Yet Another Math Programming Consultant

I am a full-time consultant and provide services related to the design, implementation and deployment of mathematical programming, optimization and data-science applications. I also teach courses and workshops. Usually I cannot blog about projects I am doing, but there are many technical notes I'd like to share. Not in the least so I have an easy way to search and find them again myself. You can reach me at erwin@amsterdamoptimization.com.

Friday, October 31, 2008

Gdxls: call only if needed

›
Here is a trick to call gdxls from GAMS only if the source file input.xls is newer than the destination file input.gdx: $call test input.xls...
Thursday, October 30, 2008

Lp2gams update

›
Added semi-continuous variables so we can translate lp-solve models with such variables. See: http://yetanothermathprogrammingconsultant.blo...

GAMS obscure error message

›
When we read using GAMS 22.7 a GAMS restart file produced by GAMS 22.8 we get a nasty error message. Looks like the versioning mechanism on ...

GAMS Function and Derivative Evaluation

›
I have two different formulations of a linearly constrained NLP (i.e. the objective is nonlinear). The difference is how we formulate the ob...

Langford's problem

›
The problem is to find integer sequences with special characteristics. See http://www.lclark.edu/~miller/langford.html . An example of a seq...
Tuesday, October 28, 2008

Grooml modeling language

›
This looks interesting for linear models: http://combean.sourceforge.net/ http://combean.sourceforge.net/groomlINFORMS2008.pdf http://combea...
Monday, October 27, 2008

gdxls: write xls files on Linux

›
The gdxls tool is a Java based alternative for GDXXRW on Linux and other non-Windows operating systems. Besides converting xls→gdx (as descr...
Saturday, October 25, 2008

gdxls: read xls files on Linux

›
The GAMS tool GDXXRW is not available under Linux, Unix and OS X.  As I needed to have this functionality in some projects, I developed a Ja...
6 comments:
Thursday, October 23, 2008

Magic squares in GAMS

›
In  http://yetanothermathprogrammingconsultant.blogspot.com/2008/10/magic-squares-with-ms-csp-solver.html  we describe a CSP formulation usi...
1 comment:

Reading Excel XLS files on Linux

›
Using the code from  http://poi.apache.org/  I can now read and process Excel XLS files on Linux (and Mac).  Note: this code implements the ...
‹
›
Home
View web version

About Me

Erwin Kalvelagen
View my complete profile
Powered by Blogger.