[petsc-users] Calling single-precision MUMPS from PETSC

[Evan Um]

Dear Hong,

Thanks for your reply. In the modified mumps.c, I replaced zmumps_c.h with
cmumps_c.h because I want to use a single precision complex mumps in my
double-precision PETSC application.
In my PETSC application (double precision real and complex versions), I
want to always call a single-precision MUMPS. My understanding is that
mumps.c is designed so that a single precision PETSC application should use
a single-precision MUMPS; a double-precision PETSC should use a
double-precision MUMPS.
I am looking for a way for my double-precision PETSC application to use a
single precision MUMPS. Is it possible for a user to slightly modify
mumps.c and use a single-precision MUMPS in double-precision PETSC? Do I
have to make extra changes beyond the definition parts in mumps.c?
In advance, thanks for your kind help.

Best,
Evan



On Sun, Jun 7, 2015 at 9:55 AM, Hong <hzhang at mcs.anl.gov> wrote:

> Evan,
> The data types are defined as
> s: single real
> d: double real
> c: single complex
> z: double complex
>
> see
> https://books.google.com/books?id=4E9PY7NT8a0C&pg=PA22&lpg=PA22&dq=SDCZ+data+type&source=bl&ots=rd44BVkxjc&sig=KGxae_a5N54KD-AbO9CBnOE53CA&hl=en&sa=X&ei=IXJ0VeG7CNX-yQSujoOQCg&ved=0CDEQ6AEwAw#v=onepage&q=SDCZ%20data%20type&f=false_
>
> Our mumps interface uses these definitions.
>
> I do not understand why you suggest replacing z to c for double complex:
>
> #if defined(PETSC_USE_COMPLEX)
> #if defined(PETSC_USE_REAL_SINGLE)
> #include <cmumps_c.h>
> #else
> //#include <zmumps_c.h> // old
> #include <cmumps_c.h>   // new
> #endif
>
> and replacing d to s for double real:
> #if defined(PETSC_USE_REAL_SINGLE)
> #include <smumps_c.h>
> #else
> //#include <dmumps_c.h>  // old
> #include <smumps_c.h> // new
> #endif
>
> Hong
>
>
>
>
> On Fri, Jun 5, 2015 at 6:26 PM, Evan Um <evanum at gmail.com> wrote:
>
>> Dear Barry and PETSC users,
>>
>> I am revisiting a problem about how to call a single precision MUMPS from
>> double precision real/complex PETSC. After taking a look at mumps.c, I feel
>> that the following changes (attached) can make it possible to always call a
>> single precision MUMPS from PETSC. The change is basically to replace
>> double precision MUMPS and their associated types with corresponding single
>> ones. If someone already has some experience about this work, could you
>> comment on the change? In advance, I appreciate your help.
>>
>> Best,
>> Evan
>>
>> On Wed, Oct 22, 2014 at 1:36 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>
>>>
>>>    There is no support for this. You can only call single precision
>>> MUMPS from single precision PETSc and double precision MUMPS from double
>>> precision PETSc.
>>>
>>>     You could try to hack the interface that calls MUMPS from PETSc to
>>> use the single precision version but we don’t support that.
>>> src/mat/impls/aij/mpi/mumps/mumps.c
>>>
>>>   Barry
>>>
>>> > On Oct 22, 2014, at 3:29 PM, Evan Um <evanum at gmail.com> wrote:
>>> >
>>> > Dear PETSC users,
>>> >
>>> > When MUMPS is used inside PETSC, The default MUMPS driver seems to be
>>> double-precision MUMPS (i.e. DMUMPS). To reduce memory costs, I want to
>>> test a single-precision MUMPS (SMUMPS) from PETSC. Does anyone know how to
>>> switch from double to single-precision MUMPS inside PETSC? In advance,
>>> thanks for your comments.
>>> >
>>> > Regards,
>>> > Evan
>>>
>>>
>>
>
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