Actual source code: ij.c

  1: #define PETSCMAT_DLL

 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: PetscErrorCode MatToSymmetricIJ_SeqAIJ(PetscInt m,PetscInt *ai,PetscInt *aj,PetscInt shiftin,PetscInt shiftout,PetscInt **iia,PetscInt **jja)
 34: {
 36:   PetscInt       *work,*ia,*ja,*j,i,nz,row,col;

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

 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:   }

 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:   }

 65:   /* allocate space for column pointers */
 66:   nz   = ia[m] + (!shiftin);
 67:   PetscMalloc(nz*sizeof(PetscInt),&ja);
 68:   *jja = ja;

 70:   /* loop over lower triangular part putting into ja */
 71:   for (row = 0; row < m; row++) {
 72:     nz = ai[row+1] - ai[row];
 73:     j  = aj + ai[row] + shiftin;
 74:     while (nz--) {
 75:       col = *j++ + shiftin;
 76:       if (col > row) { break;}
 77:       if (col != row) {ja[work[col]++] = row + shiftout; }
 78:       ja[work[row]++] = col + shiftout;
 79:     }
 80:   }
 81:   PetscFree(work);
 82:   return(0);
 83: }