On Sat, Sep 13, 2014 at 11:52 AM, William A Stein <wst...@uw.edu> wrote:
> On Sat, Sep 13, 2014 at 11:28 AM, Erik Slivken
> <> wrote:
>> William-
>>
>> I am trying to find the eigenvalues of a roughly 10000x10000 sparse matrix
>> with entries from {0,1} (and would like to do this for even larger
>> matrices). I don't know what could be done to increase the speed (right now
>> it has been running for roughly half a day). But it said to email you to
>> raise a quota. Also, if there is special faculty access, this is a project
>> with Chris Hoffman from UW and I am sure he would sign on for more computing
>> power.
>>
>> Thanks for your time.
>>
>> Cheers,
>> Erik Slivken
>>
>> P.S. How long should it take to find the eigenvalues of a 10000x10000
>> sparse matrix with entries from {0,1}? What about a 10^6x10^6 sparse matrix
>> with entries in from {0,1}?
>
> Never. Sage doesn't have any easily available sophisticated sparse
> linear algebra algorithms, as far as I know. Linbox (which is in Sage
> -- a C++ library), might have something; and Cremona's eclib has some
> gems hidden in it. I wrote some really stupid sparse linear algebra,
> which was sufficient for something I did once. There's several
> stages to sparse algorithms, and what is in Sage only implements the
> first part -- the "endgame", which is to solve a resulting dense
> system at a certain point, isn't in sage. Sebastian Pancratz and I
> did implement it once
> somewhere... (not sure), but it isn't in sage (and it was not easy),
> and now Sebastian works at a bank.
>
> Try typing
>
> set_verbose(2)
>
> to see what is happening, if you're using sage.
>
> You should seriously consider searching the web for current available
> software for sparse linear algebra. Last I checked, unfortunately,
> Sage is definitely not an off-the-shelf solution for anything
> nontrivial involving sparse matrices, except for maybe efficiently
> storing them.
>
> (I've changed the subject and cc'd some people on this email, in case
> anybody knows anything about sparse linear algebra and wants to chime
> in.)
He adds "Also, I only need the largest eigenvalue, if that makes it easier."
>
> William
>
> --
> William Stein
> Professor of Mathematics
> University of Washington
> http://wstein.org
> wst...@uw.edu
--
William Stein
Professor of Mathematics
University of Washington
http://wstein.org
wst...@uw.edu
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