The user functions of ELPA are now documented with doxygen tags.
At the moment the interface of ELPA 2015.11.001 is decribed.

The documentation has step by step to be implemented for all functions
and test programms.

This variables, do not have to be global, they can be parsed along
internally in ELPA. Removing them makes debugging more easy and
the public interface more lean

The API versioning number was not updated correctly at the release.
This lead to a wrong soname.

This is fixed now

Due to the efforts of Intel, ELPA features now build-in
support of AVX2 and FMA for the latest Intel processors

The examples, how to invoke ELPA from a c program have been updated.
There are now examples for ELPA1 and ELPA2 both real and complex case.
The test cases are still with less functionality than their Fortran
counter parts, they are just ment as a "proof-of-concept".

Inge Gutheil from FZ Juelich pointed out, that the
configure test for BGQ failed due to typos.
These are corrected now

An "dangling" fi has been removed

Remove variables which are not needed (anymore)

The macros which define the functionality to test
for
 - a specific real/complex kernel (not all available kernels)

are now defined in files in the m4 directory

There was an inconsistency when the OpenMP flag was different for the
Fortran and C compiler (e.g. -openmp for ifort and -fopenmp for gcc).

This led to strange errors when linking the example program with the C
main() routine when using Intel Fortran, Intel MPI, and GCC together, a
typical error message was

  /usr/bin/ld: MPIR_Thread: TLS definition in [...]/intel64/lib/libmpi_dbg_mt.so section .tbss mismatches non-TLS definition in [...]/intel64/lib/libmpi_dbg.so section .bss
  [...]/intel64/lib/libmpi_dbg_mt.so: could not read symbols: Bad value

The reason seems to be that the various MPI wrapper shell scripts
(mpicc, mpiifort) need the correct OpenMP option to select the
thread-safe Intel MPI debug library. Previously, always OPENMP_FCFLAGS
was appended to LDFLAGS, which did not trigger this when linking a C
main program with mpicc.

Just adding -maxv works on many systems which have compiler that can
produce AVX code but do not necessarily have processors with AVX
support.

The flag -mavx was not removed from C/CXXFLAGS again if AVX is unusable

Andreas Marek authored Mar 18, 2015 and Lorenz Huedepohl committed Mar 18, 2015

- provide C interface for ELPA Library

- correct an error in the test case for QR-decomposition

Some compilers detected the static out-of-bounds condition present in
the test code and refused to compile it.

C interfaces are now available and definied in the header
elpa.h

Error in configure test program fixed

As obvious from the previous commits, this release of ELPA
introduces a (optional) QR-decomposition for real valued
matrices. This option can be used at run-time by either setting
an environment variable, or by calling the ELPA-2 solver for
real matrices with an additional flag.

Thus the ABI changed, w.r.t. previous versions.

Furthermore, the build process of ELPA has been made more
consistent. All optimization flags (especially O1, O2 etc.)
have to be set at build time by the user via the CFLAGS, FCFLAGS,
and CXXFLAGS variables. The configure script does not set
automatically the "O-Flags" anymore.

Some users where "clever" enough to supply a library in LDFLAGS/LIBS
thath contained omp_get_num_threads, therefore tricking configure into
thinking that we do not need any flags to enable OpenMP.

Now the Fortran test only works if "use omp_lib" and "!$" OpenMP
conditional compilation work.

Also, if no valid OpenMP flag could be detected configure silently
continued. I changed this to an explicit error.

The qr decomposition is now available as a runtime choice.
Some testing has still to be done

At build time it can be specified that the ELPA test
programs give more detailed timing information, which
is usefull for performace measurements

If specified in the configure step, the test programs
redirect their stdout and stderr output of each MPI
task in a seperate file, which will be stored in a
subdirectory "mpi_stdout".

This will only be done if the environment variable
"REDIRECT_ELPA_TEST_OUTPUT" is set to "true"

These programs have not been updated correctly

It was decided that the version number shall be all of 2014.06.001, that
is including the release version.

Sadly, pkg-config is not too flexible with different versions of
libraries, therefore the pkg-config file will have the full version
number including the release. This might be a bit cumbersome for
dependent projects.

It was decided that the library file shall be called

  libelpa.so.*

without an explicit version string. Version information will be encoded
by using the -version-info parameter of libtool, resulting in an actual
filename as defined by your flavor of Unix.

The file LIBRARY_INTERFACE documents the changes, the current interface
has number 1 and is binary incompatible with the previous version 0.

_mt implies thread-safety, which is not what the OpenMP version does.

Additionally, only install a subset of the test-programs

libtool was too smart and mixed Intel and GNU OpenMP libraries

The Intel MPI g++ compiler wrapper otherwise links with the
non-threadsafe mpi libary instead of mpi_mt, leading to link errors.