caltech.edu></a> wrote:
</pre>
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<pre wrap="">Why not just construct the matrix without the corresponding columns and
rows? That preserves the symmetry (as it should of course), gives you a
smaller matrix, and you don't have the hassle with the zero columns.
</pre>
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<pre wrap=""><!---->
The former is far simpler in some contexts, and the size (of the
matrix) is not an issue if the appropriate MatOption is set regarding
sucessive assemblies.
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Yes. And of course I didn't really answer the original question...<br>
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cite="mid:e7ba66e40709040720i791e1719s4e8015df168a1282@mail.gmail.com"
type="cite">
<pre wrap="">I was discussing on petsc-dev about implementing a general object
PetscMapping. This would enable to set a general mapping on Vec's and
Mat's for using with {Vec|Mat}SetValues in order to 'filter and map'
indices, but this is a non-trivial feature that will require a fair
amount of time to implement.</pre>
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Such a thing could be very valuable. For example in active set
methods... I just ran into that and gave up (turns out that I was lucky
in that the Legendre dual of my energy is without constraints).<br>
<br>
Peter<br>
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