CoinWarmStartBasis Class Reference

The default COIN simplex (basis-oriented) warm start class. More...

#include <CoinWarmStartBasis.hpp>

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List of all members.

Public Types

 isFree = 0x00
 Nonbasic free variable.
 basic = 0x01
 Basic variable.
 atUpperBound = 0x02
 Nonbasic at upper bound.
 atLowerBound = 0x03
 Nonbasic at lower bound.
enum  Status { isFree = 0x00, basic = 0x01, atUpperBound = 0x02, atLowerBound = 0x03 }
 Enum for status of variables. More...

Public Member Functions

Methods to get and set basis information.
The status of variables is kept in a pair of arrays, one for structural variables, and one for artificials (aka logicals and slacks). The status is coded using the values of the Status enum.

See also:
CoinWarmStartBasis::Status for a description of the packing used in the status arrays.


int getNumStructural () const
 Return the number of structural variables.
int getNumArtificial () const
 Return the number of artificial variables.
int numberBasicStructurals () const
 Return the number of basic structurals.
Status getStructStatus (int i) const
 Return the status of the specified structural variable.
void setStructStatus (int i, Status st)
 Set the status of the specified structural variable.
char * getStructuralStatus ()
 Return the status array for the structural variables.
const char * getStructuralStatus () const
 const overload for getStructuralStatus()
char * getArtificialStatus ()
 As for getStructuralStatus , but returns the status array for the artificial variables.
Status getArtifStatus (int i) const
 Return the status of the specified artificial variable.
void setArtifStatus (int i, Status st)
 Set the status of the specified artificial variable.
const char * getArtificialStatus () const
 const overload for getArtificialStatus()
Basis `diff' methods
virtual CoinWarmStartDiffgenerateDiff (const CoinWarmStart *const oldCWS) const
 Generate a `diff' that can convert the warm start basis passed as a parameter to the warm start basis specified by this.
virtual void applyDiff (const CoinWarmStartDiff *const cwsdDiff)
 Apply diff to this basis.
Methods to modify the warm start object
virtual void setSize (int ns, int na)
 Set basis capacity; existing basis is discarded.
virtual void resize (int newNumberRows, int newNumberColumns)
 Set basis capacity; existing basis is maintained.
virtual void compressRows (int tgtCnt, const int *tgts)
 Delete a set of rows from the basis.
virtual void deleteRows (int rawTgtCnt, const int *rawTgts)
 Delete a set of rows from the basis.
virtual void deleteColumns (int number, const int *which)
 Delete a set of columns from the basis.
Constructors, destructors, and related functions
 CoinWarmStartBasis ()
 Default constructor.
 CoinWarmStartBasis (int ns, int na, const char *sStat, const char *aStat)
 Constructs a warm start object with the specified status vectors.
 CoinWarmStartBasis (const CoinWarmStartBasis &ws)
 Copy constructor.
virtual CoinWarmStartclone () const
 `Virtual constructor'
virtual ~CoinWarmStartBasis ()
 Destructor.
virtual CoinWarmStartBasisoperator= (const CoinWarmStartBasis &rhs)
 Assignment.
virtual void assignBasisStatus (int ns, int na, char *&sStat, char *&aStat)
 Assign the status vectors to be the warm start information.
Miscellaneous methods
virtual void print () const
 Prints in readable format (for debug).

Protected Attributes

Protected data members
See also:
CoinWarmStartBasis::Status for a description of the packing used in the status arrays.


int numStructural_
 The number of structural variables.
int numArtificial_
 The number of artificial variables.
char * structuralStatus_
 The status of the structural variables.
char * artificialStatus_
 The status of the artificial variables.

Related Functions

(Note that these are not member functions.)

CoinWarmStartBasis::Status getStatus (const char *array, int i)
 Get the status of the specified variable in the given status array.
void setStatus (char *array, int i, CoinWarmStartBasis::Status st)
 Set the status of the specified variable in the given status array.

Detailed Description

The default COIN simplex (basis-oriented) warm start class.

CoinWarmStartBasis provides for a warm start object which contains the status of each variable (structural and artificial).

Todo:
Modify this class so that the number of status entries per byte and bytes per status vector allocation unit are not hardcoded. At the least, collect this into a couple of macros.
Todo:
Consider separate fields for allocated capacity and actual basis size. We could avoid some reallocation, at the price of retaining more space than we need. Perhaps more important, we could do much better sanity checks.

Definition at line 35 of file CoinWarmStartBasis.hpp.


Member Enumeration Documentation

enum CoinWarmStartBasis::Status

Enum for status of variables.

Matches CoinPrePostsolveMatrix::Status, without superBasic. Most code that converts between CoinPrePostsolveMatrix::Status and CoinWarmStartBasis::Status will break if this correspondence is broken.

The status vectors are currently packed using two bits per status code, four codes per byte. The location of the status information for variable i is in byte i>>2 and occupies bits 0:1 if i4 == 0, bits 2:3 if i4 == 1, etc. The non-member functions getStatus(const char*,int) and setStatus(char*,int,CoinWarmStartBasis::Status) are provided to hide details of the packing.

Enumerator:
isFree  Nonbasic free variable.
basic  Basic variable.
atUpperBound  Nonbasic at upper bound.
atLowerBound  Nonbasic at lower bound.

Definition at line 52 of file CoinWarmStartBasis.hpp.


Constructor & Destructor Documentation

CoinWarmStartBasis::CoinWarmStartBasis (  ) 

Default constructor.

Creates a warm start object representing an empty basis (0 rows, 0 columns).

Referenced by clone().

CoinWarmStartBasis::CoinWarmStartBasis ( int  ns,
int  na,
const char *  sStat,
const char *  aStat 
)

Constructs a warm start object with the specified status vectors.

The parameters are copied. Consider assignBasisStatus(int,int,char*&,char*&) if the object should assume ownership.

See also:
CoinWarmStartBasis::Status for a description of the packing used in the status arrays.

CoinWarmStartBasis::CoinWarmStartBasis ( const CoinWarmStartBasis ws  ) 

Copy constructor.

virtual CoinWarmStartBasis::~CoinWarmStartBasis (  )  [virtual]

Destructor.


Member Function Documentation

int CoinWarmStartBasis::getNumStructural (  )  const [inline]

Return the number of structural variables.

Definition at line 72 of file CoinWarmStartBasis.hpp.

References numStructural_.

int CoinWarmStartBasis::getNumArtificial (  )  const [inline]

Return the number of artificial variables.

Definition at line 75 of file CoinWarmStartBasis.hpp.

References numArtificial_.

int CoinWarmStartBasis::numberBasicStructurals (  )  const

Return the number of basic structurals.

A fast test for an all-slack basis.

Status CoinWarmStartBasis::getStructStatus ( int  i  )  const [inline]

Return the status of the specified structural variable.

Definition at line 84 of file CoinWarmStartBasis.hpp.

References structuralStatus_.

void CoinWarmStartBasis::setStructStatus ( int  i,
Status  st 
) [inline]

Set the status of the specified structural variable.

Definition at line 90 of file CoinWarmStartBasis.hpp.

References structuralStatus_.

char* CoinWarmStartBasis::getStructuralStatus (  )  [inline]

Return the status array for the structural variables.

The status information is stored using the codes defined in the Status enum, 2 bits per variable, packed 4 variables per byte.

Definition at line 101 of file CoinWarmStartBasis.hpp.

References structuralStatus_.

const char* CoinWarmStartBasis::getStructuralStatus (  )  const [inline]

const overload for getStructuralStatus()

Definition at line 108 of file CoinWarmStartBasis.hpp.

References structuralStatus_.

char* CoinWarmStartBasis::getArtificialStatus (  )  [inline]

As for getStructuralStatus , but returns the status array for the artificial variables.

Definition at line 113 of file CoinWarmStartBasis.hpp.

References artificialStatus_.

Status CoinWarmStartBasis::getArtifStatus ( int  i  )  const [inline]

Return the status of the specified artificial variable.

Definition at line 116 of file CoinWarmStartBasis.hpp.

References artificialStatus_.

void CoinWarmStartBasis::setArtifStatus ( int  i,
Status  st 
) [inline]

Set the status of the specified artificial variable.

Definition at line 122 of file CoinWarmStartBasis.hpp.

References artificialStatus_.

const char* CoinWarmStartBasis::getArtificialStatus (  )  const [inline]

const overload for getArtificialStatus()

Definition at line 133 of file CoinWarmStartBasis.hpp.

References artificialStatus_.

virtual CoinWarmStartDiff* CoinWarmStartBasis::generateDiff ( const CoinWarmStart *const   oldCWS  )  const [virtual]

Generate a `diff' that can convert the warm start basis passed as a parameter to the warm start basis specified by this.

The capabilities are limited: the basis passed as a parameter can be no larger than the basis pointed to by this.

Reimplemented from CoinWarmStart.

Reimplemented in OsiDylpWarmStartBasis.

virtual void CoinWarmStartBasis::applyDiff ( const CoinWarmStartDiff *const   cwsdDiff  )  [virtual]

Apply diff to this basis.

Update this basis by applying diff. It's assumed that the allocated capacity of the basis is sufficiently large.

Reimplemented from CoinWarmStart.

Reimplemented in OsiDylpWarmStartBasis.

virtual void CoinWarmStartBasis::setSize ( int  ns,
int  na 
) [virtual]

Set basis capacity; existing basis is discarded.

After execution of this routine, the warm start object does not describe a valid basis: all structural and artificial variables have status isFree.

Reimplemented in OsiDylpWarmStartBasis.

virtual void CoinWarmStartBasis::resize ( int  newNumberRows,
int  newNumberColumns 
) [virtual]

Set basis capacity; existing basis is maintained.

After execution of this routine, the warm start object describes a valid basis: the status of new structural variables (added columns) is set to nonbasic at lower bound, and the status of new artificial variables (added rows) is set to basic. (The basis can be invalid if new structural variables do not have a finite lower bound.)

Reimplemented in OsiDylpWarmStartBasis.

virtual void CoinWarmStartBasis::compressRows ( int  tgtCnt,
const int *  tgts 
) [virtual]

Delete a set of rows from the basis.

Warning:
This routine assumes that the set of indices to be deleted is sorted in ascending order and contains no duplicates. Use deleteRows() if this is not the case.

The resulting basis is guaranteed valid only if all deleted constraints are slack (hence the associated logicals are basic).

Removal of a tight constraint with a nonbasic logical implies that some basic variable must be made nonbasic. This correction is left to the client.

Reimplemented in OsiDylpWarmStartBasis.

virtual void CoinWarmStartBasis::deleteRows ( int  rawTgtCnt,
const int *  rawTgts 
) [virtual]

Delete a set of rows from the basis.

Warning:
The resulting basis is guaranteed valid only if all deleted constraints are slack (hence the associated logicals are basic).
Removal of a tight constraint with a nonbasic logical implies that some basic variable must be made nonbasic. This correction is left to the client.

Reimplemented in OsiDylpWarmStartBasis.

virtual void CoinWarmStartBasis::deleteColumns ( int  number,
const int *  which 
) [virtual]

Delete a set of columns from the basis.

Warning:
The resulting basis is guaranteed valid only if all deleted variables are nonbasic.
Removal of a basic variable implies that some nonbasic variable must be made basic. This correction is left to the client.

virtual CoinWarmStart* CoinWarmStartBasis::clone (  )  const [inline, virtual]

`Virtual constructor'

Implements CoinWarmStart.

Reimplemented in OsiDylpWarmStartBasis.

Definition at line 253 of file CoinWarmStartBasis.hpp.

References CoinWarmStartBasis().

virtual CoinWarmStartBasis& CoinWarmStartBasis::operator= ( const CoinWarmStartBasis rhs  )  [virtual]

Assignment.

virtual void CoinWarmStartBasis::assignBasisStatus ( int  ns,
int  na,
char *&  sStat,
char *&  aStat 
) [virtual]

Assign the status vectors to be the warm start information.

In this method the CoinWarmStartBasis object assumes ownership of the pointers and upon return the argument pointers will be NULL. If copying is desirable, use the array constructor or the assignment operator .

Note:
The pointers passed to this method will be freed using delete[], so they must be created using new[].

Reimplemented in OsiDylpWarmStartBasis.

virtual void CoinWarmStartBasis::print (  )  const [virtual]

Prints in readable format (for debug).

Reimplemented in OsiDylpWarmStartBasis.


Friends And Related Function Documentation

CoinWarmStartBasis::Status getStatus ( const char *  array,
int  i 
) [related]

Get the status of the specified variable in the given status array.

Definition at line 314 of file CoinWarmStartBasis.hpp.

void setStatus ( char *  array,
int  i,
CoinWarmStartBasis::Status  st 
) [related]

Set the status of the specified variable in the given status array.

Definition at line 323 of file CoinWarmStartBasis.hpp.


Member Data Documentation

int CoinWarmStartBasis::numStructural_ [protected]

The number of structural variables.

Definition at line 299 of file CoinWarmStartBasis.hpp.

Referenced by getNumStructural().

int CoinWarmStartBasis::numArtificial_ [protected]

The number of artificial variables.

Definition at line 301 of file CoinWarmStartBasis.hpp.

Referenced by getNumArtificial().

char* CoinWarmStartBasis::structuralStatus_ [protected]

The status of the structural variables.

Definition at line 303 of file CoinWarmStartBasis.hpp.

Referenced by getStructStatus(), getStructuralStatus(), and setStructStatus().

char* CoinWarmStartBasis::artificialStatus_ [protected]

The status of the artificial variables.

Definition at line 305 of file CoinWarmStartBasis.hpp.

Referenced by getArtificialStatus(), getArtifStatus(), and setArtifStatus().


The documentation for this class was generated from the following file:
Generated on Thu May 15 22:00:34 2008 by  doxygen 1.4.7