[mpich-discuss] URGENT.. Passing Array..

[Dave Goodell]

I haven't studied your sample code, but you probably want to create  
two datatypes in your program.  One to describe a column in your image  
and one to describe a row in the image.  MPI_Type_vector is probably  
the most straightforward way to create these types.  The MPI Standard  
[1] (section 4.1.2) provides descriptions of how to use this routine,  
as do many of the books out there such as "Using MPI" [2].

You can then send and receive your rows and columns using these  
derived datatypes.

-Dave

[1] http://www.mpi-forum.org/docs/mpi-2.2/mpi22-report.pdf
[2] http://www.amazon.com/Using-MPI-Programming-Engineering-Computation/dp/0262571323

On Dec 3, 2009, at 12:51 AM, Anuj Patel wrote:

> Hi thanks for reply.
>
> Actually i am trying to paralleling simple HAAR WAVELET.
>
> In that i need to take summation and subtraction of  two row/column  
> out of an very large array(which represents an image) and is in N*N  
> form with very large dimensions.
>
> so what i want to do is pass two row/column to each worker process.
> so in that part i am confused how to do that.
>
> because i studied matrix multiplication but it just passes one row  
> and a complete array to each worker.
>
> i hope i mad it bit clear. and i am attaching serial algo here.
>
> Thanks.
>
> Anuj Patel
>
>
> On Wed, Dec 2, 2009 at 8:50 PM, Dave Goodell <goodell at mcs.anl.gov>  
> wrote:
> On Dec 2, 2009, at 2:07 AM, Anuj Patel wrote:
>
> can anyone tell me how to pass two row and column at a time.?
>
> Can you elaborate a little bit?  Are you trying to pass two rows and  
> two columns of an array as an argument to a function?  Is it in C or  
> Fortran?
>
> Or do you mean how to send an MPI message containing the data from  
> two rows and two columns of an array?
>
> -Dave
>
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