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:

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.

ST_IO, a C library which reads and writes sparse linear systems stored in the Sparse Triplet (ST) format.

ST_TO_CC, a C library which converts sparse matrix data from Sparse Triplet (ST) format to Compressed Column (CC) format.

ST_TO_HB, a FORTRAN90 program which converts a sparse matrix file from Sparse Triplet (ST) format to Harwell Boeing (HB) format;

ST_TO_MM, a MATLAB program which converts a sparse matrix file from Sparse Triplet (ST) format to Matrix Market (MM) format;

ST_TO_MSM, a MATLAB program which reads a Sparse Triplet (ST) file and creates a corresponding MATLAB Sparse Matrix (MSM).

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:

• a5by5_st.txt, a 5 by 5 matrix with 13 entries, zero-based indexes.
• ash219_st.txt, a 219 by 85 matrix with 438 entries, zero-based indexes.
• bcsstk01_st.txt, a 48 by 48 matrix with 224 entries, zero-based indexes.
• bcsstk16_st.txt, a 4884 by 4884 matrix with 147631 entries, zero-based indexes.
• fs_183_1_st.txt, a 183 by 183 matrix with 1069 entries, zero-based indexes.
• kershaw_st.txt, the 4 by 4 Kershaw matrix with 12 entries, zero-based indexes.
• lp_afiro_st.txt, the 27 by 51 matrix with 102 entries, zero-based indexes.
• mbeacxc_st.txt, the 491 by 490 matrix with 49920 entries, zero-based indexes.
• t1_st.txt, the 4 by 4 matrix with 10 entries, zero-based indexes.
• west0067_st.txt, the 67 by 67 matrix with 299 entries, zero-based indexes.

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