1 #ifndef lint 2 static char vcid[] = "$Id: ij.c,v 1.24 1996/10/16 21:08:02 balay Exp balay $"; 3 #endif 4 5 #include "src/mat/impls/aij/seq/aij.h" 6 7 #undef __FUNCTION__ 8 #define __FUNCTION__ "MatToSymmetricIJ_SeqAIJ" 9 /* 10 MatToSymmetricIJ_SeqAIJ - Convert a (generally nonsymmetric) sparse AIJ matrix 11 to IJ format (ignore the "A" part) Allocates the space needed. Uses only 12 the lower triangular part of the matrix. 13 14 Description: 15 Take the data in the row-oriented sparse storage and build the 16 IJ data for the Matrix. Return 0 on success, row + 1 on failure 17 at that row. Produces the ij for a symmetric matrix by only using 18 the lower triangular part of the matrix. 19 20 Input Parameters: 21 . Matrix - matrix to convert 22 . shiftin - the shift for the original matrix (0 or 1) 23 . shiftout - the shift required for the reordering routine (0 or 1) 24 25 Output Parameters: 26 . ia - ia part of IJ representation (row information) 27 . ja - ja part (column indices) 28 29 Notes: 30 $ Both ia and ja may be freed with PetscFree(); 31 $ This routine is provided for ordering routines that require a 32 $ symmetric structure. It is required since those routines call 33 $ SparsePak routines that expect a symmetric matrix. 34 */ 35 int MatToSymmetricIJ_SeqAIJ(int m,int *ai,int *aj,int shiftin, int shiftout, 36 int **iia, int **jja ) 37 { 38 int *work,*ia,*ja,*j,i, nz, row, col; 39 40 /* allocate space for row pointers */ 41 *iia = ia = (int *) PetscMalloc( (m+1)*sizeof(int) ); CHKPTRQ(ia); 42 PetscMemzero(ia,(m+1)*sizeof(int)); 43 work = (int *) PetscMalloc( (m+1)*sizeof(int) ); CHKPTRQ(work); 44 45 /* determine the number of columns in each row */ 46 ia[0] = shiftout; 47 for (row = 0; row < m; row++) { 48 nz = ai[row+1] - ai[row]; 49 j = aj + ai[row] + shiftin; 50 while (nz--) { 51 col = *j++ + shiftin; 52 if (col > row) { break;} 53 if (col != row) ia[row+1]++; 54 ia[col+1]++; 55 } 56 } 57 58 /* shiftin ia[i] to point to next row */ 59 for ( i=1; i<m+1; i++ ) { 60 row = ia[i-1]; 61 ia[i] += row; 62 work[i-1] = row - shiftout; 63 } 64 65 /* allocate space for column pointers */ 66 nz = ia[m] + (!shiftin); 67 *jja = ja = (int *) PetscMalloc( nz*sizeof(int) ); CHKPTRQ(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 PetscFree(work); 81 return 0; 82 } 83 84 85 86