[Trilinos-Users] Amesos UMFPACK

Dave Makhija makhijad at colorado.edu
Fri Apr 16 13:25:08 MDT 2010

I'm having trouble solving large linear systems using UMFPACK in Trilinos
when the same system can be solved with Matlab's UMFPACK with no problem.
The error returned is "Out of Memory", but this happens when 20% of our
memory resources are being used. Here is the problem:

UMFPACK 5.4 documentation lists their naming convention for user callable
routines as,

"1. umfpack di *: real double precision, int integers.
2. umfpack dl *: real double precision, UF long integers.
3. umfpack zi *: complex double precision, int integers.
4. umfpack zl *: complex double precision, UF long integers."

The UMFPACK documentation also talks about compiling options for 32 bit or
64 bit UMFPACK and says,
"In the LP64 [64 bit] mode, the umfpack_dl_* and umfpack_zl_* routines can
solve huge problems (not limited to 2GB), limited of course by the amount of
available memory."

However, in trilinos-10.2.0-Source/packages/amesos/src/Amesos_Umfpack.cpp it
clearly uses only the umfpack_di* (32 bit, 2GB max) routines.

So the entire interface to the UMFPACK solver is hard coded to only do
relatively small problems (2GB max)? Are there any releases or workarounds
that can use the 64 bit UMFPACK routines (umfpack_dl_*)? I'm not sure how
much work it would be to convert it myself, but I'm guessing if it's not
included in Amesos already that it would be relatively hard to change.
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