Dear petsc team, Thank you for all your answers. I really appreciate.
Best regards, Medane > On 7 Feb 2025, at 15:22, Matthew Knepley <knep...@gmail.com> wrote: > > On Fri, Feb 7, 2025 at 8:20 AM medane.tchako...@univ-fcomte.fr > <mailto:medane.tchako...@univ-fcomte.fr> <medane.tchako...@univ-fcomte.fr > <mailto:medane.tchako...@univ-fcomte.fr>> wrote: >> Re: >> Please find below the output from the previous code, running on only one >> processor. >> >> Mat Object: 1 MPI process >> type: seqdense >> 7.2003197397953400e-01 3.9777780919128602e-01 9.8405227390177075e-01 >> 1.4405427480322786e-01 >> 6.1793966542126100e-02 7.3036588248200474e-02 7.3851607000756303e-01 >> 9.9650445216117589e-01 >> 1.0022337819588500e-02 1.0386628927366459e-01 4.0114727059134836e-01 >> 1.0677308875937896e-01 >> 1.4463931936456476e-01 2.5078039364333193e-01 5.2764865382548720e-01 >> 9.8905332488367748e-01 >> >> buffer[0] = 7.200320e-01 >> buffer[1] = 6.179397e-02 >> buffer[2] = 1.002234e-02 >> buffer[3] = 1.446393e-01 >> buffer[4] = 0.000000e+00 >> buffer[5] = 0.000000e+00 >> buffer[6] = 0.000000e+00 >> buffer[7] = 0.000000e+00 >> buffer[8] = 3.977778e-01 >> buffer[9] = 7.303659e-02 >> buffer[10] = 1.038663e-01 >> buffer[11] = 2.507804e-01 >> buffer[12] = 0.000000e+00 >> buffer[13] = 0.000000e+00 >> buffer[14] = 0.000000e+00 >> buffer[15] = 0.000000e+00 >> >> Mat Object: 1 MPI process >> type: seqdense >> 7.2003197397953400e-01 3.9777780919128602e-01 9.8405227390177075e-01 >> 1.4405427480322786e-01 >> 6.1793966542126100e-02 7.3036588248200474e-02 7.3851607000756303e-01 >> 9.9650445216117589e-01 >> 1.0022337819588500e-02 1.0386628927366459e-01 4.0114727059134836e-01 >> 1.0677308875937896e-01 >> 1.4463931936456476e-01 2.5078039364333193e-01 5.2764865382548720e-01 >> 9.8905332488367748e-01 >> 0.0000000000000000e+00 0.0000000000000000e+00 0.0000000000000000e+00 >> 0.0000000000000000e+00 >> 0.0000000000000000e+00 0.0000000000000000e+00 0.0000000000000000e+00 >> 0.0000000000000000e+00 >> 0.0000000000000000e+00 0.0000000000000000e+00 0.0000000000000000e+00 >> 0.0000000000000000e+00 >> 0.0000000000000000e+00 0.0000000000000000e+00 0.0000000000000000e+00 >> 0.0000000000000000e+00 >> >> >> I was expecting to get in “buffer”, only the data entries from R_part. >> Please, let me know if this is the excepted behavior and I’am missing >> something. > > As Jose already pointed out, SubMatrix() does not copy. It gives you a Mat > front end to the same data, but with changed sizes. In this case, the LDA is > 4, not 2, so when you iterate over the values, you skip over the ones you > don't want. > > Thanks, > > Matt > >> Thanks, >> Medane >> >> >> >> > On 7 Feb 2025, at 11:34, Pierre Jolivet <pie...@joliv.et >> > <mailto:pie...@joliv.et>> wrote: >> > >> > >> > >> >> On 7 Feb 2025, at 11:05 AM, medane.tchako...@univ-fcomte.fr >> >> <mailto:medane.tchako...@univ-fcomte.fr> wrote: >> >> >> >> >> >> Dear all, >> >> >> >> I have been experiencing incoherent data entries from this code below, >> >> when printing the array. Maybe I’am doing something wrong. >> > >> > What is incoherent? >> > Everything looks OK to me. >> > >> > Thanks, >> > Pierre >> > >> >> ---------------- >> >> >> >> PetscInt nlines = 8; // lines >> >> PetscInt ncols = 4; // columns >> >> PetscMPIInt rank; >> >> PetscMPIInt size; >> >> >> >> // Initialize PETSc >> >> PetscCall(PetscInitialize(&argc, &args, NULL, NULL)); >> >> PetscCallMPI(MPI_Comm_rank(MPI_COMM_WORLD, &rank)); >> >> PetscCallMPI(MPI_Comm_size(MPI_COMM_WORLD, &size)); >> >> >> >> Mat R_full; >> >> Mat R_part; >> >> PetscInt idx_first_row = 0; >> >> PetscInt idx_one_plus_last_row = nlines / 2; >> >> PetscCall(MatCreateDense(PETSC_COMM_WORLD, PETSC_DECIDE, PETSC_DECIDE, >> >> nlines, ncols, NULL, &R_full)); >> >> >> >> // Get sub matrix >> >> PetscCall(MatDenseGetSubMatrix(R_full, idx_first_row, >> >> idx_one_plus_last_row, PETSC_DECIDE, PETSC_DECIDE, &R_part)); >> >> // Add entries to sub matrix >> >> MatSetRandom(R_part, NULL); >> >> //View sub matrix >> >> PetscCall(MatView(R_part, PETSC_VIEWER_STDOUT_WORLD)); >> >> >> >> // Get array from sub matrix and print entries >> >> PetscScalar *buffer; >> >> PetscCall(MatDenseGetArray(R_part, &buffer)); >> >> PetscInt idx_end = (nlines/2) * ncols; >> >> >> >> for (int i = 0; i < idx_end; i++) >> >> { >> >> PetscPrintf(PETSC_COMM_SELF, "buffer[%d] = %e \n", i, buffer[i]); >> >> } >> >> >> >> //Restore array to sub matrix >> >> PetscCall(MatDenseRestoreArray(R_part, &buffer)); >> >> // Restore sub matrix >> >> PetscCall(MatDenseRestoreSubMatrix(R_full, &R_part)); >> >> // View the initial matrix >> >> PetscCall(MatView(R_full, PETSC_VIEWER_STDOUT_WORLD)); >> >> >> >> PetscCall(MatDestroy(&R_full)); >> >> >> >> PetscCall(PetscFinalize()); >> >> return 0; >> >> >> >> ---------------- >> >> >> >> >> >> Thanks >> >> Medane >> > >> > >> > > > > -- > 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://urldefense.us/v3/__https://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!aW67hycVSXmRHgmoXNGV0fVjZ4HM7XloTvLw0b1d9peGDnJGYOm6nKgJPy53qErREjKHhwJybk0bAXiSQY7f9RreQX1Aik1VZBB7CIDA$ > > <https://urldefense.us/v3/__http://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!aW67hycVSXmRHgmoXNGV0fVjZ4HM7XloTvLw0b1d9peGDnJGYOm6nKgJPy53qErREjKHhwJybk0bAXiSQY7f9RreQX1Aik1VZKEXJSu-$ > >
