MProbe Change Log

Prototypes of MProbe (under other names) date to 1994. The first publicly available, web-distributed version, (MProbe 1.01) dates to October 1996. Here are the changes since that time.

MProbe 5.0 re-release (December 19, 2003)

           No changes in MProbe functionality.

           Upgraded GAMS readers for compatibility with upcoming GAMS 21.3.

           Microsoft compatibility DLLs now included.

MProbe 5.0 (November 7, 2003)

           Added ability to read model files in the GAMS language.

           Added ability to read AMPL files directly without requiring the user to work within the AMPL environment.

           Re-implementated into the Microsoft .NET framework.

           Numerous minor bug fixes.

MProbe 4.0 (March 7, 2003)

           Points Workshop: allows import and export of points (e.g. from a solver), analyzes the properties of points (e.g. how close to feasibility) and the properties of the region around the point (e.g. how flat is the objective function in this region?). Can find an approximate feasible point (or even a feasible point under certain conditions).

           Ability to read in and edit MPS files directly.  Can display constraints and objectives read from MPS files in a natural equation format.

           An improved method for shrinking the variable bounds.  This is based on a variant of a projection algorithm (called the Constraint Consensus method), and is quite effective when many variables are initially unconstrained.

           An improved bootstrapping method for finding an initial feasible point for sampling inside a convex enclosure.

           Numerous minor bug fixes.

MProbe 3.2.2 (May 23, 2000)

           recompilation under a Microsoft Visual Studio service pack fixes many problems, including the bogus error message during installation.

           updated versions of the Student AMPL and AMPL interface library.

MProbe 3.2.1 (May, 2000)

Not released externally.

MProbe 3.2 (May 4, 2000)

           integer and binary variables are now snapped to appropriate values for the purposes of evaluating constraint effectiveness, if requested by the user.

           a number of new routines for tightening the bounds on the region of interest (normally the feasible region).     These include:

           analytic bounding methods for linear constraints,

           individual constraint sampling methods for nonlinear constraints,

           simultaneous constraint sampling methods for nonlinear constraints,

           finding an appropriate initial box size when sampling across the entire variable range is ineffective.

           much more effective routine for finding the first feasible point in a new convex sampling enclosure.

           new routine for approximating the prime analytic center to generating sampling rays when working with     hit-and-run methods for sampling general convex enclosures.

           in Constrained Region Workshop: new button for getting statistics on the sampling enclosure.

           in Constraints Workshop: new "show only" button for the enclosure constraints.

           function calls are now generic, so other modeling languages are straightforward to add.

           upgraded to Visual Basic 6.0 and Visual Studio 6.  Plotting utility is upgraded.

Fixes:

           tracing of profile errors for objective functions fixed.

           showing lists in another window (e.g. "show all nonlinear constraints") sometimes malfunctioned if the     "reverse" checkbox was checked.

           some constraint effectiveness calculations were incorrect.

           some spurious "line length" errors eliminated.

MProbe 3.0 (October 6, 1999)

           New status bar across the top. Clicking on the variable, constraint, or objective display opens the corresponding workshop.

           Objectives Workshop is now grid based, like the other workshops.

           Can now display objectives that contain a selected variable.

           Can now display specific points through the Variables Workshop (e.g. best points for the objectives), and show the max and min values of the variables sampled during a full analysis.

           Numerous new ways to profile, including between random points, capturing maximum and minimum points, gradient and reverse gradient directions, etc. There is now a grid display of the points used and discovered during profiling.

           Can now trace the profile plot, and the profile plot errors.

           Can now rightclick on the grid columns that can be changed in the Variables Workshop. Must first select (click), then a rightclick will bring up appropriate change form.

           Size-limiting widgets in professional edition removed. Should be able to handle very large models now, limited only by available memory.

           Revised Setup menu. Easier to change path to modeling language.

           New ability to sample inside any arbitrary convex enclosure formed by inequalities. This can greatly improve the accuracy of the estimates.

           Can now analyze enclosure constraint redundancy. New surface fraction analysis for necessary enclosure constraints.

           Added best extreme point and value identification for objectives.

           New progress form gives better indication of how long until operation is finished.

           Changed bounds on an integer or binary variable now snap to closest most restrictive integer.

           can read existing model files generated by AMPL. This is useful, if, say, your AMPL exists on a unix system, while MProbe exists on a windows machine.

           Can now read in points from an external file. Useful if you want to, say, profile starting from a particular point that was generated by another program (e.g. a solver).

           New copy and paste menu items. These work on any text boxes, and also on the grid displays.

MProbe 2.2.1 (June 14, 1999)

           Revised Statistics window to show more useful information.

           Fixes: (i) mis-identification of binary variables as general integers under some conditions, (ii) closing of all open windows when a new model is loaded.

MProbe 2.2 (May 28, 1999)

           Variables Workshop has added ability to select variables that are unbounded in one or both directions.

           Updated AMPL interface library now allows the use of external DLL files to define functions.

           Can now view the list of variables in an objective, just as for a constraint.

           A "selected objective" is now shown on the forms.

           Windows can be cascaded. Most windows are now fixed size.

           Fixes: (i) sorting variables or constraints no longer mixes up the "selected constraint" or "selected variable" listing.

MProbe 2.1 (May 19, 1999)

           The GUI has undergone a major revision. The main interface to the variables and constraints is a spreadsheet-like grid with new tools for selecting subsets to view (e.g. only constraints that have a mixture of real and integer/binary variables) and for user-controlled sorting.

           The Constrained Region Workshop now expressly takes into account constraints that are 100% effective (i.e. there is no feasible region) and that are 0% effective (their shape does not affect the conclusion as to whether the constrained region is convex or nonconvex).

           Buttons in the Constrained Region Workshop now take you directly to constraints having specified properties (e.g. list all constraints that contribute to a nonconvex constrained region).

           Fixes: (i) extremely large arguments can now be used with trig and other functions without difficulty, (ii) MProbe can be installed in any directory (you do not need to avoid directories having blanks in the name).

MProbe 2.02 (April 1998)

           Bug fix to the AMPL-solver interface library (hence changes to amplint.dll).

           addition of the variable bounds to the Sort Variables window.

MProbe 2.01 (March 1998)

           File ampldll32.dll changed to amplint.dll to avoid problems with the "8 dot 3" naming convention in some file systems and decompression utilities.

           Some cosmetic changes to the window and menu layouts

MProbe 2.0 (Feb. 1998)

           32-bit implementation. Much faster.

           recognition of quadratic functional forms

           Region Workshop: is the region formed by the constraints convex or nonconvex?

           estimates constraint "effectiveness": what fraction of the variable space does each constraint eliminate? Is it possible to satisfy an equality constraint in the current variable space?

           comments on objective shape effect: global optimum possible? local optimum likely?

           flexible sorting of information about constraints and variables. E.g. sort constraints by the number of integer/binary variables they contain, or by constraint effectiveness.

           some cosmetic changes to the window and menu layouts.

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