===========================================
MUMPS 5.8.1 INSTALLATION
===========================================

Pre-requisites
--------------

If you only want to use the sequential version, you need:
-> an optimized sequential or multithreaded BLAS library
-> the LAPACK library

If you want to use MUMPS on a multicore machine, you need:
-> a multithreaded BLAS library
-> the LAPACK library
-> additional gains can be expected compiling/linking with OpenMP
   (see userguide, sections "Combining MPI and multithreaded parallelism"
    and "Enabling the BLR functionality at installation")

If you want to use the parallel (distributed memory MPI based) version, 
you need:
-> MPI
-> BLAS library 
-> BLACS library
-> LAPACK and ScaLAPACK libraries

For performance (time and memory issues) we very strongly recommend to install:
-> SCOTCH and/or METIS for the sequential and parallel versions
-> PT-SCOTCH and/or ParMetis to parallelize the analysis phase (parallel version
only: ParMetis and PT-SCOTCH must be disabled for the sequential version as
this would otherwise lead to undefined MPI symbols at the link phase)


Installation
------------

The following steps can be applied.

% tar zxvf MUMPS_5.8.1.tar.gz
% cd MUMPS_5.8.1

You then need to build a file called Makefile.inc corresponding
to your architecture. A few examples are available in the
directory Make.inc :

 Makefile.debian.SEQ       : default for debian systems with standard packages, sequential version
 Makefile.debian.PAR       : default for debian systems with standard packages, parallel version
 Makefile.FREEBSD10.SEQ    : default Makefile.inc for a FreeBSD system, sequential version.
 Makefile.FREEBSD10.PAR    : default Makefile.inc for a FreeBSD system, parallel version.
 Makefile.G95.SEQ          : default Makefile.inc for the G95 compiler, sequential version.
 Makefile.G95.PAR          : default Makefile.inc for the G95 compiler, parallel version.
 Makefile.INTEL.SEQ        : default for PC with the Intel suite (compilers and MKL), sequential.
 Makefile.INTEL.PAR        : default for PC with the Intel suite (compilers, MPI and MKL), parallel.
 Makefile.NEC.SEQ          : default Makefile.inc for a NEC, sequential version.
 Makefile.NEC.PAR          : default Makefile.inc for a NEC, parallel version.
 Makefile.SGI.SEQ          : default Makefile.inc for an Origin, sequential version.
 Makefile.SGI.PAR          : default Makefile.inc for an Origin, parallel version.
 Makefile.SUN.SEQ          : default Makefile.inc for a SUN, sequential version.
 Makefile.SUN.PAR          : default Makefile.inc for a SUN, parallel version.
 Makefile.SP64.SEQ         : default for SP (64 bits), sequential version.
 Makefile.SP64.PAR         : default for SP (64 bits), parallel version.
 Makefile.WIN.MS-Intel.SEQ : default for Windows with Intel compiler, sequential, with GNU make.
 Makefile.WIN.MS-G95.SEQ   : default for Windows with g95 compiler, sequential, with GNU make.

For example, a parallel version of MUMPS on a debian or ubuntu system and
standard packages copy Make.inc/Makefile.debian.PAR into Makefile.inc:

% cp Make.inc/Makefile.debian.PAR ./Makefile.inc

However, in most cases, Makefile.inc should be adapted to fit with
your architecture, libraries and compilers (see comments in the
Makefile.inc.generic or Makefile.inc.generic.SEQ for details).  The
variables LIBBLAS (BLAS library), SCALAP (ScaLAPACK and LAPACK libraries),
INCPAR (include files for MPI), LIBPAR (library files for MPI) are concerned.
We also strongly recommend to install METIS and/or SCOTCH, see the
ordering section of Makefile.inc.
Makefile.inc also contains a line "PLAT=" which defines an empty $(PLAT)
Makefile variable. You can use it to add a default suffix to the generated
libraries.

By default, only the double precision version of MUMPS will be
installed, with static MUMPS libraries. The command:
% make <ARITH>
will build the version for a specific arithmetic, where <ARITH> is
one of 's', 'd','c','z' (for single precision real, double precision real,
complex, and double complex). The command:
% make all
will compile versions of MUMPS for all 4 arithmetics.


After issuing the command:
% make all
, ./lib will contain the mumps libraries libxmumps.a (with x = 'd', 'c',
's' or 'z') and libmumps_common.a. Both must be included at link time in
an external program.

A simple Fortran test driver in ./examples (see ./examples/README) will
also be compiled as well as an example of using MUMPS from a C main
program.


Dynamic libraries:
-----------------

Instead of static libraries, you can build dynamic libraries:
make sshared
make dshared
make cshared
make zshared
make allshared

Make sure to do a 'make clean' if you previously installed static libraries,
since dynamic libraries require the -fPIC option during compilation (if
needed, the definition FPIC_OPT=-fPIC can be adapted in the Makefile.inc)

The dynamic libraries (e.g. libmumps.so, libdmumps.so, etc.) are
installed in the directory MUMPS_5.8.1/lib/
so that including the directory MUMPS_5.8.1/lib in your
LD_LIBRARY_PATH environment variable will allow them to be successively
loaded at runtime. Alternatively, you can uncomment and adapt the line
#RPATH_OPT= -Wl,-rpath /path/to/MUMPS_5.8.1/lib
in the Makefile.inc

Although we do not currently support an official SONAME, note that, given a
version x.y.z of MUMPS, it is binary/ABI compatible with x.y.z' versions,
but not with x.y'.z'' versions.


Preprocessing constants
-----------------------

This section describes some preprocessing flags that can be added in the
OPTF and OPTC variables of Makefile.inc.


-DDETERMINISTIC_PARALLEL_GRAPH:
When using several MPI processes, the order of the edges of the graphs
constructed by MUMPS in parallel may vary between successive execuions.
Ordering packages (e.g., SCOTCH, PT-SCOTCH, METIS, parMETIS) are
sensitive to this order, possibly leading to different flops and
memory estimates between executions.

When compiling MUMPS with -DDETERMINISTIC_PARALLEL_GRAPH, the order of
the edges of the graph passed to ordering packages will be identical
for each run.

-DMAIN_COMP:
Note that some Fortran runtime libraries define the "main" symbol.
This can cause problems when using MUMPS from C if Fortran is used
for the link phase. One approach is to use a specific flag (such
as -nofor_main for Intel ifort compiler). Another approach is to
use the C linker (gcc, etc...) and add manually the Fortran runtime
libraries (that should not define the symbol "main"). Finally, if
the previous approaches do not work, compile the C example with
"-DMAIN_COMP". This might not work well with some MPI implementations
(see options in Makefiles and the FAQ page at http://mumps-solver.org). 

-DAdd_ , -DAdd__ and -DUPPER:
These options are used for defining the calling
convention from C to Fortran or Fortran to C. 

Some other preprocessing options correspond to default
architectures and are defined in specific Makefiles.

-DPRINT_BACKTRACE_ON_ABORT:
Print backtrace (BACKTRACE with GFORTRAN and TRACEBACKQQ with INTEL_COMPILER)
in case of call to MUMPS_ABORT()

-DMUMPS_USE_BLAS2:
Some BLAS vendor libraries have more efficient BLAS3 than BLAS2 routines,
even when one of the dimensions is set to 1. For this reason MUMPS
typically avoids BLAS2 calls and replaces them by BLAS3 calls with one
dimension set to 1 (e.g. avoid dgemv and use dgemm instead). The flag
-DMUMPS_USE_BLAS2 keeps the BLAS2 calls instead of replacing them by
BLAS3 calls with one of the dimensions set to 1.

-DBLR_NOOPENMP:
When this flag is used, the BLR feature will use multithreaded BLAS and
not call BLAS within OpenMP regions. To be used only if there is a
problem of compatibility between the BLAS library and OpenMP, or
for debugging purposes.

-DNOSCALAPACK
When this flag is used, MUMPS does not need to be linked with the
BLACS and ScaLAPACK libraries. This is not recommended because
performance can be decreased. ICNTL(13) will be ignored if it
is set to 0.

-DAVOID_MPI_IN_PLACE:
MUMPS uses MPI_IN_PLACE in some collective MPI operations. In case of
MPI environments where MPI_IN_PLACE is failing, it is possible to
avoid the use of MPI_IN_PLACE at the cost of more temporary memory
allocation and possibly less efficient code.

-DMUMPS_SCOTCHIMPORTOMPTHREADS:
MUMPS provides OpenMP threads to multithreaded SCOTCH/PT-SCOTCH,
instead of letting SCOTCH creating new threads. This feature can,
in some cases, resolve thread affinity issues impacting performance
negatively. Note that, when Scotch 7.0.4 is compiled with cmake, the
symbol scotchfcontextrandomclone is missing from the Scotch library.
To solve this issue, you may either compile Scotch 7.0.4 with make,
or add "library_context_f.c" after "library_context.c" in the file
"scotch-v7.0.4/src/libscotch/CMakeLists.txt".

-DNO_SAVE_RESTORE:
Disables the save restore feature.  RINFO(7), RINFO(8), RINFOG(17),
RINFOG(18) will no longer be computed, and a call to MUMPS with
JOB=7 or JOB=8 will lead to an error.


Sequential version
------------------

You can use the parallel MPI version of MUMPS on a single
processor. If you only plan to use MUMPS on a uniprocessor
machine, and do not want to install parallel libraries
such as MPI, ScaLAPACK, etc... then it might be more convenient
to use one of the Makefile.<ARCH>.SEQ to build a sequential
version of MUMPS instead of a parallel one.

For that, a dummy MPI library (available in ./libseq) defining
all symbols related to parallel libraries is used at the link
phase.

Note that you should use 'make clean' before building the
MUMPS sequential library if you had previously built a parallel
version. And vice versa.


Compiling and linking your program with MUMPS
---------------------------------------------

Basically, ./lib/lib[sdcz]mumps.a and ./lib/libmumps_common.a constitute the
MUMPS library and ./include/*.h are the include files. Also, some BLAS, LAPACK,
ScaLAPACK, BLACS, and MPI are needed. (Except for the sequential version
where ./libseq/libmpiseq.a is used.) Please refer to the Makefile
available in the directory ./examples for an example of how to link your
program with MUMPS. We advise to use the same compiler alignment options
for compiling your program as were used for compiling MUMPS. Otherwise
some derived datatypes may not match.

Using MUMPS from an existing project
------------------------------------

If you want to use MUMPS from outside the MUMPS installation directory,
please make sure the ./lib/ and ./include/ directories can be accessed,
and start from the Makefile.inc used at installation and the Makefile
available in ./examples as models.


Interface with the Metis and ParMetis orderings
-----------------------------------------------

Since the release of MUMPS 4.10.0, the Metis API has changed.
MUMPS 5.0 and later versions assume that Metis 5.1.0 or 
ParMetis 4.0.3 or later are installed, and that the newer
versions of Metis/ParMetis are backward compatible with Metis
5.1.0/ParMetis 4.0.3.

It is however still possible to continue using Metis
versions 4.0.3 or lower by forcing the compilation flag -Dmetis4
in your Makefile.inc, and to continue using ParMetis versions
3.2.0 or lower by forcing the compilation flag -Dparmetis3.

Note that Metis 5.0.3 and ParMetis 4.0.1/4.0.2 have
never been supported in MUMPS.


32-bit versus 64-bit Fortran integers
-------------------------------------

MUMPS uses a mix of 32-bit and 64-bit integers depending on the
possible sizes of the integers that must be manipulated.

Most integers at the MUMPS interface level are 32-bit integers: only
NNZ and NNZ_loc are 64-bit integers, as the number of non-zeros in a
matrix can exceed the 32-bit integer limit on large problems.
Internally, MUMPS uses a mix of 32-bit and 64-bit integers. 64-bit
integers are mainly used for data proportional to NNZ or NNZ_loc
or to address large arrays. However, external libraries like BLAS,
MPI, (Sca)LAPACK, can remain 32-bit.

For each ordering, the user should decide at installation time if
the ordering manipulates 32-bit or 64-bit indices. 64-bit integers
are recommended if the number of nonzeros in the matrix becomes
significant as compared to 2^31-1

- for PORD: by default, PORD is installed in a way compatible with
standard integers (Fortran INTEGER). Installation of MUMPS with
-DPORD_INTSIZE64 (i.e.  adding the -DPORD_INTSIZE64 option to the 
OPTC variable from your Makefile.inc) will install PORD with 
64-bit integers and MUMPS will also call PORD with 64-bit integers.
Warning: if you activate or deactivate -DPORD_INTSIZE64 between two
installations, the previously installed pord library should be
cleaned before recompilation. This can be done with "make clean".

- for METIS/parMETIS: in the file metis.h (assuming here a version of
metis >= 5), it is possible to modify the line
"#define IDXTYPEWIDTH 32"
by 
"#define IDXTYPEWIDTH 64"
in order to use 64-bit integers for indices (see comments in metis.h
for more information). MUMPS will then check the value of IDXTYPE in
metis.h in order to call METIS with integer parameters of the
correct datatype.

- for scotch/pt-SCOTCH: in scotch.h, you can compile SCOTCH either
with -DINTSIZE32 (default) or with -DINTSIZE64, in order to process
large graphs. MUMPS will then check the size of a SCOTCH integer in
scotch.h in order to call SCOTCH with integer parameters of the
correct datatype

Finally, it is possible to force all integers to be 64-bit at installation.
This can be useful, if, for example, MUMPS is called from an environment
where all integers are 64-bit. This approach relies:
i) on a Fortran compiler flag (e.g., -i8, -fdefault-integer-8, or something
else, depending on your compiler) that should be added in the OPTF variable
from the Makefile.inc corresponding to your local configuration.
ii) on forcing a 64-bit default integer in C code, by adding the -DINTSIZE64
option to the OPTC variable from your Makefile.inc (remark that this option
will also force an installation of PORD with 64-bit integers, since PORD
installation is based on the same OPTC variable)
iii) on the fact that all external libraries called by MUMPS should use
64-bit integers. In particular, all external orderings must have been compiled
with 64-bit integers as we have not developed 64-bit to 32-bit wrappers.

Furthermore:
- for the MPI-free version, METIS, SCOTCH, BLAS, LAPACK should thus
  also rely on 64-bit integers.

- for the MPI version, one also needs an MPI (and ScaLAPACK) implementation
  where all integers are 64-bit (both MPI_INTEGER and counts).

  Remark that for this latter point, Intel provides an ilp64 version of
  MPI where integers (counts, MPI_INTEGER, ...) are 64-bit. However, in
  the MPI versions we have tested, MPI_2INTEGER which could be expected
  to be 128-bit in that case is only 64-bit, see Intel documentation.
  In order to have MUMPS working correcly with such MPI versions, please
  try adding -DWORKAROUNDINTELILP64MPI2INTEGER to the OPTF variable of
  your Makefile.inc

  Platform MPI also provides an interface for 64-bit default integers,
  for which we had feedback that MUMPS should be compiled with
  -DWORKAROUNDILP64MPICUSTOMREDUCE (but not -DWORKAROUNDINTELILP64MPI2INTEGER)

- The OpenMP runtime library should also rely on 64-bit integers. Adding
  -DWORKAROUNDINTELILP64OPENMPLIMITATION to the OPTF variable from the
  file Makefile.inc will use 32-bit integers during OpenMP calls and
  avoid warnings in an Intel environment.

  When including MUMPS headers files from a  C application,
  one can check at compilation time the preprocessing constants
  MUMPS_INTSIZE32 and MUMPS_INTSIZE64 (see include/mumps_int_def.h generated
  during the build process and include/mumps_c_types.h) in order
  to see how MUMPS_INT was defined. At runtime, one can simply check
  sizeof(MUMPS_INT). If for some reason you are building MUMPS without
  using 'make', you can copy into include/mumps_int_def.h either
  src/mumps_int_def32_h.in (or src/mumps_int_def64_h.in in case of
  a MUMPS installation with 64-bit default integers).


Using BLAS extension GEMMT
--------------------------

If the BLAS library includes the GEMMT level-3 BLAS
extension, we strongly recommend to use it.
-DGEMMT_AVAILABLE should then be added to the OPTF variable of your Makefile.inc. 
This can significantly improve the performance of the factorization of
symmetric matrices.  To be compatible, the GEMMT signature should be the
same as the ones described at

https://www.intel.com/content/www/us/en/docs/onemkl/developer-reference-fortran/2023-0/gemmt.html

https://sxauroratsubasa.sakura.ne.jp/documents/sdk/SDK_NLC/UsersGuide/man/dgemmt.html


Platform and software dependencies
----------------------------------

Versions of MUMPS have been tested on a large range of platforms.
MUMPS is potentially portable to any platform having a C and
Fortran 90 compiler as well as MPI, BLACS, and ScaLAPACK installed.

* WINDOWS
  -------

Although the MUMPS development team is not using Windows, you
may be interested by discussions on this topic in the archives
of MUMPS users, or by links to contributions from users (see the
MUMPS website, and follow "Links").
-DMUMPS_WINLARGEFILES is designed to reduce the number of file
descriptors under Windows and allow for files larger than 2GB.


* FREEBSD AND SOLARIS
  -------------------

Under FreeBSD and Solaris, please check that the spaces are
kept after the definition of commands. For example, use
AR = ar -vr "" 
to force keeping the space after ar -vr
See the example Makefile.FREEBSD10 in the Make.inc/ directory.

Note that the absence of space in the main Makefile
is motivated by portability on Windows environments.

* gfortran versions >= 10
  -----------------------

For MUMPS to compile with gfortran versions greater or equal t 10,
the option '-fallow-argument-mismatch' should be included in OPTF
in your Makefile.inc

* MAC OSX
  -------

Dominique Orban has developed a Homebrew formula for MUMPS.
Please check the "Links" page at http://mumps-solver.org and
http://brew.sh


* LAM
  ---
lam version 6.5.6 or greater is required for the double complex
version of MUMPS to work correctly.

* MPICH
  -----
The double complex version does not work correctly with MPICH2 v 1.0.3,
due to truncated messages when using double complex types.

* CRAY
  ----
At least with old CRAY versions, we recommend to link with the
standard BLACS library from netlib, based on MPI. We observed
problems (deadlock) when using the CRAY BLACS in host-node mode
or when MUMPS is used on a subcommunicator of MPI_COMM_WORLD
of more than 1 processor.
With recent Cray compilers, the flag -DMUMPS_ALLOC_FROM_C should
be used, to avoid some Fortran pointer manipulations not allowed
by the compiler.

