Detailed Description

Usually this class is not used directly, please use one of the concrete implementations of the solver interface.

#include <lemon/lp_base.h>

Inheritance diagram for LpBase:

Classes
class	Col
	Refer to a column of the LP. More...

class	ColIt
	Iterator for iterate over the columns of an LP problem. More...

class	Constr
	Linear constraint. More...

class	DualExpr
	Linear expression of rows. More...

class	Expr
	Linear expression of variables and a constant component. More...

class	Row
	Refer to a row of the LP. More...

class	RowIt
	Iterator for iterate over the rows of an LP problem. More...

class	UnsupportedFormatError
	Unsupported file format exception. More...

Public Types
enum	SolveExitStatus { SOLVED = 0, UNSOLVED = 1 }
	Possible outcomes of an LP solving procedure. More...

enum	Sense { MIN, MAX }
	Direction of the optimization. More...

enum	MessageLevel { MESSAGE_NOTHING, MESSAGE_ERROR, MESSAGE_WARNING, MESSAGE_NORMAL, MESSAGE_VERBOSE }
	Enum for `messageLevel()` parameter. More...

typedef double	Value
	The floating point type used by the solver.

Public Member Functions
virtual	~LpBase ()
	Virtual destructor.

const char *	solverName () const
	Gives back the name of the solver.

Build Up and Modify the LP
Col	addCol ()
	Add a new empty column (i.e a new variable) to the LP.

template<class T >
int	addColSet (T &t)
	Adds several new columns (i.e variables) at once.

void	col (Col c, const DualExpr &e)
	Set a column (i.e a dual constraint) of the LP.

DualExpr	col (Col c) const
	Get a column (i.e a dual constraint) of the LP.

Col	addCol (const DualExpr &e, Value o=0)
	Add a new column to the LP.

Row	addRow ()
	Add a new empty row (i.e a new constraint) to the LP.

template<class T >
int	addRowSet (T &t)
	Add several new rows (i.e constraints) at once.

void	row (Row r, Value l, const Expr &e, Value u)
	Set a row (i.e a constraint) of the LP.

void	row (Row r, const Constr &c)
	Set a row (i.e a constraint) of the LP.

Expr	row (Row r) const
	Get a row (i.e a constraint) of the LP.

Row	addRow (Value l, const Expr &e, Value u)
	Add a new row (i.e a new constraint) to the LP.

Row	addRow (const Constr &c)
	Add a new row (i.e a new constraint) to the LP.

void	erase (Col c)
	Erase a column (i.e a variable) from the LP.

void	erase (Row r)
	Erase a row (i.e a constraint) from the LP.

std::string	colName (Col c) const
	Get the name of a column.

void	colName (Col c, const std::string &name)
	Set the name of a column.

Col	colByName (const std::string &name) const
	Get the column by its name.

std::string	rowName (Row r) const
	Get the name of a row.

void	rowName (Row r, const std::string &name)
	Set the name of a row.

Row	rowByName (const std::string &name) const
	Get the row by its name.

void	coeff (Row r, Col c, Value val)
	Set an element of the coefficient matrix of the LP.

Value	coeff (Row r, Col c) const
	Get an element of the coefficient matrix of the LP.

void	colLowerBound (Col c, Value value)
	Set the lower bound of a column (i.e a variable)

Value	colLowerBound (Col c) const
	Get the lower bound of a column (i.e a variable)

template<class T >
void	colLowerBound (T &t, Value value)
	Set the lower bound of several columns (i.e variables) at once.

void	colUpperBound (Col c, Value value)
	Set the upper bound of a column (i.e a variable)

Value	colUpperBound (Col c) const
	Get the upper bound of a column (i.e a variable)

template<class T >
void	colUpperBound (T &t, Value value)
	Set the upper bound of several columns (i.e variables) at once.

void	colBounds (Col c, Value lower, Value upper)
	Set the lower and the upper bounds of a column (i.e a variable)

template<class T >
void	colBounds (T &t, Value lower, Value upper)
	Set the lower and the upper bound of several columns (i.e variables) at once.

void	rowLowerBound (Row r, Value value)
	Set the lower bound of a row (i.e a constraint)

Value	rowLowerBound (Row r) const
	Get the lower bound of a row (i.e a constraint)

void	rowUpperBound (Row r, Value value)
	Set the upper bound of a row (i.e a constraint)

Value	rowUpperBound (Row r) const
	Get the upper bound of a row (i.e a constraint)

void	objCoeff (Col c, Value v)
	Set an element of the objective function.

Value	objCoeff (Col c) const
	Get an element of the objective function.

void	obj (const Expr &e)
	Set the objective function.

Expr	obj () const
	Get the objective function.

void	sense (Sense sense)
	Set the direction of optimization.

Sense	sense () const
	Query the direction of the optimization.

void	max ()
	Set the sense to maximization.

void	min ()
	Set the sense to maximization.

void	clear ()
	Clear the problem.

void	messageLevel (MessageLevel level)
	Set the message level of the solver.

void	write (std::string file, std::string format="MPS") const
	Write the problem to a file in the given format.

Static Public Member Functions
static int	id (const Col &col)
	Returns the ID of the column.

static Col	colFromId (int id)
	Returns the column with the given ID.

static int	id (const Row &row)
	Returns the ID of the row.

static Row	rowFromId (int id)
	Returns the row with the given ID.

Static Public Attributes
static const Value	INF
	The infinity constant.

static const Value	NaN
	The not a number constant.

Member Enumeration Documentation

enum SolveExitStatus

Enumerator:

SOLVED	= 0. It means that the problem has been successfully solved: either an optimal solution has been found or infeasibility/unboundedness has been proved.
UNSOLVED	= 1. Any other case (including the case when some user specified limit has been exceeded).

enum Sense

Enumerator:

MIN	Minimization.
MAX	Maximization.

enum MessageLevel

Enumerator:

MESSAGE_NOTHING	No output (default value).
MESSAGE_ERROR	Error messages only.
MESSAGE_WARNING	Warnings.
MESSAGE_NORMAL	Normal output.
MESSAGE_VERBOSE	Verbose output.

Member Function Documentation

static Col colFromId ( int id )

inlinestatic

Precondition: The argument should be a valid column ID in the LP problem.

static Row rowFromId ( int id )

inlinestatic

Precondition: The argument should be a valid row ID in the LP problem.

int addColSet ( T & t )

inline

This magic function takes a container as its argument and fills its elements with new columns (i.e. variables)

Parameters

t

can be

a standard STL compatible iterable container with Col as its values_type like
std::vector<LpBase::Col>

std::list<LpBase::Col>
a standard STL compatible iterable container with Col as its mapped_type like
std::map<AnyType,LpBase::Col>
an iterable lemon write map like
ListGraph::NodeMap<LpBase::Col>

ListGraph::ArcMap<LpBase::Col>

Returns: The number of the created column.

void col	(	Col	c,
		const DualExpr &	e
	)

inline

Parameters

c	is the column to be modified
e	is a dual linear expression (see DualExpr) a better one.

DualExpr col ( Col c ) const

inline

Parameters

c	is the column to get

Returns: the dual expression associated to the column

Col addCol	(	const DualExpr &	e,
		Value	o = `0`
	)

inline

Parameters

e	is a dual linear expression (see DualExpr)
o	is the corresponding component of the objective function. It is 0 by default.

Returns: The created column.

Row addRow ( )

inline

This function adds a new empty row (i.e a new constraint) to the LP.

Returns: The created row

int addRowSet ( T & t )

inline

This magic function takes a container as its argument and fills its elements with new row (i.e. variables)

Parameters

t

can be

a standard STL compatible iterable container with Row as its values_type like
std::vector<LpBase::Row>

std::list<LpBase::Row>
a standard STL compatible iterable container with Row as its mapped_type like
std::map<AnyType,LpBase::Row>
an iterable lemon write map like
ListGraph::NodeMap<LpBase::Row>

ListGraph::ArcMap<LpBase::Row>

Returns: The number of rows created.

void row	(	Row	r,
		Value	l,
		const Expr &	e,
		Value	u
	)

inline

Parameters

r	is the row to be modified
l	is lower bound (-INF means no bound)
e	is a linear expression (see Expr)
u	is the upper bound (INF means no bound)

void row	(	Row	r,
		const Constr &	c
	)

inline

Parameters

r	is the row to be modified
c	is a linear expression (see Constr)

Expr row ( Row r ) const

inline

Parameters

r	is the row to get

Returns: the expression associated to the row

Row addRow	(	Value	l,
		const Expr &	e,
		Value	u
	)

inline

Parameters

l	is the lower bound (-INF means no bound)
e	is a linear expression (see Expr)
u	is the upper bound (INF means no bound)

Returns: The created row.

Row addRow ( const Constr & c )

inline

Parameters

c	is a linear expression (see Constr)

Returns: The created row.

void erase ( Col c )

inline

Parameters

c	is the column to be deleted

void erase ( Row r )

inline

Parameters

r	is the row to be deleted

std::string colName ( Col c ) const

inline

Parameters

c	is the coresponding column

Returns: The name of the colunm

void colName	(	Col	c,
		const std::string &	name
	)

inline

Parameters

c	is the coresponding column
name	The name to be given

Col colByName ( const std::string & name ) const

inline

Parameters

name	The name of the column

Returns: the proper column or INVALID

std::string rowName ( Row r ) const

inline

Parameters

r	is the coresponding row

Returns: The name of the row

void rowName	(	Row	r,
		const std::string &	name
	)

inline

Parameters

r	is the coresponding row
name	The name to be given

Row rowByName ( const std::string & name ) const

inline

Parameters

name	The name of the row

Returns: the proper row or INVALID

void coeff	(	Row	r,
		Col	c,
		Value	val
	)

inline

Parameters

r	is the row of the element to be modified
c	is the column of the element to be modified
val	is the new value of the coefficient

Value coeff	(	Row	r,
		Col	c
	)		const

inline

Parameters

r	is the row of the element
c	is the column of the element

Returns: the corresponding coefficient

void colLowerBound	(	Col	c,
		Value	value
	)

inline

The lower bound of a variable (column) has to be given by an extended number of type Value, i.e. a finite number of type Value or -INF.

Value colLowerBound ( Col c ) const

inline

This function returns the lower bound for column (variable) c (this might be -INF as well).

Returns: The lower bound for column c

void colLowerBound	(	T &	t,
		Value	value
	)

inline

This magic function takes a container as its argument and applies the function on all of its elements. The lower bound of a variable (column) has to be given by an extended number of type Value, i.e. a finite number of type Value or -INF.

void colUpperBound	(	Col	c,
		Value	value
	)

inline

The upper bound of a variable (column) has to be given by an extended number of type Value, i.e. a finite number of type Value or INF.

Value colUpperBound ( Col c ) const

inline

This function returns the upper bound for column (variable) c (this might be INF as well).

Returns: The upper bound for column c

void colUpperBound	(	T &	t,
		Value	value
	)

inline

This magic function takes a container as its argument and applies the function on all of its elements. The upper bound of a variable (column) has to be given by an extended number of type Value, i.e. a finite number of type Value or INF.

void colBounds	(	Col	c,
		Value	lower,
		Value	upper
	)

inline

The lower and the upper bounds of a variable (column) have to be given by an extended number of type Value, i.e. a finite number of type Value, -INF or INF.

void colBounds	(	T &	t,
		Value	lower,
		Value	upper
	)

inline

This magic function takes a container as its argument and applies the function on all of its elements. The lower and the upper bounds of a variable (column) have to be given by an extended number of type Value, i.e. a finite number of type Value, -INF or INF.

void rowLowerBound	(	Row	r,
		Value	value
	)

inline

The lower bound of a constraint (row) has to be given by an extended number of type Value, i.e. a finite number of type Value or -INF.

Value rowLowerBound ( Row r ) const

inline

This function returns the lower bound for row (constraint) c (this might be -INF as well).

Returns: The lower bound for row r

void rowUpperBound	(	Row	r,
		Value	value
	)

inline

The upper bound of a constraint (row) has to be given by an extended number of type Value, i.e. a finite number of type Value or -INF.

Value rowUpperBound ( Row r ) const

inline

This function returns the upper bound for row (constraint) c (this might be -INF as well).

Returns: The upper bound for row r

void obj ( const Expr & e )

inline

Parameters

e	is a linear expression of type Expr.

Expr obj ( ) const

inline

Returns: the objective function as a linear expression of type Expr.

void write	(	std::string	file,
		std::string	format = `"MPS"`
	)		const

inline

This function writes the problem to a file in the given format. Different solver backends may support different formats. Trying to write in an unsupported format will trigger UnsupportedFormatError. For the supported formats, visit the documentation of the base class of the related backends (CplexBase, GlpkBase etc.)

Parameters

file	The file path
format	The output file format.

Detailed Description

Classes

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Member Enumeration Documentation

Member Function Documentation