ST
Sparse Triplet Matrix File Format

ST is a data directory which contains examples of the "sparse triplet format", a simple data structure and a file format for storing sparse matrices.

The sparse triplet data structure simply records, for each nonzero entry of the matrix, the row, column and value. Thus, the information in the data structure might be

• M and N, the number of rows and columns in the (original full) matrix;
• NZ_NUM, the number of nonzero elements in the matrix;
• ROW(1:NZ_NUM), the row indices of the nonzero elements;
• COL(1:NZ_NUM), the column indices of the nonzero elements;
• VAL(1:NZ_NUM), the values of the nonzero elements;

The sparse triplet file format is an ASCII file of NZ_NUM lines, with each line corresponding to a nonzero entry of the matrix, and containing the row index, column index and value of that entry, separated by spaces.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Related Data and Programs:

DSP, a data directory which contains examples of DSP files, a sparse matrix file format, storing just (I,J,A(I,J)), and using one-based indexing.

LINPLUS, a C++ library which carries out simple manipulations of matrices in a variety of formats, including matrices stored in symmetric, banded, and sparse formats.

MGMRES, a C++ library which applies the restarted GMRES algorithm to solve a sparse linear system, by Lili Ju.

Example:

The 4 by 6 matrix

        11   0   0  14   0  16
         0  22   0   0  25  26
         0   0  33  34   0  36
        41   0  43  44   0  46
      

        0  0  11.0
        0  3  14.0
        0  5  16.0
        1  1  22.0
        1  3  25.0
        1  5  26.0
        2  2  33.0
        2  3  34.0
        2  5  36.0
        3  0  41.0
        3  2  43.0
        3  3  44.0
        3  5  46.0
      

ST File Characteristics:

• ASCII format;
• each line has the form I J A(I,J)
• the I and J indices are zero-based.

Reference:

1. Timothy Davis,
   Direct Methods for Sparse Linear Systems,
   SIAM, 2006.

Sample Files:

• 5by5.st, a 5 by 5 matrix.
• ash219.st
• bcsstk01.st
• bcsstk16.st
• fs_183_1.st
• kershaw.st, the 4 by 4 Kershaw matrix.
• lp_afiro.st
• mbeacxc.st
• t1.st
• west0067.st

You can go up one level to the DATA page.