Re: Sparse matrices

[Carlo De Falco]

Please keep the list in CC and use bottom posting [1] when replying to messages.

> On 5 Mar 2017, at 19:09, Clinton Winant <address@hidden> wrote:
> 
> Thanks  I want to try sparsersb.  To do this I suppose I ned to rebuild 
> octave with a flag such as --with-sparsersb??

No, what made you think such flag exists?

>  Should I also remove sparsesuite from my system??

No.

Here is the instructions for installing packages:
https://www.gnu.org/software/octave/doc/interpreter/Installing-and-Removing-Packages.html#Installing-and-Removing-Packages

Be aware that sparsersb WILL NOT transparently improve performance of exixsting 
Octave code,
your code will have to be explicitely written to use sparserb and an 
appropriate iterative solver.

Actually, what sparsersb really does is just provide a special class of 
matrices for which matrix vector product 
can be computed very fast.

Also be aware that for small size matrices (i.e. whose full LU factorization 
would fit in memory) 
the direct solvers from suitesparse will most likely always perform better than 
an iterative solver, 
especially if you don't have a good preconditioner.

On the other hand iterative solvers are able to solve systems of very large 
size that would lead to memory overflow
with a direct method.

c.

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