1 2 static char help[] = "Reads a matrix from PETSc binary file. Use for view or investigating matrix data structure. \n\n"; 3 /* 4 Example: 5 ./ex16 -f <matrix file> -a_mat_view draw -draw_pause -1 6 ./ex16 -f <matrix file> -a_mat_view ascii::ascii_info 7 */ 8 9 #include <petscmat.h> 10 int main(int argc,char **args) 11 { 12 Mat A,Asp; 13 PetscViewer fd; /* viewer */ 14 char file[PETSC_MAX_PATH_LEN]; /* input file name */ 15 PetscInt m,n,rstart,rend; 16 PetscBool flg; 17 PetscInt row,ncols,j,nrows,nnzA=0,nnzAsp=0; 18 const PetscInt *cols; 19 const PetscScalar *vals; 20 PetscReal norm,percent,val,dtol=1.e-16; 21 PetscMPIInt rank; 22 MatInfo matinfo; 23 PetscInt Dnnz,Onnz; 24 25 PetscCall(PetscInitialize(&argc,&args,(char*)0,help)); 26 PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank)); 27 28 /* Determine files from which we read the linear systems. */ 29 PetscCall(PetscOptionsGetString(NULL,NULL,"-f",file,sizeof(file),&flg)); 30 PetscCheck(flg,PETSC_COMM_WORLD,PETSC_ERR_USER,"Must indicate binary file with the -f option"); 31 32 /* Open binary file. Note that we use FILE_MODE_READ to indicate 33 reading from this file. */ 34 PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd)); 35 36 /* Load the matrix; then destroy the viewer. */ 37 PetscCall(MatCreate(PETSC_COMM_WORLD,&A)); 38 PetscCall(MatSetOptionsPrefix(A,"a_")); 39 PetscCall(MatSetFromOptions(A)); 40 PetscCall(MatLoad(A,fd)); 41 PetscCall(PetscViewerDestroy(&fd)); 42 PetscCall(MatGetSize(A,&m,&n)); 43 PetscCall(MatGetInfo(A,MAT_LOCAL,&matinfo)); 44 /*printf("matinfo.nz_used %g\n",matinfo.nz_used);*/ 45 46 /* Get a sparse matrix Asp by dumping zero entries of A */ 47 PetscCall(MatCreate(PETSC_COMM_WORLD,&Asp)); 48 PetscCall(MatSetSizes(Asp,m,n,PETSC_DECIDE,PETSC_DECIDE)); 49 PetscCall(MatSetOptionsPrefix(Asp,"asp_")); 50 PetscCall(MatSetFromOptions(Asp)); 51 Dnnz = (PetscInt)matinfo.nz_used/m + 1; 52 Onnz = Dnnz/2; 53 printf("Dnnz %d %d\n",Dnnz,Onnz); 54 PetscCall(MatSeqAIJSetPreallocation(Asp,Dnnz,NULL)); 55 PetscCall(MatMPIAIJSetPreallocation(Asp,Dnnz,NULL,Onnz,NULL)); 56 /* The allocation above is approximate so we must set this option to be permissive. 57 * Real code should preallocate exactly. */ 58 PetscCall(MatSetOption(Asp,MAT_NEW_NONZERO_LOCATION_ERR,PETSC_FALSE)); 59 60 /* Check zero rows */ 61 PetscCall(MatGetOwnershipRange(A,&rstart,&rend)); 62 nrows = 0; 63 for (row=rstart; row<rend; row++) { 64 PetscCall(MatGetRow(A,row,&ncols,&cols,&vals)); 65 nnzA += ncols; 66 norm = 0.0; 67 for (j=0; j<ncols; j++) { 68 val = PetscAbsScalar(vals[j]); 69 if (norm < val) norm = norm; 70 if (val > dtol) { 71 PetscCall(MatSetValues(Asp,1,&row,1,&cols[j],&vals[j],INSERT_VALUES)); 72 nnzAsp++; 73 } 74 } 75 if (!norm) nrows++; 76 PetscCall(MatRestoreRow(A,row,&ncols,&cols,&vals)); 77 } 78 PetscCall(MatAssemblyBegin(Asp,MAT_FINAL_ASSEMBLY)); 79 PetscCall(MatAssemblyEnd(Asp,MAT_FINAL_ASSEMBLY)); 80 81 percent=(PetscReal)nnzA*100/(m*n); 82 PetscCall(PetscPrintf(PETSC_COMM_SELF," [%d] Matrix A local size %d,%d; nnzA %d, %g percent; No. of zero rows: %d\n",rank,m,n,nnzA,percent,nrows)); 83 percent=(PetscReal)nnzAsp*100/(m*n); 84 PetscCall(PetscPrintf(PETSC_COMM_SELF," [%d] Matrix Asp nnzAsp %d, %g percent\n",rank,nnzAsp,percent)); 85 86 /* investigate matcoloring for Asp */ 87 PetscBool Asp_coloring = PETSC_FALSE; 88 PetscCall(PetscOptionsHasName(NULL,NULL,"-Asp_color",&Asp_coloring)); 89 if (Asp_coloring) { 90 MatColoring mc; 91 ISColoring iscoloring; 92 MatFDColoring matfdcoloring; 93 PetscCall(PetscPrintf(PETSC_COMM_WORLD," Create coloring of Asp...\n")); 94 PetscCall(MatColoringCreate(Asp,&mc)); 95 PetscCall(MatColoringSetType(mc,MATCOLORINGSL)); 96 PetscCall(MatColoringSetFromOptions(mc)); 97 PetscCall(MatColoringApply(mc,&iscoloring)); 98 PetscCall(MatColoringDestroy(&mc)); 99 PetscCall(MatFDColoringCreate(Asp,iscoloring,&matfdcoloring)); 100 PetscCall(MatFDColoringSetFromOptions(matfdcoloring)); 101 PetscCall(MatFDColoringSetUp(Asp,iscoloring,matfdcoloring)); 102 /*PetscCall(MatFDColoringView(matfdcoloring,PETSC_VIEWER_STDOUT_WORLD));*/ 103 PetscCall(ISColoringDestroy(&iscoloring)); 104 PetscCall(MatFDColoringDestroy(&matfdcoloring)); 105 } 106 107 /* Write Asp in binary for study - see ~petsc/src/mat/tests/ex124.c */ 108 PetscBool Asp_write = PETSC_FALSE; 109 PetscCall(PetscOptionsHasName(NULL,NULL,"-Asp_write",&Asp_write)); 110 if (Asp_write) { 111 PetscViewer viewer; 112 PetscCall(PetscPrintf(PETSC_COMM_SELF,"Write Asp into file Asp.dat ...\n")); 113 PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD,"Asp.dat",FILE_MODE_WRITE,&viewer)); 114 PetscCall(MatView(Asp,viewer)); 115 PetscCall(PetscViewerDestroy(&viewer)); 116 } 117 118 PetscCall(MatDestroy(&A)); 119 PetscCall(MatDestroy(&Asp)); 120 PetscCall(PetscFinalize()); 121 return 0; 122 } 123