sparse matrix improvements in 2.9.x

[Shai Ayal]

Hi all,

I have to invert a sparse matrix using the "\" operator. This matrix is 
the result of a discretization of a Poisson equation using finite 
differencing. When I increase the resolution of the discretization above 
a certain threshold the inversion stops to work. I can currently invert 
a ~200x200 matrix, but not 300x300 derived from the same physical 
problem (i.e. I just decrease the cell size). I am almost sure this is 
not a memory problem (I have 1GB ram). So this is probably a numerical 
problem. It might be something in my discretization code, or in the 
inversion code.

I am currently using 2.1.72 with octave-forge. Should I upgrade to 
2.9.x? Is the sparse inversion there "better" in that it tries to do 
some clever decompositions (like matlab)?

Shai