On Tue, May 8, 2012 at 11:15 AM, Lisandro Dalcin <span dir="ltr"><<a href="mailto:dalcinl@gmail.com" target="_blank">dalcinl@gmail.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
On 8 May 2012 12:04, Matthew Knepley <<a href="mailto:knepley@gmail.com">knepley@gmail.com</a>> wrote:<br>
> On Tue, May 8, 2012 at 11:00 AM, Christian Staudt<br>
> <<a href="mailto:christian.staudt@ira.uka.de">christian.staudt@ira.uka.de</a>> wrote:<br>
>><br>
>> Matthew Knepley <<a href="mailto:knepley@gmail.com">knepley@gmail.com</a>> wrote:<br>
>><br>
>> a) Is there an easy and efficient way to convert a numpy.ndarray to a<br>
>><br>
>> PETSc.Vec or PETSc.Mat (and vice-versa)? (A PETSc.Vec.getArray() returns<br>
>> a<br>
>><br>
>> numpy.ndarray, though I have found no such method for PETSc.Mat yet. )<br>
>><br>
>><br>
>><br>
>> If you are using dense matrices (MATDENSE) then MatGetArray() works.<br>
>><br>
>><br>
>> I don't think this is implemented in petsc4py: At least, there's no method<br>
>> PETSc.Mat.getArray()<br>
><br>
><br>
> If you ask Lisandro for it, he will put it in.<br>
><br>
<br>
Matt, I've never put that in just because I'm not sure how to make it<br>
general. PETSc have many different matrix formats, and MatGetArray()<br>
call is like a hack, where you can get very different things (the "1D"<br>
values of an AIJ matrix, the "2D" values of a dense matrix in Fortran<br>
order). What about MPIAIJ, what should I return to users? Can you<br>
suggest some approach or API to implement this (I mean, how to get<br>
arrays for the various matrix types)?</blockquote><div><br></div><div>I think the whole point is that you should not do it. However, that has never stopped us from giving users</div><div>what they ask for. We are not int he business of reforming computing practices, which is why we have</div>
<div>MatGetArray(). I would make a wrapper that failed unless the type was MATDENSE.</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Lisandro Dalcin<br>
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</font></span></blockquote></div><br><br clear="all"><div><br></div>-- <br>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>
-- Norbert Wiener<br>