[Trilinos-Users] Amesos UMFPACK

Matt G mgoodman at email.arizona.edu
Fri Apr 16 17:28:40 MDT 2010


Optionally you can compile UMFPACK with the the -DP64 flag.  Its in the
UMFPACK docs somewhere, but I mention it
here<http://craneium.net/index.php?option=com_content&view=article&id=78>.
Things get slower and these sorts of problems memory requirements grow with
DOF^2 or so, so it wont buy you as much as it seems.
--Matthew Goodman

=====================
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On Fri, Apr 16, 2010 at 1:25 PM, Heroux, Mike <MHeroux at csbsju.edu> wrote:

>  Dave,
>
>
>
> The restriction you see on problem size is due to the underlying size
> restriction imposed by the Epetra data classes that are used with Amesos.
> These classes use int as the data type, restricting problem sizes to 2^31.
>
>
>
> A new effort is underway to develop the same capabilities using Tpetra.
> Tpetra uses a template parameter to specify the integer size, and so can use
> any legitimate ordinal type that compiles correctly as the template
> parameter, including 64 bit ints (and 32, 16 bits, or even 8-bit chars).
> Tpetra supports generic scalar types in a similar way, e.g., float, double
> complex<>.
>
>
>
> Using Tpetra, we can support any of  the variety of third-party sparse
> direct solvers for all integer and scalar types.  In addition, we are
> working on a templated version of KLU (the native default solver in Amesos)
> that will allow us to support direct solution methods with any legitimate
> ordinal and scalar types, including important cases such as doubledouble and
> quaddouble (where the mantissa is two and four times as wide as double,
> resp).
>
>
>
> We plan to have a working core of these capabilities done for the Fall 2010
> release of Trilinos.
>
>
>
> Best regards,
>
>
>
> Mike
>
>
>
> *From:* trilinos-users-bounces at software.sandia.gov [mailto:
> trilinos-users-bounces at software.sandia.gov] *On Behalf Of *Dave Makhija
> *Sent:* Friday, April 16, 2010 2:25 PM
> *To:* trilinos-users at software.sandia.gov
> *Subject:* [Trilinos-Users] Amesos UMFPACK
>
>
>
> 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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>
>
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