# Prerequisites
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Prerequisites

The following base libraries are needed:

BLAS
  [11,12,17] Many vendors provide optimized versions of BLAS; if no vendor version is available for a given platform, the ATLAS software (`math-atlas.sourceforge.net`) may be employed. The reference BLAS from Netlib (`www.netlib.org/blas`) are meant to define the standard behaviour of the BLAS interface, so they are not optimized for any particular plaftorm, and should only be used as a last resort. Note that BLAS computations form a relatively small part of the MLD2P4/PSBLAS computations; they are however critical when using preconditioners based on MUMPS, UMFPACK or SuperLU third party libraries. Note that UMFPACK requires a full LAPACK library; our experience is that configuring ATLAS for building full LAPACK does not work in the correct way. Our advice is first to download the LAPACK tarfile from `www.netlib.org/lapack` and install it independently of ATLAS. In this case, you need to modify the OPTS and NOOPT definitions for including -fPIC compilation option in the make.inc file of the LAPACK library.
MPI
  [16,22] A version of MPI is available on most high-performance computing systems.
PSBLAS
  [13,15] Parallel Sparse BLAS (PSBLAS) is available from `github.com/sfilippone/psblas3`; version 3.5.0 (or later) is required. Indeed, all the prerequisites listed so far are also prerequisites of PSBLAS.

Please note that the four previous libraries must have Fortran interfaces compatible with MLD2P4; usually this means that they should all be built with the same compiler as MLD2P4.

Next: Optional third party libraries Up: Configuring and Building MLD2P4 Previous: Configuring and Building MLD2P4 Contents