GAMS


  • Looking for infeasibilities in Gams

    A good CGE modelers always checks the calibration of a CGE model using a simple trick: If you set the iteration limit of the model to zero and you try to solve the model, GAMS should find a solution if you correctly initialized and wrote down your model equations with the use of the benchmark data. Often, the calibration is not done properly and this can be seen (using the iteration set to zero) by looking at the infeasibilities of the equations and the variables.

    If you use MPSGE to write down your model, the infeasibilities are easily interpreted. If … Read the rest “Looking for infeasibilities in Gams”

  • Generating headings for project files

    I use the free software AutoHotkey (AHK) for automation of many things. One of those things is generating headings for my project file. I developed a simple AHK-script that asks me for the project name, the topic and then inserts the heading with additional information like my name, my E-mail address and a keyword for subversion.

    The script is quite simple and I have adopted it for headings for several project files (tex, R and gams). The only difference being the characters used to comment out a line.

    Here is the script

    Read the rest “Generating headings for project files”

  • Automatic operator formatting mode in Emacs

    Emacs has a nice new mode called electric-operator developed by David Spepherd. It helps when you write code by formatting all operators in a predefined way. For example, in R it adds spaces around the operator signs, when you write 1+1, this is automatically converted into 1 + 1.

    You can define your own way of formatting for other modes. For gams-mode you add the following to your .emacs file

    Read the rest “Automatic operator formatting mode in Emacs”

  • Using file templates in Emacs

    A good practice in modeling is to place information related to the project your are working on, the subject, the data and your personal information like E-mail address at the top of your file. In Emacs you can define skeleton functions that will prompt for the information and put it in the file. Below is an example for a file with as comment symbol “**: (the $Id: $ is for my version control system, that automatically will add the information on the last commit in this line).

    image

    Below you see how to make a function using skeleton. As I don’t … Read the rest “Using file templates in Emacs”

  • Automating writing LaTeX papers even further

    In an earlier post I wrote on how to use R to produce all kind of figures and tables for a LaTeX paper. This time, I will show, how to automate this process even more.

    My work flow consists of a batch file, that runs my model, sends the results to R, produces my tables and figures and sends these to my paper: If I change my model, I just have to run this batch file, and the results in my paper are automatically adjusted. One smaller problem is that I often write in my text on a specific value … Read the rest “Automating writing LaTeX papers even further”


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