Date: 2013-07-02T14:41:32+00:00

Actual source code: ij.c
petsc-3.4.2 2013-07-02

      2: #include <../src/mat/impls/aij/seq/aij.h>

      6: /*
      7:   MatToSymmetricIJ_SeqAIJ - Convert a (generally nonsymmetric) sparse AIJ matrix
      8:            to IJ format (ignore the "A" part) Allocates the space needed. Uses only
      9:            the lower triangular part of the matrix.

     11:     Description:
     12:     Take the data in the row-oriented sparse storage and build the
     13:     IJ data for the Matrix.  Return 0 on success,row + 1 on failure
     14:     at that row. Produces the ij for a symmetric matrix by only using
     15:     the lower triangular part of the matrix.

     17:     Input Parameters:
     18: .   Matrix - matrix to convert
     19: .   shiftin - the shift for the original matrix (0 or 1)
     20: .   shiftout - the shift required for the ordering routine (0 or 1)

     22:     Output Parameters:
     23: .   ia     - ia part of IJ representation (row information)
     24: .   ja     - ja part (column indices)

     26:     Notes:
     27:     Both ia and ja may be freed with PetscFree();
     28:     This routine is provided for ordering routines that require a
     29:     symmetric structure.  It is required since those routines call
     30:     SparsePak routines that expect a symmetric  matrix.
     31: */
     32: PetscErrorCode MatToSymmetricIJ_SeqAIJ(PetscInt m,PetscInt *ai,PetscInt *aj,PetscInt shiftin,PetscInt shiftout,PetscInt **iia,PetscInt **jja)
     33: {
     35:   PetscInt       *work,*ia,*ja,*j,i,nz,row,col;

     38:   /* allocate space for row pointers */
     39:   PetscMalloc((m+1)*sizeof(PetscInt),&ia);
     40:   *iia = ia;
     41:   PetscMemzero(ia,(m+1)*sizeof(PetscInt));
     42:   PetscMalloc((m+1)*sizeof(PetscInt),&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(PetscInt),&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: }