New Versions and Release Dates

5/15/96: Version beta-1.0 announced.
10/18/96: Version beta-2.0 announced.
3/7/97: Version 1.0 announced.
11/2/97: Version 1.1 announced.
1/26/98: Windows Version 1.1 announced.
8/6/98: AMPL interface and PCxGUI (Java interface) announced.

Detailed Change Log for PCx (updated 1/10/06)

Date Change
5/15/96 Initial Release: version beta-1.0
5/17/96 Added Solaris executable and timing code
5/28/96 Added #include stdlib.h to readmps.c for Linux
7/09/96 Fixed bug in presolve.c
Date Change
10/18/96 Release of version beta-2.0:
... Includes dense column handling, many memory leak and bug fixes.
11/25/96 New ComputeADAT routine: greatly improves efficiency on some problems
Date Change
3/7/97 Release of version 1.0:
... Includes higher-order corrections, scaling, bug fixes.
6/25/97 Some memory leaks corrected
8/18/97 Fixed various minor leaks and bugs
... Provided cleaner interface to sparse Cholesky solvers
9/22/97 Fixed various leaks and changed input routine to always seek MPS file in current directory first
10/20/97 Fixed a few bugs in documentation
Date Change
11/2/97 Release of version 1.1:
... Includes hooks to incorporate alternative linear equations solvers, including WSSMP
12/8/97 Computational results added for WSSMP and Ng-Peyton versions
1/26/98 PCx 1.1 for Windows released
3/01/98 2 minor memory bugs fixed, new linux version built
3/10/98 PCx 1.1 for Windows - parameter file bug fixed
6/10/98 Added DOS version 1.1, unified parameter.c for DOS, Unix, all-C versions
8/6/98 AMPL interface and PCxGUI (Java interface) released.
8/12/99 Unix and C versions changed to accept problems with zero rows in the constraint matrix, and to improve efficiency of  initial matrix ordering routines. (We are working on improvements to the dense column handling, which will be released shortly.)
9/13/99 Bug fix in PCx Unix and  C versions. Bug affected instances with bound constraints in whch Gondzio correctors were used.
12/14/00 Fixed readmps.c to avoid core dumping on incorrect MPS input files.
2/27/01 A few fixes in line search heuristic and MPS file handling; affects only a few cases.
12/23/01 Fixed handling of "MI" in the BOUNDS section of MPS files; affects only cases in which MI variables have upper bounds other than 0.
2/26/02 Updated PCx-AMPL interface to fix some bugs in the interface, and document the installation process more thoroughly. Also created precompiled executables for Intel Solaris, Sun Solaris, and Linux.
2/28/02 Fixed bug in preprocessor for bounded variables in a singleton row.
11/4/03 Fixed another bug in preprocessor, again concerning row singletons.
11/5/03 Updated PCx-C (C version) to use latest version of fortran-to-C utility f2c.
3/19/04 Fixed minor bugs concerning handling of upper bounds (in PCx.c) and scaling (in scale.c). Unified the unix and Matlab-ready distributions.
5/11/04 Fixed hash.c to allow more than 1.3 million rows and columns; redefined allowable hash table sizes.
1/10/06 Fixed bug in memory allocation for array min_phi in PCx.c


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