[Coin-ipopt] Re: [Coin-discuss] IPOPT: build and linking questions

[John Pye]

Hi Damien,

damien at khubla.com wrote:
> MUMPS can be a long compile depending on how you set it up.  It comes with
> 4 versions by default:  single and double precision real, and single and
> double precision complex.  If you build all 4 it definitely takes a while.
>  On *Nix/*Nux, you can change the MUMPS top-level makefile to just build
> the double-precision real version which speeds things up a bit.
>   

Packaging of MUMPS on Linux could be set up with four different packages
for each of these cases, so long as each .so can have a different name.
I take it that IPOPT only ever needs to the double precision version?
There will need to be a place where the *name* of the MUMPS shared
library can be specified to the configure options.

> Dynamically loading a MUMPS .so or dll is feasible and worth considering. 
> BUT:  Remember that IPOPT is used on Windows as well (MUMPS was first put
> into IPOPT on a Windows build before it was submitted to COIN) and the
> syntax for loading dynamic libraries on *Nix/*Nux and Windows is
> different.  There's only one major entry point for calling MUMPS, and
> making a dynamically-loadable library on both platforms is doable.  I'll
> have a look at the code in the next little while and try a few things out.
>   

If it is of any help, here is a file that is fairly well tested for
dlopening on both Windows and Linux, as well as having been used on
other platforms in the past as well:

http://ascendcode.cheme.cmu.edu/viewvc.cgi/code/branches/extfn/base/generic/utilities/ascDynaLoad.c?revision=1433&view=markup

It is worth noting that when you make use of LoadLibrary or dlopen you
also need to think about configuration of appropriate environment
variables eg LD_LIBRARY_PATH (*n*x) or PATH (Windows). In the above,
take a look at Asc_DynamicLoad and SearchArchiveLibraryPath.

If a MUMPS shared library were possible, it could be packaged as a
separate RPM/DEB available to Linux users from their standard
repositories. This would certainly make the job of getting started with
IPOPT that little bit easier for those people.

Cheers
JP