Why not do something like this: double **A=new double*[N]; double *A_data new double [N*N];
for(int i=0;i<N;i++) A[i]=&A_data[i*N]; This way you have contiguous data (in A_data) but can access it as a 2D array using A[i][j]. (I haven't compiled this but I know we represent our matrices this way). On Thu, Oct 29, 2009 at 12:30 PM, Natarajan CS <csnata...@gmail.com> wrote: > Hi > thanks for the quick response. Yes, that is what I meant. I thought > there was no other way around what I am doing but It is always good to ask a > expert rather than assume! > > Cheers, > > C.S.N > > > On Thu, Oct 29, 2009 at 11:25 AM, Eugene Loh <eugene....@sun.com> wrote: > >> Natarajan CS wrote: >> >> Hello all, >>> Firstly, My apologies for a duplicate post in LAM/MPI list I have >>> the following simple MPI code. I was wondering if there was a workaround for >>> sending a dynamically allocated 2-D matrix? Currently I can send the matrix >>> row-by-row, however, since rows are not contiguous I cannot send the entire >>> matrix at once. I realize one option is to change the malloc to act as one >>> contiguous block but can I keep the matrix definition as below and still >>> send the entire matrix in one go? >>> >> >> You mean with one standard MPI call? I don't think so. >> >> In MPI, there is a notion of derived datatypes, but I'm not convinced this >> is what you want. A derived datatype is basically a static template of data >> and holes in memory. E.g., 3 bytes, then skip 7 bytes, then another 2 >> bytes, then skip 500 bytes, then 1 last byte. Something like that. Your 2d >> matrices differ in two respects. One is that the pattern in memory is >> different for each matrix you allocate. The other is that your matrix >> definition includes pointer information that won't be the same in every >> process's address space. I guess you could overcome the first problem by >> changing alloc_matrix() to some fixed pattern in memory for some r and c, >> but you'd still have pointer information in there that you couldn't blindly >> copy from one process address space to another. >> _______________________________________________ >> users mailing list >> us...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/users >> > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
