Filename extension | .nl |
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Developed by |
Robert Fourer David Gay Brian Kernighan Bell Labs |
Type of format | mathematical programming |
nl is a file format for presenting and archiving mathematical programming problems. Initially this format has been invented for connecting solvers to AMPL. 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. Many solvers such as CPLEX, Gurobi and MOSEK accept this format either directly or through special driver programs.
The open-source AMPL Solver Library (ASL) distributed via Netlib and AMPL/MP library provide nl parsers that are used in many solvers.