1cb512458SBarry Smith #ifndef lint 2*416022c9SBarry Smith static char vcid[] = "$Id: ij.c,v 1.10 1995/09/21 20:10:16 bsmith Exp bsmith $"; 3cb512458SBarry Smith #endif 4d6dfbf8fSBarry Smith 52d9e4a2aSBarry Smith #include "aij.h" 62d9e4a2aSBarry Smith 72d9e4a2aSBarry Smith /* 8ec8511deSBarry Smith MatToSymmetricIJ_SeqAIJ - Convert a sparse AIJ matrix to IJ format 92d9e4a2aSBarry Smith (ignore the "A" part) 102d9e4a2aSBarry Smith Allocates the space needed. Uses only the lower triangular 112d9e4a2aSBarry Smith part of the matrix. 122d9e4a2aSBarry Smith 132d9e4a2aSBarry Smith Description: 142d9e4a2aSBarry Smith Take the data in the row-oriented sparse storage and build the 152d9e4a2aSBarry Smith IJ data for the Matrix. Return 0 on success, row + 1 on failure 162d9e4a2aSBarry Smith at that row. Produces the ij for a symmetric matrix by only using 172d9e4a2aSBarry Smith the lower triangular part of the matrix. 182d9e4a2aSBarry Smith 192d9e4a2aSBarry Smith Input Parameters: 202d9e4a2aSBarry Smith . Matrix - matrix to convert 212d9e4a2aSBarry Smith 222d9e4a2aSBarry Smith Output Parameters: 232d9e4a2aSBarry Smith . ia - ia part of IJ representation (row information) 242d9e4a2aSBarry Smith . ja - ja part (column indices) 252d9e4a2aSBarry Smith 262d9e4a2aSBarry Smith Notes: 27464493b3SBarry Smith $ Both ia and ja maybe freed with PETSCFREE(); 28464493b3SBarry Smith $ This routine is provided for ordering routines that require a 29464493b3SBarry Smith $ symmetric structure. It is used in SpOrder (and derivatives) since 30464493b3SBarry Smith $ those routines call SparsePak routines that expect a symmetric 31464493b3SBarry Smith $ matrix. 322d9e4a2aSBarry Smith */ 33*416022c9SBarry Smith int MatToSymmetricIJ_SeqAIJ( Mat_SeqAIJ *A, int **iia, int **jja ) 342d9e4a2aSBarry Smith { 35*416022c9SBarry Smith int *work,*ia,*ja,*j,i, nz, n = A->m, row, wr, col, shift = A->indexshift; 362d9e4a2aSBarry Smith 372d9e4a2aSBarry Smith /* allocate space for row pointers */ 3878b31e54SBarry Smith *iia = ia = (int *) PETSCMALLOC( (n+1)*sizeof(int) ); CHKPTRQ(ia); 39*416022c9SBarry Smith PetscZero(ia,(n+1)*sizeof(int)); 4078b31e54SBarry Smith work = (int *) PETSCMALLOC( (n+1)*sizeof(int) ); CHKPTRQ(work); 412d9e4a2aSBarry Smith 422d9e4a2aSBarry Smith /* determine the number of columns in each row */ 432d9e4a2aSBarry Smith ia[0] = 1; 442d9e4a2aSBarry Smith for (row = 0; row < n; row++) { 45*416022c9SBarry Smith nz = A->i[row+1] - A->i[row]; 46*416022c9SBarry Smith j = A->j + A->i[row] + shift; 472d9e4a2aSBarry Smith while (nz--) { 48dbb450caSBarry Smith col = *j++ + shift; 49*416022c9SBarry Smith if ( col > row ) { break;} 502d9e4a2aSBarry Smith if (col != row) ia[row+1]++; 512d9e4a2aSBarry Smith ia[col+1]++; 522d9e4a2aSBarry Smith } 532d9e4a2aSBarry Smith } 542d9e4a2aSBarry Smith 552d9e4a2aSBarry Smith /* shift ia[i] to point to next row */ 562d9e4a2aSBarry Smith for ( i=1; i<n+1; i++ ) { 572d9e4a2aSBarry Smith row = ia[i-1]; 582d9e4a2aSBarry Smith ia[i] += row; 592d9e4a2aSBarry Smith work[i-1] = row - 1; 602d9e4a2aSBarry Smith } 612d9e4a2aSBarry Smith 622d9e4a2aSBarry Smith /* allocate space for column pointers */ 63dbb450caSBarry Smith nz = ia[n] + (!shift); 6478b31e54SBarry Smith *jja = ja = (int *) PETSCMALLOC( nz*sizeof(int) ); CHKPTRQ(ja); 652d9e4a2aSBarry Smith 662d9e4a2aSBarry Smith /* loop over lower triangular part putting into ja */ 672d9e4a2aSBarry Smith for (row = 0; row < n; row++) { 68*416022c9SBarry Smith nz = A->i[row+1] - A->i[row]; 69*416022c9SBarry Smith j = A->j + A->i[row] + shift; 702d9e4a2aSBarry Smith while (nz--) { 71dbb450caSBarry Smith col = *j++ + shift; 72*416022c9SBarry Smith if ( col > row ) { break;} 73*416022c9SBarry Smith if (col != row) {wr = work[col]; work[col] = wr + 1; ja[wr] = row + 1; } 742d9e4a2aSBarry Smith wr = work[row]; work[row] = wr + 1; 752d9e4a2aSBarry Smith ja[wr] = col + 1; 762d9e4a2aSBarry Smith } 772d9e4a2aSBarry Smith } 7878b31e54SBarry Smith PETSCFREE(work); 792d9e4a2aSBarry Smith return 0; 802d9e4a2aSBarry Smith } 812d9e4a2aSBarry Smith 82