1 /*$Id: ij.c,v 1.32 1999/06/30 23:51:02 balay Exp bsmith $*/ 2 3 #include "src/mat/impls/aij/seq/aij.h" 4 5 #undef __FUNC__ 6 #define __FUNC__ "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, 34 int **iia, int **jja ) 35 { 36 int *work,*ia,*ja,*j,i, nz, row, col,ierr; 37 38 PetscFunctionBegin; 39 /* allocate space for row pointers */ 40 *iia = ia = (int *) PetscMalloc( (m+1)*sizeof(int) );CHKPTRQ(ia); 41 ierr = PetscMemzero(ia,(m+1)*sizeof(int));CHKERRQ(ierr); 42 work = (int *) PetscMalloc( (m+1)*sizeof(int) );CHKPTRQ(work); 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 *jja = ja = (int *) PetscMalloc( nz*sizeof(int) );CHKPTRQ(ja); 67 68 /* loop over lower triangular part putting into ja */ 69 for (row = 0; row < m; row++) { 70 nz = ai[row+1] - ai[row]; 71 j = aj + ai[row] + shiftin; 72 while (nz--) { 73 col = *j++ + shiftin; 74 if (col > row) { break;} 75 if (col != row) {ja[work[col]++] = row + shiftout; } 76 ja[work[row]++] = col + shiftout; 77 } 78 } 79 ierr = PetscFree(work);CHKERRQ(ierr); 80 PetscFunctionReturn(0); 81 } 82 83 84 85