DOLFIN User Manual - FEniCS Project

Chapter 3Linear algebra◮ Developer’s note: This chapter is currently being written. . .DOLFIN does not have its own linear algebra routines, but instead uses theexternal package PETSc [11] for linear algebra functionality.PETSc is a suite of data structures and routines for the scalable (parallel)solution of scientific applications modeled by partial differential equations.It employs the MPI standard for all message-passing communication.For convenience DOLFIN provides wrappers for some of the most commonlinear algebra functionality. For more advanced usage, DOLFIN providesdirect access to the PETSc pointers to be used with the standard PETScinterface.3.1 Matrices and vectorsThe matrix class Matrix provides wrappers for initializing a sequential sparsematrix, or a sequential sparse matrix in block compressed row format. Forparallel matrices the PETSc interface has to be used directly.The code for initializing a sequential sparse M × N matrix takes the form:25