SoPlex: LPRow Class Reference

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(In)equality for LPs.Class LPRow provides constraints for linear programs in the form

$l \le a^Tx \le r,$

where a is a DSVector. l is referred to as left hand side, r as right hand side and a as row vector or the constraint vector. l and r may also take values $\pm$ infinity. This static member is predefined, but may be overridden to meet the needs of the LP solver to be used. More...

#include <lprow.h>

Public Types
Types
enum	Type { LESS_EQUAL, EQUAL, GREATER_EQUAL, RANGE }
	(In)Equality of an LP row. More...

Public Member Functions
Construction / destruction
	LPRow (int defDim=0)
	Construct LPRow with a vector ready to hold `defDim` nonzeros.

	LPRow (const LPRow &row)
	copy constructor

	LPRow (Real p_lhs, const SVector &p_rowVector, Real p_rhs)
	Construct LPRow with the given left-hand side, right-hand side and rowVector.

	LPRow (const SVector &p_rowVector, Type p_type, Real p_value)
	Construct LPRow from passed `rowVector`, `type` and `value`.

	~LPRow ()
	destructor

Access / modification
Type	type () const
	get type of row.

void	setType (Type p_type)
	set type of (in)equality

Real	value () const
	Right hand side value of (in)equality.

Real	lhs () const
	get left-hand side value.

void	setLhs (Real p_left)
	access left-hand side value.

Real	rhs () const
	get right-hand side value.

void	setRhs (Real p_right)
	access right-hand side value.

const SVector &	rowVector () const
	get constraint row vector

void	setRowVector (const DSVector &p_vec)
	access constraint row vector.

Consistency check
bool	isConsistent () const
	check consistency.

Private Attributes
Data
Real	left
	left-hand side of the constraint

Real	right
	right-hand side of the constraint

DSVector	vec
	the row vector

Detailed Description

(In)equality for LPs.

Class LPRow provides constraints for linear programs in the form

$l \le a^Tx \le r,$

where a is a DSVector. l is referred to as left hand side, r as right hand side and a as row vector or the constraint vector. l and r may also take values $\pm$ infinity. This static member is predefined, but may be overridden to meet the needs of the LP solver to be used.

LPRows allow to specify regular inequalities of the form

$a^Tx \sim \alpha,$

where $\sim$ can take any value of $\le, =, \ge$ , by setting rhs and lhs to the same value or setting one of them to $\infty$ .

Since constraints in the regular form occur often, LPRows offers methods type() and value() for retreiving $\sim$ and $\alpha$ of an LPRow in this form, respectively. Also, a constructor for LPRows given in regular form is provided.

Definition at line 57 of file lprow.h.

Member Enumeration Documentation

enum Type

(In)Equality of an LP row.

LPRows may be of one of the above Types. This datatype may be used for constructing new LPRows in the regular form.

Enumerator
LESS_EQUAL	$a^Tx \le \alpha$ .
EQUAL	$a^Tx = \alpha$ .
GREATER_EQUAL	$a^Tx \ge \alpha$ .
RANGE	$\lambda \le a^Tx \le \rho$ .

Definition at line 78 of file lprow.h.

Constructor & Destructor Documentation

LPRow ( int defDim = 0 )

explicit

Construct LPRow with a vector ready to hold defDim nonzeros.

Definition at line 91 of file lprow.h.

References LPRow::isConsistent().

LPRow ( const LPRow & row )

copy constructor

Definition at line 98 of file lprow.h.

References LPRow::isConsistent().

LPRow	(	Real	p_lhs,
		const SVector &	p_rowVector,
		Real	p_rhs
	)

Construct LPRow with the given left-hand side, right-hand side and rowVector.

Definition at line 106 of file lprow.h.

References LPRow::isConsistent().

LPRow	(	const SVector &	p_rowVector,
		LPRow::Type	p_type,
		Real	p_value
	)

Construct LPRow from passed rowVector, type and value.

Definition at line 71 of file lprow.cpp.

References LPRow::EQUAL, LPRow::GREATER_EQUAL, soplex::infinity, LPRow::isConsistent(), LPRow::left, LPRow::LESS_EQUAL, and LPRow::right.

~LPRow ( )

destructor

Definition at line 116 of file lprow.h.

Member Function Documentation

bool isConsistent ( ) const

check consistency.

Definition at line 177 of file lprow.h.

References DSVector::isConsistent(), and LPRow::vec.

Referenced by LPRow::LPRow().

Real lhs ( ) const

get left-hand side value.

Definition at line 137 of file lprow.h.

References LPRow::left.

Referenced by LPRowSet::add(), SPxLP::changeRow(), LPRow::setType(), LPRow::type(), and LPRow::value().

Real rhs ( ) const

get right-hand side value.

Definition at line 149 of file lprow.h.

References LPRow::right.

Referenced by LPRowSet::add(), SPxLP::changeRow(), LPRow::setType(), LPRow::type(), and LPRow::value().

const SVector& rowVector ( ) const

get constraint row vector

Definition at line 161 of file lprow.h.

References LPRow::vec.

Referenced by LPRowSet::add(), SPxLP::changeRow(), and SPxLP::doAddRow().

void setLhs ( Real p_left )

access left-hand side value.

Definition at line 143 of file lprow.h.

References LPRow::left.

Referenced by SPxLP::getRow(), SPxLP::readLPF(), and soplex::readRows().

void setRhs ( Real p_right )

access right-hand side value.

Definition at line 155 of file lprow.h.

References LPRow::right.

Referenced by SPxLP::getRow(), SPxLP::readLPF(), and soplex::readRows().

void setRowVector ( const DSVector & p_vec )

access constraint row vector.

Definition at line 167 of file lprow.h.

References LPRow::vec.

Referenced by SPxLP::getRow(), and SPxLP::readLPF().

void setType ( LPRow::Type p_type )

set type of (in)equality

Definition at line 39 of file lprow.cpp.

References LPRow::EQUAL, LPRow::GREATER_EQUAL, soplex::infinity, LPRow::left, LPRow::LESS_EQUAL, LPRow::lhs(), MSG_ERROR, LPRow::RANGE, LPRow::rhs(), LPRow::right, and soplex::spxout.

LPRow::Type type ( ) const

get type of row.

Definition at line 28 of file lprow.cpp.

References LPRow::EQUAL, LPRow::GREATER_EQUAL, soplex::infinity, LPRow::LESS_EQUAL, LPRow::lhs(), LPRow::RANGE, and LPRow::rhs().

Referenced by LPRow::value().

Real value ( ) const

Right hand side value of (in)equality.

This method returns $\alpha$ for a LPRow in regular form. However, value() may only be called for LPRows with type() != RANGE.

Definition at line 64 of file lprow.cpp.

References soplex::infinity, LPRow::lhs(), LPRow::RANGE, LPRow::rhs(), and LPRow::type().

Member Data Documentation

Real left

private

left-hand side of the constraint

Definition at line 64 of file lprow.h.

Referenced by LPRow::lhs(), LPRow::LPRow(), LPRow::setLhs(), and LPRow::setType().

Real right

private

right-hand side of the constraint

Definition at line 65 of file lprow.h.

Referenced by LPRow::LPRow(), LPRow::rhs(), LPRow::setRhs(), and LPRow::setType().

private

the row vector

Definition at line 66 of file lprow.h.

Referenced by LPRow::isConsistent(), LPRow::rowVector(), and LPRow::setRowVector().