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Yet Another Math Programming Consultant
16  mai     15h24
Ranking using numpy.argsort
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04  mai     20h21
Evil Sudoku
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01  mai     17h48
Getting rid of non-linearities
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28  avril     10h32
Inverting a large, dense matrix
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16  avril     22h03
Expanding Visual Studio in the Task Manager
   nbsp This is scary Note that is in an idle state nothing compiling running or debugging at the moment Soon we all need GB of RAM
14  avril     06h41
GAMS: Undocumented PUT formats
   The GAMS documentation mentions f nr standard notation and f nr scientific notation for formatting numeric items using the PUT statement There are however a few more Here we print values using different formats f nr f nr f nr f nr
10  avril     23h20
Rewriting old GAMS code
   It is always a good idea to revisit existing GAMS code and see if we can improve it Here is an example of an actual model The problem is that we want to set up a mapping set between two sets based on the first two characters If they are the same the pair should be added to the mapping The old
05  mars     07h29
Bostock’s command-line cartography tutorial under Windows
   In an excellent tutorial is presented about the process of making maps It is a little bit dated so here I develop some Windows based scripts that make it possible to follow these tutorials The goal is two fold Make things work for Windows I am comfortable with the Unix command line but
18  février     16h06
Wanted: better error messages
   In a user tries the following constraint mdl addConstrs t i k X i j k te i lt gt gt z i k for i j k in arcos if i and i t and X and variables This is not accepted and the following error message is issued AttributeError gurobipy QuadExpr object has
16  février     13h00
SLSQP original paper
   This is somewhat hard to find although I did so I share it This is the original paper describing the SLSQP solver used in scipy To download use the menu button at the bottom and choose Download a Copy ReferencesKraft D A software package for sequential
15  février     15h29
Visualization: Animating flow along an edge
   In a large network it is a bit of a pain to visualize the flow Here is an attempt to show the shortest path in a random sparse directed graph The shortest path is of course a min cost flow of one unit I used cytoscape js to generate the picture A colleague asked the question of whether we
10  février     15h48
4-color maps: another model
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31  janvier     11h26
Is a heuristic a solver?
   Can we call a heuristic especially a meta heuristic a solver I am not so sure Warning this is somewhat of an opinionated rant Many of you may not agree The name solver seems to imply that the underlying algorithm knows when an optimization problem is solved By that I mean it can stop at
25  janvier     16h51
A different coloring problem
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24  janvier     01h02
Coloring the US county map
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19  janvier     12h10
An All-Paths Network Problem
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28  décembre     07h37
Importing JSON files into GAMS
   JSON JavaScript Object Notation files provide a flexible and simple way to store and exchange data It is text so we can easily look at it JSON files typically have the extension json using it may help syntax coloring in editors JSON can represent rather complex tree like data
26  décembre     07h30
MacMahon Squares
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18  novembre     11h30
Solve status: not as easy as it looks
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07  novembre     18h41
Shortest path in GAMS
   Here is a presentation for a GAMS workshop We focus on the Shortest Path LP problem I use this model to discuss a lot of different things Modeling networks in GAMSSparse data structures in GAMSRandom number generationPython and GAMSPut facilityVisualization Python and HTML Javascript based
01  novembre     17h17
Transportation Model (sharing a PowerPoint presentation)
   trnsport gms is the first model in the GAMS model library Here I am using it to give an introduction in GAMS The PowerPoint presentation has three major sections the historical importance of the transportation model in economics Nobel prizes have been earned a quick introduction to the GAMS
21  octobre     14h05
A multi-objective nonlinear integer programming problem
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16  octobre     14h24
Stacking 3d boxes under rotation
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12  octobre     02h59
2d knapsack problem
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28  septembre     15h22
Another Rook Tour on the Chessboard
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