Re: ITSOL interface

[c.]

On 10 Jul 2013, at 15:03, Kai Torben Ohlhus <address@hidden> wrote:

> On 10 July 2013 14:42, Nir Krakauer <address@hidden> wrote:
> Kai--
> 

>  and then the last point on my list before the midterm is like you say ZITSOL 
> (which includes ILUK, ILUT and ILUTP in complex versions) and the 
> comprehensive test cases.
> 
> Kai

Hi Kai,

Actually I think it is a good idea to not wait until the very end of the 
project to start looking at the test cases.
Which makes me think that I had promised you to provide a simple way to 
generate automatically matrices for testing your preconditioners, 
so here is a quick example:

-------------------------------------
pkg load bim

n = 50;

%% set beta = 0 for SPD matrix
beta = 1e4; 

msh = msh3m_structured_mesh (n, n, n, 1, 1:6);
inodes = setdiff (1:columns (msh.p), bim3c_unknowns_on_faces (msh, 1:6));
x = msh.p(1,:) .';
A = bim3a_advection_diffusion (msh, 1, 1, 1, beta*x);
b = bim3a_rhs (msh, 1, 1);

%% the matrix to factorize is the one below
A = A(inodes, inodes);

%% solve the system by GE forcomparison
%% n = 80 is already to large to do this on my system;
b = b(inodes);
u = 0*x;
u(inodes) = A \ b;
-------------------------------------

for beta = 0 the matrix will be SPD and its condition number should scale as 
n^2 
otherwise it will be unsymmetric.

n = 80 is already too large to handle via mldivide on my system it'd be very 
interesting in to know the maximum size of system you can deal with by ilu+pcg 
or ilu+gmres.

Also, what's your plan about ichol?

c.