1 Jul 1998 
NEP Files in Matrix Market Format Corrected. Several data files in the NEP collection were recently found to contain corrupt data. We have isolated the problem, which occurred in 28 of the Matrix Market formatted data files (*.mtx.gz) within 9 NEP sets, and replaced these files with corrected versions. We regret any inconvenience this may have caused. (Note: The data stored in HarwellBoeing format is correct and unchanged.) The affected matrices are as follows. Set MVMBWM: bwm200, bwm2000. Set MVMMCD: cdde1, cdde2, cdde3, cdde4, cdde5, cdde6. Set MVMODE: odep400a, odep400b. Set MVMRWK: rw136, rw496, rw5151. Set MVMTLS: tols1090, tols2000, tols340, tols4000, tols90. Set OLMSTEAD: olm100, olm1000, olm2000, olm500, olm5000. Set ROBOTICS: rbs480a, rbs480b. Set STOCH: lop163. Set TUBULAR: tub100, tub1000. A complete collection of corrected data (tar file of gzipped data files, 717 Kb) is available for download. 
25 Jun 1998 
New Entries Added to Bibliography. Approximately 40 new entries have been added to the Matrix Market bibliography. The new entries represent articles in the SIAM Journal of Scientific Computing, the SIAM Journal of Matrix Analysis and Applications, the Journal of Computational and Applied Mathematics and the IMA Journal of Numerical Analysis for the years 199098 which describe computational experiments using matrices which are included in the Matrix Market. The bibliography now includes about 210 entries. Thanks to student volunteer Brianna Blaser of Richard Montgomery High School in Rockville, MD for doing the literature search and preparing the BibTeX entries. 
29 Jan 1998 
Search Tool Recognizes Symmetric Sparsity Structure. The Matrix Market Search Tool now allows one to differentiate between sparse matrices with and without symmetric nonzero structures. In particular, one can specify either sparse unsymmetric or sparse symmetric in the Nonzero Structure field. (The choice sparse is still available and includes both these cases.) Note that setting Nonzero Structure to sparse symmetric does not imply that the matrix is numerically symmetric, only that the element A(i,j) is nonzero if and only if A(j,i) is nonzero. 
10 Nov 1997 
CYLSHELL Matrices Revised. The following matrices have been withdrawn from CYLSHELL: C1RMQ4M1, C2RMT3M1, C3RMQ4M1, C1RMT3M1, C3DKQ4M2, C3RMT3M1, C2RMQ4M1, C3DKT3M2, C3RMT3M3. If you have taken copies of these matrix files please discard them. These matrices have been replaced by new matrices whose names begin with S instead of C. The new matrices are identical to the previous ones except that they are represented using 17 decimal digits of precision. Some of the previous matrices were indefinite in the 6 digits in which they were represented. 
10 Nov 1997 
Clearer Matrix Statistics. Matrix home pages have been regenerated with new links to help information on matrix statistics. The help text should clarify the terminology used in the labeling, as well as provide additional background on how the data was computed. Condition number estimates have also been been included for 95 additional matrices, extending the size matrix for which this data is provided to order 13668. These were computed using the Matlab function condest. 
6 Aug 1997 
VRML Cityplots for 110 Additional Matrices Included. One hundred and ten additional VRML models of matrix cityplots have been added to the Matrix Market. Cityplots are threedimensional bar charts of matrix entries. The VRML versions allow users with compatible browsers or plugins to manipulate these images as 3D objects. The new additions represent matrices with from 4,000 to 24,000 entries, larger than those previously included. In order to reduce their size, only the front face of the 3D bars representing each elemet are represented in these files. This bring the number of matrices with VRML models to 232. 
23 July 1997 
Visualizations of 26 FEM Meshes Included. Visualizations of the meshes from the finite element discretizations which lead to 26 of the matrices in the DWT set of the HarwellBoeing collection have been included in the Matrix Market. Both static visualizations and dynamic VRML models are included in each case. See, for example, matrix DWT 245. These were generated from data supplied by Gordon Everstine of the Naval Surface Warfare Center, Carderock Division. 
7 July 1997 
Nine Matrices from Analysis of Cylindrical Shells Added. Nine new symmetric positive definite matrices from the finite element analysis of cylindrical shells have been contributed to the Matrix Market by Reijo Kouhia of the Helsinki University of Technology. The new CYLSHELL set contains the largest matrix in the Matrix Market to date, a 90,449 by 90,449 matrix with 2.5 million entries obtained from a finite element discretization of a cylindrical shell with a 150 x 100 quadrilateral mesh. 
9 June 1997 
Fiftythree Additional VRML CityPlots Added. Fiftythree additional VRML models of matrix cityplots have been added to the Matrix Market. Cityplots are threedimensional bar charts of matrix entries. The VRML versions allow users with compatible browsers or plugins to manipulate these images as 3D objects. The new additions bring the number of matrices with VRML models to 122. 
9 June 1997 
Matrix Structure Plots Improved. Structure plots for all matrices of order less than 351 have been replaced by new versions which more faithfully display nonzero structure. 
16 May 1997 
Version 3 of the Matrix Market Innaugurated. The Matrix Market has undergone a variety of changes in the past few months. These have now been incorporated into the release of Version 3. Among these are the inclusion of matrix generation software and services, new matrix visualizations, as well as a new home page design. 
15 May 1997 
Matrix Cityplots Included. Matrix cityplots, an alternate visualization of matrix structure, is now included in most matrix home pages. A cityplot is a threedimensional bar chart of the matrix elements. Each element is represented by a bar whose height and color are linearly scaled to the element value. This provides a quick visual impression of both sparsity structure and relative sizes of elements. We have also begun experimenting with the use of VRML to manipulate these 3D images. Such VRML cityplots have been produced for 69 matrices. 
5 May 1997 
Assembled Versions of HarwellBoeing Matrices Withdrawn. Versions of elemental matrices in the HarwellBoeing format which had been assembled and made available in Matrix Market format refected an assembly which differed from what the contributor intended and have been withdrawn. The affected matrices are CEGB2802, CEGB2919, CEGB3024, CEGB3306, LAP 25, LOCK 700, LOCK1074, LOCK2232, LOCK3491, and MAN 5976. Please discard such files if you have taken copies. The HarwellBoeing file remains, but requires proper interpretation. 
17 Apr 1997 
Interactive LAPACK Matrix Generator Released. A Web formsbased interface to the LAPACK random test matrix generators DLATMR/ZLATMR has been added to the Matrix Market. This provides realtime generation of test matrices with 20 configurable parameters to select desired matrix properties. Matrices of size up to 250x250 can be generated this way; the matrix generation code itself can be downloaded to generate larger matrices locally. 
13 Mar 1997 
Matrix Market Deli unveiled. "Test matrices made to order ... while you wait." The Matrix Market Deli (MMDELI) is an experimental collection of Java applets which will run in your Web browser to generate matrices satisfying various properties that you specify. The matrices may be viewed numerically and graphically, or written to a file in Matrix Market format. Most of the generators in the MMDELI were adapted from Nicholas Higham's Test Matrix Toolbox for MATLAB. 
13 Mar 1997 
Matrix generators now supported. The Matrix Market database has been restructured to support matrix generation software as well as static matrices. Generators are treated much like (matrix) sets, but have additional attributes similar to those of individual matrices. The Matrix Market search tool will now locate appropriate generators as well as matrices. The matrix generators associated with the NEP collection are now supported in this way. 
3 Mar 1997 
Glossary added. A brief glossary of terms from linear algebra which are used to describe matrices in the Matrix Market is now available. 
31 Jan 1997 
Bibliography expanded. The bibliography of articles related to the matrices indexed by the Matrix Market has been expanded to nearly 150 entries, and now includes all of the references associated with the NEP collection. 
3 Jan 1997 
Index of matrix names added. An alphabetical list of matrices included in the Matrix Market is now available. This is meant to aid users who already know the names of the matrices they want. If the name is unknown, then the Matrix Market search tool is prefered. 
10 Dec 1996 
Conversion errors corrected. Due to a conversion routine error, several matrices stored in Matrix Market coordinate format downloaded between 18 October 1996 and 10 Dec 1996 may have contained incorrect data. All of the affected files have been regenerated. None of the matrices distributed in HarwellBoeing format are affected. 
3 Dec 1996 
NEP Collection Added. The Nonsymmetric Eigenvalue Problem (NEP) collection developed by Zhaojun Bai, David Day, James Demmel and Jack Dongarra has been installed in the Matrix Market. These include 73 challenging matrices from ordinary and generalized eigenproblems taken from a variety of applications. In some cases, Fortran subroutines which generate the test problems are also available. 
30 Oct 1996 
DRIVCAV Set Revised. A new version of DRIVCAV has replaced the set originally made available in the Matrix Market. According to contributor Andrew Chapman of the University of Minnesota, the new set uses a slightly different formulation of the driven cavity problem, yielding matrices with better properties (e.g., convective part is symmetric rather than skew symmetric, removal of Dirichlet nodes to give symmetric structure, etc.) The old DRIVCAV matrices continue to be available in the set DRIVCAV_OLD. 
18 Oct 1996 
First Major Update to Matrix Market. This version contains

18 May 1996 
Error in LANPRO data. Matrices in the LANPRO subcollection (NOS1  NOS7) downloaded in coordinate text file format before May 18, 1996 contained incorrect data. These files have now been corrected. The original HarwellBoeing format files were unaffected. 
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Last change in this page : 18 December 2000. .