[Users] Going from lapacke.h to mkl_lapacke.h

[Chris Stevens]

Hi Erik,

thanks for the reply.

It sounds like it will be ok, as my output is not crazy, although I will 
double check the arguments of the functions in the mkl header.

Thanks,

Chris


On 03/25/2018 01:57 AM, Erik Schnetter wrote:
> Chris
>
> I don't think the "mkl_" prefix is significant. I would look out for two things:
>
> (1) I would compare the names, types, and order (!) of the arguments
> to the functions you are calling, ensuring that they are what you are
> expect. The Fortran versions of these routines are well standardized,
> but the C versions might have a different convention. I don't expect
> any difference there.
>
> (2) I would check that the size of an int (32 or 64) is what you
> expect. This can usually be chosen at compile time. I know that MKL
> supports both, so you need to choose the right library at link time
> that corresponds to the choice you made at compile time. I don't
> recall how that choice is made at compile time -- it could be the
> include path, the include file name, or a preprocessor flag that you
> set. Of course, this needs to correspond to the actual int size that
> you use in your code. Most likely, your int has 32 bit, which is
> insufficient if you have really large vectors (with more than 2e9
> elements). If you get this wrong, you either get completely
> nonsensical results or a segfault.
>
> -erik
>
>
>
> On Sat, Mar 24, 2018 at 1:47 PM, Chris Stevens <c.stevens at ru.ac.za> wrote:
>> Hi Erik,
>>
>> thanks for your quick reply. I'm not so worried about the error, it actually
>> seems to be an MPI issue, even though MPI worked fine on the smaller
>> cluster. Hopefully it isn't a pain to fix.
>>
>> What I really want to know is the difference between the standard lapacke
>> and intel's mkl one. Is the only difference between the two, if all I used
>> before was functions defined in lapacke.h, to replace this with
>> mkl_lapacke.h? The code seems to run fine with only this change, but I
>> remember seeing somewhere standard lapack function calls but with mkl__
>> appended at the front. I want to know if I should also modify these function
>> calls as well to make proper use of the mkl. The mkl_lapacke.h header file
>> itself doesn't seem very insightful.
>>
>> I can't seem to find much useful documentation on this through google...
>>
>> Cheers,
>>
>> Chris
>>
>>
>> On 03/24/2018 04:50 PM, Erik Schnetter wrote:
>>
>> Chris
>>
>> Can you say what is actually going wrong? We need to see an error message or
>> similar to help out.
>>
>> -erik
>>
>> On Sat, Mar 24, 2018 at 03:38 Chris Stevens <c.stevens at ru.ac.za> wrote:
>>> Hi everyone,
>>>
>>> I have just ported my code from a local cluster to larger one which uses
>>> intel mkl and wanted to clarify the changes I've made are the correct ones
>>> wrt the lapacke library:
>>>
>>> -- In the local cluster, I had the option
>>>
>>> LAPACK_LIBS = lapack lapacke in my .ini file
>>>
>>> and used #include "lapacke.h" in the code.
>>>
>>> -- In the bigger cluster, I now have to use intel mkl, and I have the
>>> following options in my .cfg
>>>
>>> LAPACK_DIR  =
>>> /apps/compilers/intel/parallel_studio_xe_2016/mkl/lib/intel64
>>>
>>> LAPACK_LIBS = -mkl
>>>
>>> which will only compile my code if I replace #include "lapacke.h" with
>>> #include "mkl_lapacke.h".
>>>
>>> Question: Is this the right way to generalise to mkl lapacke?
>>>
>>> Problem: The code runs fine on the local cluster, but breaks (not obvious
>>> where) on the larger one with the above changes. The lapacke functions seem
>>> to work OK at a glance, but seeing as this is the only thing that has
>>> changed this may still be the culprit.
>>>
>>> Question: Do I perhaps need to change the lapacke function calls also? The
>>> mkl_lapacke.h header file doesn't seem to give much insight... I think I
>>> remember seeing somewhere calls replaced something like
>>>
>>> LAPACKE_dgels -> MKL_LAPACKE_dgels
>>>
>>> Thanks!
>>>
>>> Chris
>>>
>>> --
>>> Dr Chris Stevens
>>>
>>> Claude Leon Postdoctoral Fellow
>>>
>>> Department of Mathematics
>>>
>>> Rhodes University
>>>
>>> Room 5
>>>
>>> Ph: +27 46 603 8932
>>>
>>> Web: www.chrisdoesmaths.com
>>>
>>> _______________________________________________
>>> Users mailing list
>>> Users at einsteintoolkit.org
>>> http://lists.einsteintoolkit.org/mailman/listinfo/users
>> --
>> Erik Schnetter <schnetter at cct.lsu.edu>
>> http://www.perimeterinstitute.ca/personal/eschnetter/
>>
>>
>> --
>> Dr Chris Stevens
>>
>> Claude Leon Postdoctoral Fellow
>>
>> Department of Mathematics
>>
>> Rhodes University
>>
>> Room 5
>>
>> Ph: +27 46 603 8932
>>
>> Web: www.chrisdoesmaths.com
>
>

-- 
Dr Chris Stevens

Claude Leon Postdoctoral Fellow

Department of Mathematics

Rhodes University

Room 5

Ph: +27 46 603 8932

Web: www.chrisdoesmaths.com <http://www.chrisdoesmaths.com>

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