Difference between revisions of "LpWriteIIS"
(Removed the constraintsOnly parameter)
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[[What's new in Analytica 4.0?]] >
 
[[What's new in Analytica 4.0?]] >
  
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= LpWriteIIS( lp ; filename ; ''constraintsOnly ; format '') =
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= LpWriteIIS( lp, filename ) =
  
 
Finds an Irreducibly Infeasile Subset (IIS) of Constraints in a linear program defined using [[LpDefine]], and writes a description of the IIS to an indicated file.  Returns the full file path to the file written.
 
Finds an Irreducibly Infeasile Subset (IIS) of Constraints in a linear program defined using [[LpDefine]], and writes a description of the IIS to an indicated file.  Returns the full file path to the file written.
  
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An Irreducibly Infeasibe Subset (IIS) of constraints is a subset of your constraints which contains no feasible solution, but which has the property that if any single constraint is removed, there will be feasible solutions.  Thus, it is a minimal set of conflicting constraints.
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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.
  
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When [[LpStatusNum]] returns 2, 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.   
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When [[LpStatusNum]] returns 5, 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.   
  
 
'''''Parameters:'''''
 
'''''Parameters:'''''
 
* '''''lp''''' : A linear program created using [[LpDefine]].
 
* '''''lp''''' : A linear program created using [[LpDefine]].
 
* '''''filename''''': A textual filename.  Relative file paths are interpreted relative to the [[CurrentDataDirectory]].
 
* '''''filename''''': A textual filename.  Relative file paths are interpreted relative to the [[CurrentDataDirectory]].
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* '''''constraintsOnly''''': (optional) If false (default), then both constraints and variable bounds are relaxed to obtain the IIS.  Removing any single variable bound, or any single constraint, in the resulting problem would then result in a feasible solution.  If constraintsOnly is specified as true, then variable bounds are not adjusted.
 
 
* '''''format''''': (optional) Specifies the file format.  Possible values are:   
 
* '''''format''''': (optional) Specifies the file format.  Possible values are:   
 
** "LP" (or 1)
 
** "LP" (or 1)

Revision as of 22:49, 9 April 2007


What's new in Analytica 4.0? >

LpWriteIIS( lp, filename )

Finds an Irreducibly Infeasile Subset (IIS) of Constraints in a linear program defined using LpDefine, 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 LpStatusNum returns 5, 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.

Parameters:

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

See Also

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