# Gmm library¶

## Description¶

Gmm++ is a template linear algebra library which was originally designed to make an interface between the need in linear algebra procedures of GetFEM and existing free linear algebra libraries (MTL, Superlu, Blas, Lapack originally). It rapidly evolves to an independent self-consistent library with its own vector and matrix types. It is now used as a base linear algebra library by several other projects.

However, it preserves the characteristic to be a potential interface for more specific packages. Any vector or matrix type having the minimum of compatibility can be used by generic algorithms of Gmm++ writing a linalg_traits structure.

A Gmm++ standalone version is distributed since release 1.5 of GetFEM. It is however developed inside the GetFEM project even though since release 3.0 it is completely independent of any GetFEM file.

In addition to the linear algebra procedures, it furnishes also the following utilities to GetFEM.

• Fix some eventual compatibility problems in gmm_std.h.
• Error, warning and trace management in gmm_except.h.
• Some extended math definitions in gmm_def.h.

See Gmm++ Library documenation for more details.

## Files¶

All files in src/gmm

## State¶

For the moment, Gmm++ cover the needs of GetFEM concerning the basic linear algebra procedures.

## Perspectives¶

There is potentially several points to be improved in Gmm++ (partial introduction of expression template for some base types of matrix and vectors, think about the way to represent in a more coherent manner sparse sub-vectors and sub-matrices, introduction of C++ concepts, etc.). However, since Gmm++ globally cover the needs of GetFEM and since there exists some other project like Glas to build a reference C++ library for linear algebra, a global change seem to be unnecessary. This part is considered to be stabilized.

The current vocation of Gmm++ is to continue to collect generic algorithms and interfaces to some other packages (DIFFPACK for instance) in order to cover new needs of the whole project. The library is now frequently used as a separate package and has also the vocation to collect the contribution of any person who propose some improvements, new algorithms or new interfaces.