
From:  Chen, Jenny 
Subject:  [Helpglpk] Questions about the GLPK Package 
Date:  Fri, 15 Jan 2010 02:05:50 +0300 
Dear GLPK Personnel: ICF came across the GLPK package via recommendations from operations research analysts working within the Office of Integrated Analysis and Forecasting within the Energy Information Administration (EIA). ICF is helping the EIA conduct a survey of solvers that can serve as costeffective alternatives to solver engines such as DASH and CPLEX. Below, I #8217;ve listed several questions that I have about GLPK. If you can take a moment to answer them, I would greatly appreciate it. Thank you! Software Requirements What are the input/output capabilities for the solver? Does the solver have the capability for input/output files of the following formats: (a) delimited text (i.e. csv, etc); (b) structured text (i.e. xml, etc); (c) spreadsheets (i.e. xls, xlsx); (d) databases (i.e. Access databases); (e) proprietary format? Does the solver support other database providers (e.g. Microsoft SQL Server, Oracle, MySQL, or PostgreSQL)? What database drivers does the solver support? (e.g. native driver, OLE, ODBC) Do external programs become integrated with the solver through: (a) static linkage; (b) dynamic linkage (i.e. DLL, shared objects, etc); (c) COM, DCOM, OLE; (d) RPC, network clientserver, other or (e) all of the above, depending on the type of external program (If so, can you go into details?)? Would the licensed user have access to the source code so as to alter capabilities of the solver to meet users #8217; needs? If not, what addin capabilities are available to licensed users? How are upgrades made available to licensed users? Would the solver provide them to licensed users for free for 1 year after purchase of a license? ICF is interested in learning more about how the solver outputs runtime debug information. For example, if one of ICF #8217;s programmers writes source code for a new model, how would he or she output runtime errors and warnings? Does the solver provide a function to output debug information to a text file, database, system log, etc, or some combination of multiple output mediums? What is the cost of a license per user? What are the operating system requirements for the solver? (e.g. edition of Windows operating system, 32 or 64bit? RAM required? Disk space required?) With which programming language does the solver have an interface? What kind of interfaces are these? (e.g. interactive, objectoriented, etc) Calculation Requirements How many variables and constraints can the solver accommodate? Can you provide your answer by type of problem? (e.g. x and y number of variables and constrain for a linear and quadratic programming problem, respectively) Size limitations #8211; what are the size limitations of the model in terms of memory, and dimensions of arrays? Compare runs #8211; does the user interface allow the use of comparing runs What is the solver #8217;s graphing capability? How many variables can be graphed against each other? 2? 3? Can variables be compared against one another in a table format? What is the software #8217;s capability to create a customized template for displaying results via graphs and defining each variable on the graphs? Export Capabilities #8211; what are the solver #8217;s capabilities to export data to be graphed in another program (e.g. Excel)? To export graphs into other programs? To what programs can the data and graphs be exported? Does the user interface/graphic capability of the software allow the user to look at the model at an aggregated level, and then in more detail? For instance, say the final result shows fuel consumption for all residential consumers in the US. Would the interface/graphic capability show consumption of a particular type of fuel (e.g. natural gas, wind, or solar) for a particular state? How does the solver read in data or the math programming language? How does it deal with data that have more than 2 dimensions? Does the solver have the capability to solve linear programming, mixed integer programming, quadratic, and mixed integer quadratic programming problems? What are some of the solver #8217;s limitations and/or glitches when solving linear/mixed integer/quadratic/mixed integer quadratic programming problems? Can the solver just solve for individual components of the model, not the entire model, at any given time? Can different users use the optimizing engine to solve for different components of model simultaneously? Can you estimate the time for the optimizing engine to solve a model, based on the size of the model? Because the Energy Information Administration #8217;s (EIA) National Energy Modeling System (NEMS) is considered public information, EIA must often make the source code, input files, and optimizing engine available to outside users. How could the solver be made available through these outside users? Is there a separate licensing term for them? Can other solvers be added to the DLL or other kinds of library in which solver engines are kept? For instance, the EIA originally used a solver from KETRON. Later, it decided that the DASH optimizing engine met some of its other needs. KETRON customized its solver so that it can call DASH. Does the solver have the capability for this kind of revision? In what kinds of application programming language can the DLL or library be embedded? ICF is currently dealing with input files that contain large multidimensional arrays with few nonzero entries. How does the solver deal with sparse matrices? Would this method permit allocation of less memory to large sparse matrices? What are the solver #8217;s presolve and postsolve capabilities so as to make data more manageable? What kinds of data management tools are used in the solver for generating matrices and reports, optimization control, and solution access? How do they work with database and spreadsheet applications such as Access and Excel? How do they work with text files? Can a user view a log that reports status of the model run during the optimization process? Could the status be made available after a certain number of iterations? If so, how is this done? Jenny C. Chen Associate ICF International 9300 Lee Highway Fairfax, VA 22031 Phone: 7032182714 Fax: 7039343915
Dear GLPK Personnel: ICF came across the GLPK package via recommendations from
operations research analysts working within the Office of Integrated Analysis
and Forecasting within the Energy Information Administration (EIA). ICF
is helping the EIA conduct a survey of solvers that can serve as costeffective
alternatives to solver engines such as DASH and CPLEX. Below, I’ve
listed several questions that I have about GLPK. If you can take a moment
to answer them, I would greatly appreciate it. Thank you! Software Requirements
Calculation Requirements
Jenny
C. Chen Associate ICF
International 9300
Lee Highway Fairfax,
VA 22031 Phone:
7032182714 Fax:
7039343915 
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