1 /*$Id: ij.c,v 1.38 2001/03/23 23:21:51 balay Exp $*/ 2 3 #include "src/mat/impls/aij/seq/aij.h" 4 5 #undef __FUNCT__ 6 #define __FUNCT__ "MatToSymmetricIJ_SeqAIJ" 7 /* 8 MatToSymmetricIJ_SeqAIJ - Convert a (generally nonsymmetric) sparse AIJ matrix 9 to IJ format (ignore the "A" part) Allocates the space needed. Uses only 10 the lower triangular part of the matrix. 11 12 Description: 13 Take the data in the row-oriented sparse storage and build the 14 IJ data for the Matrix. Return 0 on success,row + 1 on failure 15 at that row. Produces the ij for a symmetric matrix by only using 16 the lower triangular part of the matrix. 17 18 Input Parameters: 19 . Matrix - matrix to convert 20 . shiftin - the shift for the original matrix (0 or 1) 21 . shiftout - the shift required for the ordering routine (0 or 1) 22 23 Output Parameters: 24 . ia - ia part of IJ representation (row information) 25 . ja - ja part (column indices) 26 27 Notes: 28 Both ia and ja may be freed with PetscFree(); 29 This routine is provided for ordering routines that require a 30 symmetric structure. It is required since those routines call 31 SparsePak routines that expect a symmetric matrix. 32 */ 33 int MatToSymmetricIJ_SeqAIJ(int m,int *ai,int *aj,int shiftin,int shiftout,int **iia,int **jja) 34 { 35 int *work,*ia,*ja,*j,i,nz,row,col,ierr; 36 37 PetscFunctionBegin; 38 /* allocate space for row pointers */ 39 ierr = PetscMalloc((m+1)*sizeof(int),&ia);CHKERRQ(ierr); 40 *iia = ia; 41 ierr = PetscMemzero(ia,(m+1)*sizeof(int));CHKERRQ(ierr); 42 ierr = PetscMalloc((m+1)*sizeof(int),&work);CHKERRQ(ierr); 43 44 /* determine the number of columns in each row */ 45 ia[0] = shiftout; 46 for (row = 0; row < m; row++) { 47 nz = ai[row+1] - ai[row]; 48 j = aj + ai[row] + shiftin; 49 while (nz--) { 50 col = *j++ + shiftin; 51 if (col > row) { break;} 52 if (col != row) ia[row+1]++; 53 ia[col+1]++; 54 } 55 } 56 57 /* shiftin ia[i] to point to next row */ 58 for (i=1; i<m+1; i++) { 59 row = ia[i-1]; 60 ia[i] += row; 61 work[i-1] = row - shiftout; 62 } 63 64 /* allocate space for column pointers */ 65 nz = ia[m] + (!shiftin); 66 ierr = PetscMalloc(nz*sizeof(int),&ja);CHKERRQ(ierr); 67 *jja = ja; 68 69 /* loop over lower triangular part putting into ja */ 70 for (row = 0; row < m; row++) { 71 nz = ai[row+1] - ai[row]; 72 j = aj + ai[row] + shiftin; 73 while (nz--) { 74 col = *j++ + shiftin; 75 if (col > row) { break;} 76 if (col != row) {ja[work[col]++] = row + shiftout; } 77 ja[work[row]++] = col + shiftout; 78 } 79 } 80 ierr = PetscFree(work);CHKERRQ(ierr); 81 PetscFunctionReturn(0); 82 } 83 84 85 86