[mpich-discuss] about long int number

[Jayesh Krishna]

 Hi,
  I would recommend using MPI datatypes for your problem (eg: Creating a
vector, see MPI_Type_vector(), with say 2 ints, you can send MAX_INT*2
integers).
  Let us know if you need further help.

(PS: The sizes of the various built-in language datatypes, like int,
depends on the data model adopted by the compiler. Using say the Visual
studio compiler, cl.exe, you should get 4-byte ints, i.e., MAX_INT = 2^31
- 1.)

Regards,
Jayesh

-----Original Message-----
From: Wei Yao [mailto:weiyao1 at googlemail.com] 
Sent: Tuesday, February 10, 2009 2:31 AM
To: Jayesh Krishna
Subject: about long int number

Dear Jayesh Krishna,

In  C  and  Fortran,  the  memory  allocation  for  integer number are
different:
1, in C int a, a takes 2  bytes with the range of -32768~32767.
2,  in  FORTRAN,  integer  a,  a  takes  4  bytes  with  the  range of
-2147483648~2147483647.

If I have an array with a length of 40000, I want to manipulate is use
MPI_REDUCE,  but  the  maximum  count  is  32767, how can I transfer a
40000-members array?
int MPI_Reduce(void* , void*, int count, MPI_Datatype, MPI_Op, int,
MPI_Comm);
                                ~~~~~~~maximum  32767

_______________________
Cheers,
Wei
>From FireSERT

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