APMonitor Documentation

APMonitor, or "Advanced Process Monitor" is optimization software for mixed-integer and differential algebraic equations. It is coupled with large-scale solvers for linear, quadratic, nonlinear, and mixed integer programming (LP, QP, NLP, MILP, MINLP). Modes of operation include data reconciliation, moving horizon estimation, real-time optimization, dynamic simulation, and nonlinear predictive control with solution capabilities for high-index differential and algebraic (DAE) equations. It is available as a MATLAB toolbox, a Python module, a Julia package, or from a web browser interface.

Reference to Cite

Please consider citing the following article for the APMonitor Optimization Suite.

  • Hedengren, J. D. and Asgharzadeh Shishavan, R., Powell, K.M., and Edgar, T.F., Nonlinear Modeling, Estimation and Predictive Control in APMonitor, Computers and Chemical Engineering, Volume 70, pg. 133–148, 2014, DOI: 10.1016/j.compchemeng.2014.04.013. Article - Preprint - BibTeX - RIS

Other applications of APMonitor are listed on the references page. Please send a note to if you'd like to add a reference to the list.

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Differential and Algebraic Equations

Differential and algebraic (DAE) models are a natural expression of systems that change with time. These dynamic systems may be as simple as a falling apple or as complex as biological metabolic pathways. DAE models are generally easy to write but often difficult to solve analytically. Entire university level courses are devoted to the solution of particular types of differential equations in analytic form. Solution of more complex systems is better handled through numeric approaches. There are many software packages that can solve DAE models for small and medium size problems. APMonitor is designed to solve large-scale problems. Additionally, other software packages often require the user to reformulate the equations into a restrictive form. APMonitor allows an open-equation format that is less restrictive.

Solution options

APMonitor uses a simultaneous solution approach to solve the differential equations. The differential equations are converted to algebraic equations and solved with large-scale sparse solvers. There are an assortment of solvers available with various user's licenses, ranging from free and open-source to commercial.

Range of usage

APMonitor is advanced process control and optimization software for industrial-scale systems. The software interfaces to live systems to provide advanced diagnostics, meet safety and environmental constraints, and drive the process to economic optimum. With rapidly changing feedstock and commodity pricing, this application enables instant and continual realignment to real operating objectives. These may include:

  • Meet regulatory reporting requirements
  • Flow assurance of oil and gas transport pipelines
  • Visualize data from remote locations
  • Reduce alarms by consolidating relevant information
  • Provide soft sensing
  • Automatic control of continuous and batch systems
  • Increase production 3-5% without equipment changes

A number of prebuilt asset models are available with the APMonitor software. The chemical processing modeling package includes reactors, distillation columns, and compressors necessary for industrial scale processes. A modeling language interface to MATLAB and Python extends the applicability for pre- and post-processing of the optimization solution results.