nl (format)

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Nl (format)
Filename extension
Developed byRobert Fourer
David Gay
Brian Kernighan
Bell Labs
Type of formatmathematical programming

nl is a file format for presenting and archiving mathematical programming problems.[1] Initially this format has been invented for connecting solvers to AMPL.[2] It has also been adopted by other systems such as COIN-OR (as one of the input formats), FortSP (for interacting with external solvers), and Coopr (as one of its output formats).

The nl format supports a wide range of problem types, among them:

The nl format is low-level and is designed for compactness, not for readability. It has both binary and textual representation. Most commercial and academic solvers accept this format either directly or through special driver programs.

The open-source AMPL Solver Library (ASL) distributed via Netlib[4] and AMPL/MP library [5] provide nl parsers that are used in many solvers.

See also[edit]

  • sol (format) - a file format for presenting solutions of mathematical programming problems


  1. ^ David Gay (2005). Writing .nl Files (PDF) (Technical report). Albuquerque, NM: Sandia National Laboratories. CiteSeerX
  2. ^ David Gay (1993). Hooking Your Solver to AMPL (PDF) (Technical report). Murray Hill, NJ: Bell Laboratories. 97-4-06.
  3. ^ Robert Fourer; David M. Gay (2002). "Extending an Algebraic Modeling Language to Support Constraint Programming". INFORMS Journal on Computing. 14 (4): 322–344. CiteSeerX doi:10.1287/ijoc.14.4.322.2825.
  4. ^
  5. ^