OptWriteIIS(opt, filename, format )

Finds an Irreducibly Infeasile Subset (IIS) of Constraints in a linear program defined using DefineOptimization, and writes a description of the IIS to an indicated file. Returns the full file path to the file written.

An Irreducibly Infeasibe Subset (IIS) of constraints is a subset of your constraints (and variable bounds) which contains no feasible solution, but which has the property that if any single constraint or variable bound is removed, there will be feasible solutions. Thus, it is a minimal set of conflicting constraints.

When OptStatusNum(opt, true) returns 0, it indicates that there are no feasible solutions -- that the set of constraints are contradictory. This function is useful for locating the source of the contradiction.


  • «opt» : A linear program created using DefineOptimization.
  • «filename»: A textual filename. Relative file paths are interpreted relative to the CurrentDataFolder.
  • «format»: (optional) Specifies the file format. Possible values are:
    "LP" (or 1)
    "MPS" (or 2)
    "LPFML" (or 3)


This function was introduced in Analytica 4.3 to replace the previous version LpWriteIIS.

See Also


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