Recreating upstream tarball
===========================

atlas*.tar.gz is modified from upstream.

*.pdf are removed from the tarball and the TexDoc directory from the CVS
AtlasBase module is included.


Tuning of the library
=====================

The ATLAS build system, before creating the binaries, first performs a very
long series of timing tests in order to tune the library to the precise CPU on
which it is built.

However, this process sometimes fails because reliable timings cannot be
obtained. In that case, the build log will contain the following near the end:
"VARIATION EXCEEDS TOLERANCE, RERUN WITH HIGHER REPS". The solution is simply
to run the build again [1].

This situation is not convenient for build daemons, because it means that for
every new source package, it is necessary to ask for several give backs before
getting the package compiled on all arches.

In order to overcome this problem, the generic ATLAS package uses pre-computed
timings (called architectural defaults in the ATLAS jargon). These are located
under debian/archdefs/$(DEB_HOST_ARCH_CPU). The name of the tarballs
corresponds to the architecture detected by ATLAS (variable ARCH in
build/Make.inc).

The procedure for creating these architectural defaults on a given platform is
the following:

 debuild -us -uc -B    (will be very long, because timings will be computed)
 cd build/ARCHS
 make ArchNew          (will create an $(ATLAS_ARCH) subdirectory)
 tar caf $(ATLAS_ARCH).tar.bz2 $(ATLAS_ARCH)
 mkdir -p ../../../debian/archdefs/$(DEB_HOST_ARCH_CPU)/
 mv $(ATLAS_ARCH).tar.bz2 ../../../debian/archdefs/$(DEB_HOST_ARCH_CPU)/
 echo debian/archdefs/$(DEB_HOST_ARCH_CPU)/$(ATLAS_ARCH).tar.bz2 >> ../../../debian/source/include-binaries

[1] http://math-atlas.sourceforge.net/errata.html#tol

 -- Sébastien Villemot <sebastien@debian.org>, Tue,  1 Aug 2017 18:03:42 +0200

