Der Matt, When I looked at the results, I found that there are some problems I couldn't understand.
First of all, I am working on a 72*4 matrix and as I said before, I want to have 72 different vectors having size 4 each, whose elements consist of the elements in the same row. And of course, all vectors should be in all processors (currently I am using 4 processors). When I use your scatter code, the output vector is divided into 4 parts for 4 processors and each vector consists of 18 row vectors whose elements are arranged in a way that if I want to find zeroth row vector, its elements are located in 0th,18th,36th,54th elements. So, isn't scatter's goal is to scatter all values to all processors? Furthermore, I am trying to use my vectors in that way but isn't there any possible way that I can reach my goal entirely? Thanks so much for your help, Eda Matthew Knepley <knep...@gmail.com>, 10 Haz 2020 Çar, 18:11 tarihinde şunu yazdı: > > On Wed, Jun 10, 2020 at 10:09 AM Eda Oktay <eda.ok...@metu.edu.tr> wrote: >> >> Dear Matt, >> >> I have one last question I believe. Up to creating a dense matrix I >> did what you've suggested. Thank you so much for that. >> >> I created a new dense matrix. Now, how should I wrap each vector in a >> MatDense again? I mean, what is wrapping vectors in a matrix? To put >> each of them again as rows? > > > I thought you need a dense matrix for something, since you started with one. > If you > do not, just do VecGetArray() on the vector from CreateToAll and use the > values. > > Thanks, > > Matt > >> >> Thanks! >> >> Eda >> >> Matthew Knepley <knep...@gmail.com>, 10 Haz 2020 Çar, 16:16 tarihinde >> şunu yazdı: >> > >> > On Wed, Jun 10, 2020 at 9:08 AM Eda Oktay <eda.ok...@metu.edu.tr> wrote: >> >> >> >> Dear Matt, >> >> >> >> Matthew Knepley <knep...@gmail.com>, 10 Haz 2020 Çar, 16:03 tarihinde >> >> şunu yazdı: >> >> > >> >> > On Wed, Jun 10, 2020 at 8:56 AM Eda Oktay <eda.ok...@metu.edu.tr> wrote: >> >> >> >> >> >> Hi all, >> >> >> >> >> >> I am trying to get all the rows of a parallel matrix as individual >> >> >> vectors. For instance, if I have 72*4 matrix, I want to get 72 >> >> >> different vectors having size 4. >> >> >> >> >> >> As far as I understood, MatGetRow is only for local rows, so >> >> >> MatGetOwnershipRange is used, however, when I tried this one, I >> >> >> couldn't get the whole and desired row vectors. >> >> >> >> >> >> In MatGetRow explanation, it is written that I should use >> >> >> MatCreateSubMatrices first, then use MatGetRow. But I couldn't >> >> >> understand to which extent I should create submatrices. I just need to >> >> >> have all 72 rows as 72 different vectors each having 4 elements. >> >> > >> >> > >> >> > 1) For sparse matrices, the storage is always divided by row, so that >> >> > values can only be retrieved for local rows with MatGetRow() >> >> > >> >> > 2) Is this matrix sparse? It sounds like it is dense. >> >> >> >> Matrix is dense. >> >> >> >> > >> >> > 3) Are you asking to get all matrix values on all processes? If so, I >> >> > think the easiest thing to do is first wrap a Vec around the >> >> > values, then use VecScatterToAll(), then wrap each one in a >> >> > MatDense again. >> >> >> >> Yes, I want all row vectors on all processes. In a dense matrix, >> >> should I still wrap a Vec around the values? I know I should use >> >> scatter but I couldn't even wrap a Vec around them. >> > >> > >> > I would do >> > >> > MatGetSize(&N); >> > MatGetLocalSize(&m); >> > >> > https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatDenseGetArray.html >> > <create vector of local size m*N> >> > >> > https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Vec/VecPlaceArray.html >> > >> > https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Vec/VecScatterCreateToAll.html >> > <do scatter> >> > >> > https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Vec/VecResetArray.html#VecResetArray >> > >> > https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatCreateDense.html >> > <use it> >> > <destroy matrix> >> > <destroy vector from CreateToAll> >> > >> > Thanks, >> > >> > Matt >> > >> >> >> >> Thanks so much! >> >> >> >> Eda >> >> >> >> > >> >> > Thanks, >> >> > >> >> > Matt >> >> > >> >> >> >> >> >> Thanks! >> >> >> >> >> >> Eda >> >> > >> >> > >> >> > >> >> > -- >> >> > What most experimenters take for granted before they begin their >> >> > experiments is infinitely more interesting than any results to which >> >> > their experiments lead. >> >> > -- Norbert Wiener >> >> > >> >> > https://www.cse.buffalo.edu/~knepley/ >> > >> > >> > >> > -- >> > What most experimenters take for granted before they begin their >> > experiments is infinitely more interesting than any results to which their >> > experiments lead. >> > -- Norbert Wiener >> > >> > https://www.cse.buffalo.edu/~knepley/ > > > > -- > What most experimenters take for granted before they begin their experiments > is infinitely more interesting than any results to which their experiments > lead. > -- Norbert Wiener > > https://www.cse.buffalo.edu/~knepley/
