Actual source code: ij.c
1: /*$Id: ij.c,v 1.38 2001/03/23 23:21:51 balay Exp $*/
3: #include src/mat/impls/aij/seq/aij.h
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.
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.
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)
23: Output Parameters:
24: . ia - ia part of IJ representation (row information)
25: . ja - ja part (column indices)
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;
38: /* allocate space for row pointers */
39: PetscMalloc((m+1)*sizeof(int),&ia);
40: *iia = ia;
41: PetscMemzero(ia,(m+1)*sizeof(int));
42: PetscMalloc((m+1)*sizeof(int),&work);
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: }
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: }
64: /* allocate space for column pointers */
65: nz = ia[m] + (!shiftin);
66: PetscMalloc(nz*sizeof(int),&ja);
67: *jja = ja;
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: }