Editing AMPL (section)

==Features==
AMPL features a mix of [[declarative programming|declarative]] and [[imperative programming|imperative]] programming styles. Formulating optimization models occurs via declarative language elements such as sets, scalar and multidimensional parameters, decision variables, objectives and [[constraint (mathematics)|constraints]], which allow for concise description of most problems in the domain of mathematical optimization.

Procedures and [[control flow]] statements are available in AMPL for
* the exchange of data with external data sources such as [[spreadsheet]]s, [[database]]s, [[XML]] and text files
* data pre- and post-processing tasks around optimization models
* the construction of hybrid algorithms for problem types for which no direct efficient solvers are available.

To support re-use and simplify construction of large-scale optimization problems, AMPL allows separation of model and data.

AMPL supports a wide range of problem types, among them:
* [[Linear programming]]
* [[Quadratic programming]]
* [[Nonlinear programming]]
* [[Linear programming#Integer unknowns|Mixed-integer programming]]
* Mixed-integer quadratic programming with or without [[Convex function|convex]] quadratic constraints
* Mixed-integer nonlinear programming
* [[Second-order cone programming]]
* [[Global optimization]]
* [[Semidefinite programming]] problems with [[Bilinear form|bilinear]] matrix inequalities
* [[Complementarity theory]] problems (MPECs) in discrete or continuous variables
* [[Constraint programming]]<ref name="cp-support">
{{Cite journal
  |author-link = Robert Fourer
  | title = Extending an Algebraic Modeling Language to Support Constraint Programming
  | journal = INFORMS Journal on Computing
  | volume = 14
  | issue = 4
  | pages = 322–344
  | year = 2002
  | url = http://joc.journal.informs.org/content/14/4/322
  | doi=10.1287/ijoc.14.4.322.2825| last1 = Fourer
  | first1 = Robert
  | last2 = Gay
  | first2 = David M.
  | citeseerx = 10.1.1.8.9699
  }}
</ref>

AMPL invokes a solver in a separate process which has these advantages:
* User can interrupt the solution process at any time
* Solver errors do not affect the interpreter
* 32-bit version of AMPL can be used with a 64-bit solver and vice versa
Interaction with the solver is done through a well-defined [[nl (format)|nl interface]].