1 2 #include "src/mat/matimpl.h" /*I "petscmat.h" I*/ 3 4 #undef __FUNCT__ 5 #define __FUNCT__ "Mat_CheckCompressedRow" 6 /*@C 7 Mat_CheckCompressedRow - Determines whether the compressed row matrix format should be used. If 8 the format is to be used, this routine creates Mat_CompressedRow struct. 9 10 Compressed row format provides high performance routines by 11 taking advantage of zero rows. 12 13 Collective 14 15 Input Parameters: 16 + A - the matrix 17 . compressedrow - pointer to the struct Mat_CompressedRow 18 . ai - row pointer used by seqaij and seqbaij 19 - ratio - ratio of (num of zero rows)/m, used to determine if the compressed row format should be used 20 21 Level: developer 22 @*/ 23 PetscErrorCode Mat_CheckCompressedRow(Mat A,Mat_CompressedRow *compressedrow,PetscInt *ai,PetscReal ratio) 24 { 25 PetscErrorCode ierr; 26 PetscInt nrows,*cpi=PETSC_NULL,*ridx=PETSC_NULL,nz,i,row,m=A->m/A->bs; 27 28 PetscFunctionBegin; 29 if (!compressedrow->use) PetscFunctionReturn(0); 30 if (compressedrow->checked){ 31 if (!A->same_nonzero){ 32 ierr = PetscFree(compressedrow->i);CHKERRQ(ierr); 33 compressedrow->rindex = PETSC_NULL; 34 PetscLogInfo(A,"Mat_CheckCompressedRow: Mat structure might be changed. Free memory and recheck.\n"); 35 } else if (compressedrow->i == PETSC_NULL) { 36 /* Don't know why this occures. For safe, recheck. */ 37 PetscLogInfo(A,"Mat_CheckCompressedRow: compressedrow.checked, but compressedrow.i==null. Recheck.\n"); 38 } else { /* use compressedrow, checked, and A->same_nonzero = PETSC_TRUE. Skip check */ 39 PetscFunctionReturn(0); 40 } 41 } 42 compressedrow->checked = PETSC_TRUE; 43 44 /* compute number of zero rows */ 45 nrows = 0; 46 for (i=0; i<m; i++){ /* for each row */ 47 nz = ai[i+1] - ai[i]; /* number of nonzeros */ 48 if (nz == 0) nrows++; 49 } 50 /* if enough zero rows are found, use compressedrow data structure */ 51 if (nrows < ratio*m) { 52 compressedrow->use = PETSC_FALSE; 53 PetscLogInfo(A,"Mat_CheckCompressedRow: Found the ratio (num_zerorows %d)/(num_localrows %d) < %g. Do not use CompressedRow routines.\n",nrows,m,ratio); 54 } else { 55 compressedrow->use = PETSC_TRUE; 56 PetscLogInfo(A,"Mat_CheckCompressedRow: Found the ratio (num_zerorows %d)/(num_localrows %d) > %g. Use CompressedRow routines.\n",nrows,m,ratio); 57 58 /* set compressed row format */ 59 nrows = m - nrows; /* num of non-zero rows */ 60 ierr = PetscMalloc((2*nrows+1)*sizeof(PetscInt),&cpi);CHKERRQ(ierr); 61 ridx = cpi + nrows + 1; 62 row = 0; 63 cpi[0] = 0; 64 for (i=0; i<m; i++){ 65 nz = ai[i+1] - ai[i]; 66 if (nz == 0) continue; 67 cpi[row+1] = ai[i+1]; /* compressed row pointer */ 68 ridx[row++] = i; /* compressed row local index */ 69 } 70 compressedrow->nrows = nrows; 71 compressedrow->i = cpi; 72 compressedrow->rindex = ridx; 73 } 74 PetscFunctionReturn(0); 75 } 76