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dylp Overview

dylp is an implementation of the dynamic simplex algorithm. Briefly, dynamic simplex attempts to work with an active constraint system which is a subset of the full constraint system. It alternates between primal and dual simplex phases. Between simplex phases, it deactivates variables and constraints which are not currently useful, and scans the full constraint system to activate variables and constraints which have become useful. The dylp documentation describes dylp's algorithms in detail.

dylp is intended as a development code. The implementation puts more weight on clarity than efficiency and is heavily instrumented and commented. It can be built with extensive statistics, informational printing, and consistency checks. It can also be built without any of these. Fully optimised, it's decently fast, with run times averaging three to four times that of clp, depending on the problem and the runtime environment.

dylp is a C code, and can be used in a pure C environment completely independent of other COIN software. It also has a COIN-OR OSI interface, OsiDylp, which takes advantage of capabilities provided by COIN (e.g., enhanced input/output and constraint system preprocessing) and is recommended if you're working in a C++ environment.

dylp is not under active development and languished for many years following the author's retirement. Recently it's been upgraded to conform to the COIN GitHub repository standards.

Download, Configuration, and Testing

dylp has lain dormant for a long time and has no current releases. Clone the git repository and use the master branch. You can use coinbrew to automate the process of cloning the repositories for dylp and its dependencies and building the software. This is the best way to get started. If you want to build in a separate directory from the source files, use the coinbrew option --build-dir. If you want to install in a specified directory, use the coinbrew option --prefix.

Once you have created the necessary repositories, the minimal action required for configuration and build is to run the commands


in the top level directory of the distribution. Run

./configure --help

for a list of available configuration options. If you're building in a directory separate from the source directory, run configure and make from the build directory as

cd /path/to/build/Dylp

To install in a specified directory, use the --prefix option to configure as

path/to/src/Dylp/configure --prefix /path/to/install
make install

For a test of correct installation, dylp runs its own unit test and the OsiDylp unit test. Simply type the command

make test

in the top level build directory to build and run the unit tests.


The dylp distribution also provides two simple main programs in the directory DyLP/examples. Be sure to execute the command

make install

in the top level build directory before attempting to build the examples! To build the examples, change directory to DyLP/examples and execute the command

make examples

A simple shell script, plain, provides a convenient wrapper for both main programs. Execute the command 'plain --help' for usage information.


Appropriate versions of dylp's dependencies are specified in the config.yml used by coinbrew.


There are undoubtably a few left somewhere. If you run across one, please let us know. The preferred way is to use a issue. You can browse existing issues to see if your bug has already been reported and add additional information. Otherwise, please submit a new issue.

Project Manager

@LouHafer: Lou Hafer (retired)


Dynamic Simplex solver







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