Sparse and Dense Matrixes

[Danesh_D]

Hi all,

I am wondering if ScaLAPACK has some additional types for Dense and Sparse matrices? I mean for example a large sparse matrix can be saved in a format to just eleminate zeros and save non-zero elements to save memory. Does ScaLAPACK support this?

Regards,

D.

[Julien Langou]

This is called sparse linear algebra and is not supported by LAPACK nor ScaLAPACK.
Libraries that supports sparse matrices are for example MUMPS for direct methods or
PESTc for iterative methods. They do save a lots of FLOPs and memory compared to
dense solvers.
For more libraries go at
http://www.netlib.org/utk/people/JackDongarra/la-sw.html
Julien.

[Danesh_D]

Thank Julian.
I would also like to know,

1. Is it possible to use two libraries like GMM++ and ScaLAPACK at the same time? Will it be efficient to be used on a parallel (grid) computer sysem?

2. What is difference between "direct" and "iterative" solvers?

Regards,

Danesh

[semihozmen]

For direct solvers you should search for explicit solvers which are generally used for linear system of equations. On contrary for iterative ones the synonym is implicit which means a nonlinearity occurs..