Actual source code: matio.c

  1: #define PETSCMAT_DLL

  3: /* 
  4:    This file contains simple binary read/write routines for matrices.
  5:  */

 7:  #include private/matimpl.h

 11: /*@C
 12:    MatLoad - Loads a matrix that has been stored in binary format
 13:    with MatView().  The matrix format is determined from the options database.
 14:    Generates a parallel MPI matrix if the communicator has more than one
 15:    processor.  The default matrix type is AIJ.

 17:    Collective on PetscViewer

 19:    Input Parameters:
 20: +  viewer - binary file viewer, created with PetscViewerBinaryOpen()
 21: -  outtype - type of matrix desired, for example MATSEQAIJ,
 22:               MATMPISBAIJ etc.  See types in petsc/include/petscmat.h.

 24:    Output Parameters:
 25: .  newmat - new matrix

 27:    Basic Options Database Keys:
 28: +    -matload_type seqaij   - AIJ type
 29: .    -matload_type mpiaij   - parallel AIJ type
 30: .    -matload_type seqbaij  - block AIJ type
 31: .    -matload_type mpibaij  - parallel block AIJ type
 32: .    -matload_type seqsbaij - block symmetric AIJ type
 33: .    -matload_type mpisbaij - parallel block symmetric AIJ type
 34: .    -matload_type seqdense - dense type
 35: .    -matload_type mpidense - parallel dense type
 36: -    -matload_symmetric - matrix in file is symmetric

 38:    More Options Database Keys:
 39:    Used with block matrix formats (MATSEQBAIJ,  ...) to specify
 40:    block size
 41: .    -matload_block_size <bs>

 43:    Level: beginner

 45:    Notes:
 46:    MatLoad() automatically loads into the options database any options
 47:    given in the file filename.info where filename is the name of the file
 48:    that was passed to the PetscViewerBinaryOpen(). The options in the info
 49:    file will be ignored if you use the -viewer_binary_skip_info option.

 51:    In parallel, each processor can load a subset of rows (or the
 52:    entire matrix).  This routine is especially useful when a large
 53:    matrix is stored on disk and only part of it existsis desired on each
 54:    processor.  For example, a parallel solver may access only some of
 55:    the rows from each processor.  The algorithm used here reads
 56:    relatively small blocks of data rather than reading the entire
 57:    matrix and then subsetting it.

 59:    Notes for advanced users:
 60:    Most users should not need to know the details of the binary storage
 61:    format, since MatLoad() and MatView() completely hide these details.
 62:    But for anyone who's interested, the standard binary matrix storage
 63:    format is

 65: $    int    MAT_FILE_COOKIE
 66: $    int    number of rows
 67: $    int    number of columns
 68: $    int    total number of nonzeros
 69: $    int    *number nonzeros in each row
 70: $    int    *column indices of all nonzeros (starting index is zero)
 71: $    PetscScalar *values of all nonzeros

 73:    PETSc automatically does the byte swapping for
 74: machines that store the bytes reversed, e.g.  DEC alpha, freebsd,
 75: linux, Windows and the paragon; thus if you write your own binary
 76: read/write routines you have to swap the bytes; see PetscBinaryRead()
 77: and PetscBinaryWrite() to see how this may be done.

 79: .keywords: matrix, load, binary, input

 81: .seealso: PetscViewerBinaryOpen(), MatView(), VecLoad()

 83:  @*/
 84: PetscErrorCode  MatLoad(PetscViewer viewer, const MatType outtype,Mat *newmat)
 85: {
 86:   Mat            factory;
 88:   PetscTruth     isbinary,flg;
 89:   MPI_Comm       comm;
 90:   PetscErrorCode (*r)(PetscViewer, const MatType,Mat*);
 91:   char           mtype[256];
 92:   const char     *prefix;

 97:   *newmat = 0;

 99:   PetscObjectGetOptionsPrefix((PetscObject)viewer,(const char **)&prefix);
100:   PetscTypeCompare((PetscObject)viewer,PETSC_VIEWER_BINARY,&isbinary);
101:   if (!isbinary) {
102:     SETERRQ(PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");
103:   }

105:   PetscOptionsGetString(prefix,"-mat_type",mtype,256,&flg);
106:   if (flg) {
107:     outtype = mtype;
108:   }
109:   PetscOptionsGetString(prefix,"-matload_type",mtype,256,&flg);
110:   if (flg) {
111:     outtype = mtype;
112:   }
113:   if (!outtype) outtype = MATAIJ;

115:   PetscObjectGetComm((PetscObject)viewer,&comm);
116:   MatCreate(comm,&factory);
117:   MatSetSizes(factory,0,0,0,0);
118:   MatSetType(factory,outtype);
119:   r = factory->ops->load;
120:   MatDestroy(factory);
121:   if (!r) SETERRQ1(PETSC_ERR_SUP,"MatLoad is not supported for type: %s",outtype);

123:   PetscLogEventBegin(MAT_Load,viewer,0,0,0);
124:   (*r)(viewer,outtype,newmat);
125:   PetscLogEventEnd(MAT_Load,viewer,0,0,0);

127:   flg  = PETSC_FALSE;
128:   PetscOptionsGetTruth(prefix,"-matload_symmetric",&flg,PETSC_NULL);
129:   if (flg) {
130:     MatSetOption(*newmat,MAT_SYMMETRIC,PETSC_TRUE);
131:     MatSetOption(*newmat,MAT_SYMMETRY_ETERNAL,PETSC_TRUE);
132:   }
133:   return(0);
134: }