simplex_lpsolve.c File Reference

Implementation of the functions operating on TSimplex using the Lp_solve backend. More...

#include "simplex.h"
#include "error.h"
#include "geom.h"
#include "defines.h"
#include <math.h>
#include <string.h>

Go to the source code of this file.

Functions
void	SimplexCreate (double epsilon, unsigned int ncols, TSimplex *s)
	Constructor.
void	ResetSimplex (TSimplex *s)
	Resets the simplex structure.
unsigned int	SimplexNColumns (TSimplex *s)
	Gets the number of columns (i.e., variables) of the simplex structure.
unsigned int	SimplexNRows (TSimplex *s)
	Gets the number of rows (i.e., constraints) of the simplex structure.
void	SimplexSetColBounds (unsigned int ncol, Tinterval i, TSimplex s)
	Sets the bounds for a given column (i.e., variable).
void	SimplexGetColBounds (unsigned int ncol, Tinterval i, TSimplex s)
	Gets the bounds for a given column (i.e., variable).
void	SimplexGetColConstraint (unsigned int ncol, TLinearConstraint lc, TSimplex s)
	Gets a column from the simplex in the form of a linear constraint.
boolean	SimplexColEmpty (unsigned int ncol, TSimplex *s)
	Checks if a simplex column is empty.
double	SimplexGetColPrimal (unsigned int ncol, TSimplex *s)
	Gets a column primal value after solving the simplex.
double	SimplexGetColDual (unsigned int ncol, TSimplex *s)
	Gets a column dual value after solving the simplex.
void	SimplexSetRowBounds (unsigned int nrow, Tinterval i, TSimplex s)
	Sets the bounds for a given row (i.e., constraint).
void	SimplexGetRowBounds (unsigned int nrow, Tinterval i, TSimplex s)
	Gets the bounds for a given row (i.e., constraint).
void	SimplexGetRowConstraint (unsigned int nrow, TLinearConstraint lc, TSimplex s)
	Gets a row constraint from the simplex.
double	SimplexGetRowPrimal (unsigned int nrow, TSimplex *s)
	Gets a row primal value after solving the simplex.
double	SimplexGetRowDual (unsigned int nrow, TSimplex *s)
	Gets a row dual value after solving the simplex.
void	SimplexAddNewConstraintRaw (TLinearConstraint lc, TSimplex s)
	Adds a row (i.e., a constraint) to the simplex.
void	SimplexSetOptimizationFunction (TLinearConstraint obj, TSimplex s)
	Sets a new objective function.
void	SimplexGetOptimizationFunction (TLinearConstraint obj, TSimplex s)
	Gets a current objective function.
double	SimplexGetOptimalValueRaw (TSimplex *s)
	Gets the optimal value after optimizing the problem.
unsigned int	SimplexSolve (TSimplex *s)
	Determines an optimal value.
void	SimplexDelete (TSimplex *s)
	Destructor.

Detailed Description

Implementation of the functions operating on TSimplex using the Lp_solve backend.

See also:: TSimplex, simplex.h, simplex_clp.c, simplex_glpk.c.

Definition in file simplex_lpsolve.c.

Function Documentation

void SimplexCreate	(	double	epsilon,
		unsigned int	ncols,
		TSimplex *	s
	)

Creates a simplex structure with a given number of columns (i.e., variables) but with no rows (i.e., constraints).

Parameters:

	epsilon	Threshold to decide if a value is too small to be added to the tableau. It is also used to set up internal simplex parameters.
	ncols	Number of columns for the tableau.
	s	The simplex structure.

Definition at line 23 of file simplex_lpsolve.c.

References Error(), TSimplex::inf, TSimplex::lp, and SIMPLEX_TIMEOUT.

Referenced by ReduceBox().

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void ResetSimplex ( TSimplex * s )

Removes the rows (i.e., constraints) from the simplex structure.

Parameters:

s

The simplex structure.

Definition at line 67 of file simplex_lpsolve.c.

References TSimplex::lp.

Referenced by ReduceBox(), and ReduceRange().

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unsigned int SimplexNColumns ( TSimplex * s )

Gets the number of columns (i.e., variables) of the simplex structure.

Parameters:

s

The simplex structure.

Returns:: The number of columns (i.e., variables) of the simplex structure.

Definition at line 72 of file simplex_lpsolve.c.

References TSimplex::lp.

Referenced by SimplexGetOptimalValue(), SimplexGetOptimizationFunction(), SimplexGetRowConstraint(), and SimplexSetOptimizationFunction().

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unsigned int SimplexNRows ( TSimplex * s )

Gets the number of rows (i.e., constraints) of the simplex structure.

Parameters:

s

The simplex structure.

Returns:: The number of rows (i.e., constraints) of the simplex structure.

Definition at line 77 of file simplex_lpsolve.c.

References TSimplex::lp.

Referenced by ReduceBox(), SimplexAddNewConstraintRaw(), SimplexColEmpty(), SimplexDelete(), SimplexGetColConstraint(), SimplexGetColDual(), SimplexGetColPrimal(), SimplexGetOptimalValue(), SimplexGetOptimizationFunction(), and SimplexGetRowConstraint().

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void SimplexSetColBounds	(	unsigned int	ncol,
		Tinterval *	i,
		TSimplex *	s
	)

Sets the bounds for a given column (i.e., variable).

Parameters:

	ncol	The column whose range we have to update.
	i	The new range for the column.
	s	The simplex structure.

Definition at line 83 of file simplex_lpsolve.c.

References TSimplex::inf, INF, LowerLimit(), TSimplex::lp, and UpperLimit().

Referenced by SetSimplexBounds().

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void SimplexGetColBounds	(	unsigned int	ncol,
		Tinterval *	i,
		TSimplex *	s
	)

Gets the bounds for a given column (i.e., variable).

Parameters:

	ncol	The column whose range we have to update.
	i	The output range with the column bounds.
	s	The simplex structure.

Definition at line 103 of file simplex_lpsolve.c.

References INF, TSimplex::inf, TSimplex::lp, and NewInterval().

Referenced by SimplexGetColConstraint().

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void SimplexGetColConstraint	(	unsigned int	ncol,
		TLinearConstraint *	lc,
		TSimplex *	s
	)

Gets a column from the simplex in the form of a linear constraint.

Parameters:

	ncol	The column whose constraint we want to get.
	lc	The output linear constraint.
	s	The simplex structure.

Definition at line 121 of file simplex_lpsolve.c.

References AddTerm2LinearConstraint(), InitLinearConstraint(), TSimplex::lp, NEW, SetLinearConstraintError(), SimplexGetColBounds(), and SimplexNRows().

Referenced by SimplexGetOptimalValue().

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boolean SimplexColEmpty	(	unsigned int	ncol,
		TSimplex *	s
	)

Gets a column constraint from the simplex.

Parameters:

	ncol	The column whose constraint we want to get.
	s	The simplex structure.

Returns:: TRUE if the simplex column is empty.

Definition at line 146 of file simplex_lpsolve.c.

References TSimplex::lp, NEW, and SimplexNRows().

Referenced by ReduceBox().

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double SimplexGetColPrimal	(	unsigned int	ncol,
		TSimplex *	s
	)

Gets a column primal value after solving the simplex.

Parameters:

	ncol	The column whose primal value we need.
	s	The simplex structure.

Returns:: The primal value for the column.

Definition at line 166 of file simplex_lpsolve.c.

References TSimplex::lp, and SimplexNRows().

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double SimplexGetColDual	(	unsigned int	ncol,
		TSimplex *	s
	)

Gets a column dual value after solving the simplex.

Parameters:

	ncol	The column whose dual value we need.
	s	The simplex structure.

Returns:: The primal value for the column.

Definition at line 171 of file simplex_lpsolve.c.

References TSimplex::lp, and SimplexNRows().

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void SimplexSetRowBounds	(	unsigned int	nrow,
		Tinterval *	i,
		TSimplex *	s
	)

Sets the bounds for a given row (i.e., constraint).

Parameters:

	nrow	The column whose range we have to update.
	i	The new range for the row.
	s	The simplex structure.

Definition at line 177 of file simplex_lpsolve.c.

References TSimplex::inf, INF, IntervalSize(), LowerLimit(), TSimplex::lp, and UpperLimit().

Referenced by SimplexAddNewConstraintRaw().

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void SimplexGetRowBounds	(	unsigned int	nrow,
		Tinterval *	i,
		TSimplex *	s
	)

Gets the bounds for a given row (i.e., constraint).

Parameters:

	nrow	The column whose range we have to update.
	i	The output range with the column bounds.
	s	The simplex structure.

Definition at line 229 of file simplex_lpsolve.c.

References INF, TSimplex::inf, TSimplex::lp, and NewInterval().

Referenced by SimplexGetOptimalValue(), and SimplexGetRowConstraint().

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void SimplexGetRowConstraint	(	unsigned int	nrow,
		TLinearConstraint *	lc,
		TSimplex *	s
	)

Gets a row constraint from the simplex.

Parameters:

	nrow	The row whose constraint we want to get.
	lc	The output linear constraint.
	s	The simplex structure.

Definition at line 269 of file simplex_lpsolve.c.

References AddTerm2LinearConstraint(), InitLinearConstraint(), TSimplex::lp, NEW, SetLinearConstraintError(), SimplexGetRowBounds(), SimplexNColumns(), and SimplexNRows().

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double SimplexGetRowPrimal	(	unsigned int	nrow,
		TSimplex *	s
	)

Gets a row primal value after solving the simplex.

Parameters:

	nrow	The row whose primal value we need.
	s	The simplex structure.

Returns:: The primal value for the row.

Definition at line 297 of file simplex_lpsolve.c.

References TSimplex::lp.

double SimplexGetRowDual	(	unsigned int	nrow,
		TSimplex *	s
	)

Gets a row dual value after solving the simplex.

Parameters:

	nrow	The row whose dual value we need.
	s	The simplex structure.

Returns:: The dual value for the row.

Definition at line 302 of file simplex_lpsolve.c.

References TSimplex::lp.

Referenced by SimplexGetOptimalValue().

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void SimplexAddNewConstraintRaw	(	TLinearConstraint *	lc,
		TSimplex *	s
	)

Adds a row (i.e., a constraint) to the simplex. This function adds the row without any process of the constraint.

The input linear constraint must have the bound properly expanded (see SimplexExpandBounds) before using this function.

Parameters:

	lc	The linear constraint to add to the simplex.
	s	The simplex structure.

See also:: SimplexAddNewConstraint

Definition at line 307 of file simplex_lpsolve.c.

References GetLinearConstraintCoefficients(), GetLinearConstraintError(), GetLinearConstraintVariable(), TSimplex::lp, NEW, PrintInterval(), PrintLinearConstraint(), SimplexNRows(), SimplexSetRowBounds(), and TRUE.

Referenced by SimplexAddNewConstraint().

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void SimplexSetOptimizationFunction	(	TLinearConstraint *	obj,
		TSimplex *	s
	)

Sets a new objective function. We always minimize the objective functions. To maximize just invert the linear constraint before setting it as an optimal function.

Parameters:

	obj	The linear constraint representing the new objective function.
	s	The simplex structure.

See also:: SimplexAddNewConstraint, InvertLinearConstraint.

Definition at line 340 of file simplex_lpsolve.c.

References GetLinearConstraintCoefficient(), GetLinearConstraintCoefficients(), GetLinearConstraintVariable(), GetNumTermsInLinearConstraint(), TSimplex::lp, and NEW.

Referenced by ReduceRange().

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void SimplexGetOptimizationFunction	(	TLinearConstraint *	obj,
		TSimplex *	s
	)

Gets the current objective function.

Parameters:

	obj	The output linear constraint with the current objective function.
	s	The simplex structure.

Definition at line 374 of file simplex_lpsolve.c.

References AddTerm2LinearConstraint(), InitLinearConstraint(), TSimplex::lp, NEW, SimplexNColumns(), and SimplexNRows().

Referenced by SimplexGetOptimalValue().

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double SimplexGetOptimalValueRaw ( TSimplex * s )

Gets the optimal value after optimizing the problem. This function returns the value as given by the simplex engine in use. See SimplexGetOptimalValue for a procedure that adjusts this raw value to get a numerically safe optimal (i.e., it compensates for floating points rounding errors).

Parameters:

s

The simplex structure.