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Specialised metis_nodend libraries for 32- and 64-bit HSL usage
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A number of HSL and other sparse-matrix-factorization packages
rely optionally on the open-source graph reordering package MeTiS,
and specifically to its NodeND procedure. Traditionally, access to
MeTiS 4 has been required, but since MeTiS  4 has long been superseded
by the improved MeTiS 5, this has become increasingly inconvenient,
particularly as the MeTiS 4 binaries have to be obtained and compiled
from source.

Of late, an ISO-C wrapper has been provided to enable HSL to call
the MeTiS 5 NodeND procedure. Many Linux distributions provide 
shared 32-bit MeTiS libraries. Thus all appeared to be well.

However, two issues have arisen. The first is that in some cases
supplying null arguments via the (void *)0 syntax that worked
well with MeTiS 5.1, seem not to work reliably with Metis 5.2 (and
vice versa), for which NULL seemingly has to be used instead - most
MeTiS binary distributions are based on 5.1, while 5.2 has extra
enhancements and fixes. Presumably this could be fixed by a 
sufficiently proficient C programmer.

The second - more serious - issue is that many binary distributions 
only support 32-bit integers, while the MeTiS source itself is perfectly 
capable of producing both 32- and 64-bit variants. As we move to support
both 32- and 64-bit calling libraries, we will rely increasingly on the 
same for MeTiS.

Thus, for the foreseeable future, we have decided instead to provide
a cut-down version of the source codes that only builds the NodeND
components, along with a simple Makefile that will produce separate
32- and 64-bit static libraries. This will be distributed as part of 
the upcoming sparseHSL project, but in the interim is available with 
the HSL subset library for users of IPOPT, GALAHAD and other 
optimization packages under MeTiS's open-source licence.

We are extremely grateful to George Karypis, Vipin Kumar and their
collaborators for developing and maintaining this wonderful software.

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Basic install on a Linux system:
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To build both 32- and 64-bit integer static libraries:

 make

To build just the 32-bit-integer library:

 make build_32

To build just the 64-bit-integer library:

 make build_64

To run a simple sanity test of both 32- and 64-bit-integer builds:

 make test

with either

 make test_32

or

 make test_64

as appropriate for the separate tests.

To start again:

  make cleanall

Adjust the compiler by specifying CC= (default gcc) and compiler flags
with CFLAGS= (default is -O3 -pipe -I ./include).

This install will happen by default for those building the HSL subset
from its source.

.........................

Nick Gould, STFC-RAL
for the sparseHSL project
2024-03-22