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CPLEX
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<h2 id="history">History</h2> <p>The CPLEX Optimizer was named after the <a href="/facts/Simplex_method/9fndF6cq">simplex method</a> implemented in the <a href="/facts/C_programming_language/Ky2No763">C programming language</a>. However, today it also supports other types of <a href="/facts/Mathematical_optimization/oRn8Iv5I">mathematical optimization</a> and offers interfaces other than C. It was originally developed by <a href="/facts/Robert_E._Bixby/KoC9ynSL">Robert E. Bixby</a> and sold commercially in 1988 by CPLEX Optimization Inc. This was acquired by <a href="/facts/ILOG/smnFvLJz">ILOG</a> in 1997 and ILOG was subsequently acquired by <a href="/facts/IBM/QszA7nwd">IBM</a> in January 2009.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> CPLEX continues to be actively developed by IBM. </p> <h2 id="features">Features</h2> <p>The IBM ILOG CPLEX Optimizer solves <a href="/facts/Integer_programming/MDaaadoA">integer programming</a> problems, very large<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> <a href="/facts/Linear_programming/GduXFQxT">linear programming</a> problems using either primal or dual variants of the <a href="/facts/Simplex_method/9fndF6cq">simplex method</a> or the barrier <a href="/facts/Interior_point_method/prIIrceN">interior point method</a>, convex and non-convex <a href="/facts/Quadratic_programming/ct4RIUgs">quadratic programming</a> problems, and convex quadratically constrained problems (solved via <a href="/facts/Second-order_cone_programming/TNXLKvK7">second-order cone programming</a>, or SOCP). </p><p>The CPLEX Optimizer has a modeling layer called Concert that provides interfaces to the <a href="/facts/C%2B%2B/Et0F2qn9">C++</a>, <a href="/facts/C_Sharp_(programming_language)/UC2gxeyb">C#</a>, and <a href="/facts/Java_programming_language/9ScgFyAL">Java</a> languages. There is a <a href="/facts/Python_programming_language/YbuGqofa">Python</a> language interface based on the C interface. Finally, a stand-alone Interactive Optimizer executable is provided for debugging and other purposes. </p><p>The CPLEX Optimizer is accessible through independent modeling systems such as <a href="/facts/AIMMS/YLM2jY9Y">AIMMS</a>, <a href="/facts/AMPL/pzceW9mH">AMPL</a>, <a href="/facts/General_Algebraic_Modeling_System/lSMIxcdm">GAMS</a>, <a href="/facts/OptimJ/5SvHdf3W">OptimJ</a> and <a href="/facts/TOMLAB/YtuEVte9">TOMLAB</a>. In addition to that AMPL provides an interface to the CPLEX CP Optimizer. </p><p>The full IBM ILOG CPLEX Optimization Studio consists of the CPLEX Optimizer for mathematical programming, the CP Optimizer for constraint programming,<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> the <a href="/facts/Optimization_Programming_Language/P01WmLXo">Optimization Programming Language</a> (OPL), and a tightly integrated IDE. </p> <h2 id="release-history">Release history</h2> <p>Prior to IBM acquiring ILOG, the CPLEX team published a release history of CPLEX.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> <table><tbody><tr><th>Version</th><th>Release Date</th><th>Key Features</th></tr><tr><td>22.1.1</td><td>December, 2022</td><td>Python 3.7 support dropped, new solver parameter added.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a></td></tr><tr><td>22.1.0</td><td>March, 2022</td><td>Python 3.9 and 3.10 support added, new solver parameters added.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></td></tr><tr><td>20.1</td><td>December, 2020</td><td>MIP performance improvements, new 'emphasis MIP 5' mode, etc.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></td></tr><tr><td>12.10</td><td>December, 2019</td><td>MIP performance improvements and the addition of a generic branching callback to the other generic callbacks introduced in version 12.8.</td></tr><tr><td>12.9</td><td>March, 2019</td><td>Direct support for multiobjective optimization, callback functionality improvement.</td></tr><tr><td>12.8</td><td>December, 2017</td><td>Generic callback, API recorder to facilitate debugging, subMIP control parameters, Download and Go offering.</td></tr><tr><td>12.7</td><td>November, 2016</td><td>Automated Benders decomposition, modeling assistance tool, runseeds command to better assess performance variability.</td></tr><tr><td>12.6.2</td><td>June, 2015</td><td>Performance improvements (mainly for SOCP, MISOCP, non-convex QP), support for cloud based optimization.</td></tr><tr><td>12.6</td><td>December, 2013</td><td>Support for nonconvex QPs and MIQPs, distributed parallel MIP and more parallelism at the root node for MIPs..</td></tr><tr><td>12.5</td><td>October, 2012</td><td>MIP performance improvements, random seed parameter to address performance variability, remote object, duals for QCPs, deterministic tuning tool.</td></tr><tr><td>12.4</td><td>November, 2011</td><td>Deterministic time limit support, duals for SOCPs, quadratic expression API in Concert, performance improvements across all algorithms, but especially MIP.</td></tr><tr><td>12.3</td><td>June, 2011</td><td>Support for large nonzero counts that require 64 bit indexing, local optima for non-convex QP, and globalization.</td></tr><tr><td>12.2</td><td>June, 2010</td><td>More parallelism at the root node, deterministic parallel concurrent LP optimization, along with some additional barrier performance improvements and additional tools for diagnosing ill conditioned basis matrices in MIPs.</td></tr><tr><td>12.0</td><td>April, 2009</td><td>The first version after IBM acquired ILOG. Includes connectors for Python, MATLAB and Excel. Deterministic parallel barrier is also included.</td></tr><tr><td>11.0</td><td>October, 2007</td><td>Breakthrough performance gains for mixed integer programming (MIP) models and enhanced parallel MIP optimization. The MIP solution pool feature and the performance tuning utility are introduced.</td></tr><tr><td>10.0</td><td>January, 2006</td><td>Performance improvements in the primal simplex and barrier methods, as well as the MIP optimizer. Indicator constraints and solution polishing heuristics are introduced and improvements to infeasibility analysis are made.</td></tr><tr><td>9.0</td><td>December, 2003</td><td>Performance improvements in primal and dual simplex methods and the MIP optimizer. It includes ILOG Concert Technology for .NET users and support for quadratically constrained programs.</td></tr><tr><td>8.0</td><td>July, 2002</td><td>MIP performance improvements and support for mixed integer quadratic programs.</td></tr><tr><td>7.5</td><td>December, 2001</td><td>ILOG Concert Technology for Java users.</td></tr><tr><td>7.0</td><td>October, 2000</td><td>ILOG Concert Technology for C++ users.</td></tr><tr><td>6.5</td><td>March, 1999</td><td>Significant performance improvements in primal and dual simplex methods, and ILOG CPLEX Mixed Integer Optimizer.</td></tr><tr><td>6.0</td><td>April, 1998</td><td>Significant performance improvements in primal and dual simplex methods, and CPLEX Barrier Optimizer.</td></tr><tr><td>5.0</td><td>September, 1997</td><td>New memory model for easy C++ integration.</td></tr><tr><td>4.0.5</td><td>March, 1996</td><td>Parallel CPLEX Mixed Integer Solver is introduced.</td></tr><tr><td>4.0</td><td>December, 1995</td><td>Redesigned advanced programming interface (API) to allow thread-safe applications.</td></tr><tr><td>3.0.8</td><td>March, 1995</td><td>Parallel CPLEX Barrier Solver is introduced.</td></tr><tr><td>3.0</td><td>April, 1994</td><td>CPLEX Barrier Solver is introduced.</td></tr><tr><td>2.1</td><td>March, 1993</td><td>Introduction of CPLEX Presolve algorithms.</td></tr><tr><td>2.0</td><td>April, 1992</td><td>Performance improvements.</td></tr><tr><td>1.2</td><td>1991</td><td>Support for the dual simplex method and CPLEX Mixed Integer Optimizer.</td></tr><tr><td>1.0</td><td>1988</td><td>Primal Simplex Method</td></tr></tbody></table> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/FICO_Xpress/mEFKqwEG">FICO Xpress</a></li> <li><a href="/facts/GLPK/9j7hhN95">GLPK</a></li> <li><a href="/facts/Gurobi_Optimizer/H0arxhjT">Gurobi Optimizer</a></li> <li><a href="/facts/SCIP_(optimization_software)/3ovWAS4b">SCIP</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="http://www.ibm.com/analytics/cplex-optimizer">IBM ILOG CPLEX Optimizer home page</a></li> <li><a href="http://www.ibm.com/analytics/cplex-cp-optimizer">IBM ILOG CPLEX CP Optimizer home page</a></li> <li><a href="http://www.ibm.com/products/ilog-cplex-optimization-studio/">Optimization Programming Language (OPL)</a></li> <li><a href="http://www.ibm.com/software/websphere/products/optimization/cplex-studio-preview-edition/">Free preview edition of IBM ILOG CPLEX Optimization Studio</a></li> <li><a href="http://ibm.biz/COS_Forums">IBM ILOG Optimization Forums</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>IBM Completes Acquisition of ILOG, 6 Jan 2009, archived from the original on January 22, 2009, retrieved 24 June 2020 <a href="https://web.archive.org/web/20090122054110/http://www-03.ibm.com/press/us/en/pressrelease/26403.wss" target="_blank">https://web.archive.org/web/20090122054110/http://www-03.ibm.com/press/us/en/pressrelease/26403.wss</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Mittelmann, H. D. (10 July 2007), "Recent Benchmarks of Optimization Software", 22nd European Conference on Operational Research, EURO XXII Prague, Czech Republic: Dept of Math and Stats Arizona State University <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Laborie P, Rogerie J, Shaw P, Vilim P (2018). "IBM ILOG CP optimizer for scheduling". Constraints. 23 (2): 210–250. doi:10.1007/s10601-018-9281-x. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"CPLEX History". CPLEX History as published by ILOG. Archived from the original on 13 April 2009. Retrieved 24 June 2020. <a href="https://web.archive.org/web/20090413054926/http://www.ilog.com/products/cplex/news/history.cfm" target="_blank">https://web.archive.org/web/20090413054926/http://www.ilog.com/products/cplex/news/history.cfm</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"Release notes for CPLEX 22.1.1". Archived from the original on 11 January 2023. Retrieved 11 January 2023. <a href="https://www.ibm.com/docs/en/icos/22.1.1?topic=2211-release-notes-cplex" target="_blank">https://www.ibm.com/docs/en/icos/22.1.1?topic=2211-release-notes-cplex</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"Release notes for CPLEX 22.1.0". Retrieved 11 January 2023. <a href="https://www.ibm.com/docs/en/icos/22.1.0?topic=2210-release-notes-cplex" target="_blank">https://www.ibm.com/docs/en/icos/22.1.0?topic=2210-release-notes-cplex</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>"CPLEX 20.1 Release Notes". Retrieved 4 March 2021. <a href="https://www.ibm.com/support/knowledgecenter/SSSA5P_20.1.0/ilog.odms.studio.help/CPLEX/ReleaseNotes/topics/releasenotes201/home.html" target="_blank">https://www.ibm.com/support/knowledgecenter/SSSA5P_20.1.0/ilog.odms.studio.help/CPLEX/ReleaseNotes/topics/releasenotes201/home.html</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> </ol>