Cbc  2.9.9
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Groups Pages
Public Types | Related Functions | List of all members
CoinWarmStartBasis Class Reference

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

#include <CoinWarmStartBasis.hpp>

+ Inheritance diagram for CoinWarmStartBasis:
+ Collaboration diagram for CoinWarmStartBasis:

Public Types

enum  Status { isFree = 0x00, basic = 0x01, atUpperBound = 0x02, atLowerBound = 0x03 }
 Enum for status of variables. More...
 
typedef CoinTriple< int, int, int > XferEntry
 Transfer vector entry for mergeBasis(const CoinWarmStartBasis*,const XferVec*,const XferVec*) More...
 
typedef std::vector< XferEntryXferVec
 Transfer vector for mergeBasis(const CoinWarmStartBasis*,const XferVec*,const XferVec*) 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. More...
 
int getNumArtificial () const
 Return the number of artificial variables. More...
 
int numberBasicStructurals () const
 Return the number of basic structurals. More...
 
Status getStructStatus (int i) const
 Return the status of the specified structural variable. More...
 
void setStructStatus (int i, Status st)
 Set the status of the specified structural variable. More...
 
char * getStructuralStatus ()
 Return the status array for the structural variables. More...
 
const char * getStructuralStatus () const
 const overload for getStructuralStatus() More...
 
char * getArtificialStatus ()
 As for getStructuralStatus , but returns the status array for the artificial variables. More...
 
Status getArtifStatus (int i) const
 Return the status of the specified artificial variable. More...
 
void setArtifStatus (int i, Status st)
 Set the status of the specified artificial variable. More...
 
const char * getArtificialStatus () const
 const overload for getArtificialStatus() More...
 
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. More...
 
virtual void applyDiff (const CoinWarmStartDiff *const cwsdDiff)
 Apply diff to this basis. More...
 
Methods to modify the warm start object
virtual void setSize (int ns, int na)
 Set basis capacity; existing basis is discarded. More...
 
virtual void resize (int newNumberRows, int newNumberColumns)
 Set basis capacity; existing basis is maintained. More...
 
virtual void compressRows (int tgtCnt, const int *tgts)
 Delete a set of rows from the basis. More...
 
virtual void deleteRows (int rawTgtCnt, const int *rawTgts)
 Delete a set of rows from the basis. More...
 
virtual void deleteColumns (int number, const int *which)
 Delete a set of columns from the basis. More...
 
virtual void mergeBasis (const CoinWarmStartBasis *src, const XferVec *xferRows, const XferVec *xferCols)
 Merge entries from a source basis into this basis. More...
 
Constructors, destructors, and related functions
 CoinWarmStartBasis ()
 Default constructor. More...
 
 CoinWarmStartBasis (int ns, int na, const char *sStat, const char *aStat)
 Constructs a warm start object with the specified status vectors. More...
 
 CoinWarmStartBasis (const CoinWarmStartBasis &ws)
 Copy constructor. More...
 
virtual CoinWarmStartclone () const
 `Virtual constructor' More...
 
virtual ~CoinWarmStartBasis ()
 Destructor. More...
 
virtual CoinWarmStartBasisoperator= (const CoinWarmStartBasis &rhs)
 Assignment. More...
 
virtual void assignBasisStatus (int ns, int na, char *&sStat, char *&aStat)
 Assign the status vectors to be the warm start information. More...
 
Miscellaneous methods
virtual void print () const
 Prints in readable format (for debug) More...
 
bool fullBasis () const
 Returns true if full basis (for debug) More...
 
bool fixFullBasis ()
 Returns true if full basis and fixes up (for debug) More...
 
- Public Member Functions inherited from CoinWarmStart
virtual ~CoinWarmStart ()
 Abstract destructor. More...
 

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. More...
 
int numArtificial_
 The number of artificial variables. More...
 
int maxSize_
 The maximum sise (in ints - actually 4*char) (so resize does not need to do new) More...
 
char * structuralStatus_
 The status of the structural variables. More...
 
char * artificialStatus_
 The status of the artificial variables. More...
 

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. More...
 
void setStatus (char *array, int i, CoinWarmStartBasis::Status st)
 Set the status of the specified variable in the given status array. More...
 
const char * statusName (CoinWarmStartBasis::Status status)
 Generate a print string for a status code. More...
 

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 40 of file CoinWarmStartBasis.hpp.

Member Typedef Documentation

typedef std::vector<XferEntry> CoinWarmStartBasis::XferVec

Member Enumeration Documentation

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 i%4 == 0, bits 2:3 if i%4 == 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 57 of file CoinWarmStartBasis.hpp.

Constructor & Destructor Documentation

CoinWarmStartBasis::CoinWarmStartBasis ( )

Default constructor.

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

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 87 of file CoinWarmStartBasis.hpp.

int CoinWarmStartBasis::getNumArtificial ( ) const
inline

Return the number of artificial variables.

Definition at line 90 of file CoinWarmStartBasis.hpp.

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 99 of file CoinWarmStartBasis.hpp.

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

Set the status of the specified structural variable.

Definition at line 105 of file CoinWarmStartBasis.hpp.

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 116 of file CoinWarmStartBasis.hpp.

const char* CoinWarmStartBasis::getStructuralStatus ( ) const
inline

const overload for getStructuralStatus()

Definition at line 123 of file CoinWarmStartBasis.hpp.

char* CoinWarmStartBasis::getArtificialStatus ( )
inline

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

Definition at line 128 of file CoinWarmStartBasis.hpp.

Status CoinWarmStartBasis::getArtifStatus ( int  i) const
inline

Return the status of the specified artificial variable.

Definition at line 131 of file CoinWarmStartBasis.hpp.

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

Set the status of the specified artificial variable.

Definition at line 137 of file CoinWarmStartBasis.hpp.

const char* CoinWarmStartBasis::getArtificialStatus ( ) const
inline

const overload for getArtificialStatus()

Definition at line 148 of file CoinWarmStartBasis.hpp.

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.

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.

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 AbcWarmStart.

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 AbcWarmStart.

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 AbcWarmStart.

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 AbcWarmStart.

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.

Reimplemented in AbcWarmStart.

virtual void CoinWarmStartBasis::mergeBasis ( const CoinWarmStartBasis src,
const XferVec xferRows,
const XferVec xferCols 
)
virtual

Merge entries from a source basis into this basis.

Warning
It's the client's responsibility to ensure validity of the merged basis, if that's important to the application.

The vector xferCols (xferRows) specifies runs of entries to be taken from the source basis and placed in this basis. Each entry is a CoinTriple, with first specifying the starting source index of a run, second specifying the starting destination index, and third specifying the run length.

virtual CoinWarmStart* CoinWarmStartBasis::clone ( ) const
inlinevirtual

`Virtual constructor'

Implements CoinWarmStart.

Reimplemented in AbcWarmStart.

Definition at line 284 of file CoinWarmStartBasis.hpp.

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 AbcWarmStart.

virtual void CoinWarmStartBasis::print ( ) const
virtual

Prints in readable format (for debug)

bool CoinWarmStartBasis::fullBasis ( ) const

Returns true if full basis (for debug)

bool CoinWarmStartBasis::fixFullBasis ( )

Returns true if full basis and fixes up (for debug)

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 351 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 360 of file CoinWarmStartBasis.hpp.

const char * statusName ( CoinWarmStartBasis::Status  status)
related

Generate a print string for a status code.

Member Data Documentation

int CoinWarmStartBasis::numStructural_
protected

The number of structural variables.

Definition at line 334 of file CoinWarmStartBasis.hpp.

int CoinWarmStartBasis::numArtificial_
protected

The number of artificial variables.

Definition at line 336 of file CoinWarmStartBasis.hpp.

int CoinWarmStartBasis::maxSize_
protected

The maximum sise (in ints - actually 4*char) (so resize does not need to do new)

Definition at line 338 of file CoinWarmStartBasis.hpp.

char* CoinWarmStartBasis::structuralStatus_
protected

The status of the structural variables.

Definition at line 340 of file CoinWarmStartBasis.hpp.

char* CoinWarmStartBasis::artificialStatus_
protected

The status of the artificial variables.

Definition at line 342 of file CoinWarmStartBasis.hpp.


The documentation for this class was generated from the following file: