Matrix Market
Read and Write Utilities

MM_IO, a MATLAB library which reads and writes files in the Matrix Market (MM) file format.


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


MM_IO is available in a C version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:

CC_IO, a MATLAB library which reads and writes sparse linear systems stored in the Compressed Column (CC) format.

DLAP_IO, a MATLAB library which reads and writes DLAP sparse matrix files;

HB_IO, a MATLAB library which reads and writes sparse matrices stored in the Harwell-Boeing format.

MM, a data directory which contains a description and examples of the Matrix Market format for storing matrices.


MM_TO_MSM, a MATLAB program which reads a Matrix Market file defining a sparse matrix, and creates a corresponding MATLAB sparse matrix data structure.

MM_TO_ST, a MATLAB program which reads the sparse matrix information from an MM Matrix Market file and writes a corresponding ST Sparse Triplet file.

MSM_TO_MM, a MATLAB program which writes a MATLAB sparse matrix to a Matrix Market file;

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

TEST_MAT, a MATLAB library which defines various test matrices.


  1. Ronald Boisvert, Roldan Pozo, Karin Remington,
    The Matrix Market Exchange Formats: Initial Design,
    National Institute of Standards and Technology,
    NISTIR 5935, December 1996

Source Code:

Last revised on 21 February 2019.