[petsc-users] PetscMalloc with Fortran

[Peter Brune]

You should be using an array of type ISColoringValue. ISColoringValue is by
default a short, not an int, so you're getting nonsense entries.  We should
either maintain or remove ex5s if it does something like this.

- Peter


On Thu, May 15, 2014 at 11:56 AM, Jonas Mairhofer <
mairhofer at itt.uni-stuttgart.de> wrote:

>
> If 'colors' can be a dynamically allocated array then I dont know where
> the mistake is in this code:
>
>
>
>
>
>        ISColoring iscoloring
>        Integer, allocatable :: colors(:)
>        PetscInt maxc
>
>       ...
>
>
>       !calculate max. number of colors
>       maxc = 2*irc+1 !irc is the number of ghost nodes needed to
> calculate the function I want to solve
>
>      allocate(colors(user%xm))  !where user%xm is the number of locally
> owned nodes of a global array
>
>      !Set colors
>      DO i=1,user%xm
>           colors(i) = mod(i,maxc)
>      END DO
>
>     call
> ISColoringCreate(PETSC_COMM_WORLD,maxc,user%xm,colors,iscoloring,ierr)
>
>     ...
>
>     deallocate(colors)
>     call ISColoringDestroy(iscoloring,ierr)
>
>
>
>
> On execution I get the following error message (running the DO Loop from
> 0 to user%xm-1 does not change anything):
>
>
> [0]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> [0]PETSC ERROR: Arguments are incompatible!
> [0]PETSC ERROR: Number of colors passed in 291 is less then the actual
> number of colors in array 61665!
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: Petsc Release Version 3.4.4, Mar, 13, 2014
> [0]PETSC ERROR: See docs/changes/index.html for recent updates.
> [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
> [0]PETSC ERROR: See docs/index.html for manual pages.
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: ./DFT on a arch-linux2-c-debug named
> aries.itt.uni-stuttgart.de by mhofer Thu May 15 18:01:41 2014
> [0]PETSC ERROR: Libraries linked from
> /usr/ITT/mhofer/Documents/Diss/NumericalMethods/
> Libraries/Petsc/petsc-3.4.4/arch-linux2-c-debug/lib
> [0]PETSC ERROR: Configure run at Wed Mar 19 11:00:35 2014
> [0]PETSC ERROR: Configure options --with-cc=gcc --with-fc=gfortran
> --download-f-blas-lapack --download-mpich
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: ISColoringCreate() line 276 in
> /usr/ITT/mhofer/Documents/Diss/NumericalMethods/
> Libraries/Petsc/petsc-3.4.4/src/vec/is/is/utils/iscoloring.c
>
>
>
>
>
> But when I print out colors, it only has entries from 0 to 218, so no
> entry is larger then 291 as stated in the error message.
>
>
>
>
>
>
>
>
>
>
> Am 15.05.2014 16:45, schrieb Jed Brown:
>
>  Jonas Mairhofer <mairhofer at itt.uni-stuttgart.de> writes:
>>
>>  Hi, I'm trying to set the coloring of a matrix using ISColoringCreate.
>>> Therefore I need an array 'colors' which in C can be creates as (from
>>> example ex5s.c)
>>>
>>> int *colors
>>> PetscMalloc(...,&colors)
>>>
>> There is no PetscMalloc in Fortran, due to language "deficiencies".
>>
>>  colors(i) = ....
>>>
>>> ISColoringCreate(...)
>>>
>>> How do I have to define the array colors in Fortran?
>>>
>>> I tried:
>>>
>>> Integer, allocatable :: colors(:)    and    allocate() instead of
>>> PetscMalloc
>>>
>>> and
>>>
>>> Integer, pointer :: colors
>>>
>>> but neither worked.
>>>
>> The ISColoringCreate Fortran binding copies from the array you pass into
>> one allocated using PetscMalloc.  You should pass a normal Fortran array
>> (statically or dynamically allocated).
>>
>
>
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