Scippy

SCIP

Solving Constraint Integer Programs

LP Solver Interface

Detailed Description

methods and files provided by the LP solver interface of SCIP

SCIP uses external tools to solve LP relaxations. The communication is realized through an LP interface.

This page lists public interface methods that every LP interface provides. Find the concrete implementation for your LP solver under "src/lpi/".

See also
Available implementations of the LP solver interface for a list of available LP solver interfaces

This file specifies a generic LP solver interface used by SCIP to create, modify, and solve linear programs of the form

min/max obj * x lhs <= A * x <= rhs lb <= x <= ub

and query information about the solution. Although it includes a few SCIP header files, e.g., because it uses SCIP's return codes, it can be used independently of any SCIP instance.

The basis status for (column) variables are as follows:

  • If x_j = lb, then j is at its lower bound (SCIP_BASESTAT_LOWER).
  • If x_j = ub, then j is at its lower bound (SCIP_BASESTAT_UPPER).
  • If x_j is in the basis, it has SCIP_BASESTAT_BASIC status.
  • If x_j is free and non-basic, it has SCIP_BASESTAT_ZERO status.

The basis status for (row) slack variables are:

  • If (A * x)_i = lhs, then i is at its lower bound (SCIP_BASESTAT_LOWER).
  • If (A * x)_i = rhs, then i is at its upper bound (SCIP_BASESTAT_UPPER).
  • If the slack variable for row i is basic, it has SCIP_BASESTAT_BASIC status.

If the solvers use their status differently, those status codes have to be corrected.

In the methods accessing information about the (inverse of the) basis matrix, the interface assumes the following column-oriented format: slack variables of rows have coefficient +1 and the basis matrix is a regular m times m submatrix of (A,I), where m is the number of rows and I is the identity matrix. This means that if, internally, the LP solver uses coefficients -1 for some of the slack variables, then every row associated with a slack variable whose coefficient is -1 should be negated in order to return the result in terms of the LP interface definition.

The creation of a new LP should always be done in the following ways: Either one can use SCIPlpiLoadColLP() or one first adds empty columns or rows. Then the matrix entries can be added by adding columns and rows, respectively. Adding matrix entries for a row or column that have not been added before will result in an error.

The handling of the objective limit is as follows, if supported by the LP-solver: If the objective is larger than the objective limit for minimization problems or smaller than the objective limit for maximization problems, the solution process can be stopped. This naturally occurs in a branch-and-bound process, where the objective limit is set to the value of the best solution found so far. If the problem is a minimization problem and we use the dual simplex, the dual feasible solutions are maximized. If their value are larger than the objective limit, the process can be stopped. In this case, no feasible integer solution can be found in the corresponding branch.

Some LP-solvers also support the opposite setting, but this can easily be checked after the solution process (i.e., for a minimization problem a check whether the optimal value is smaller than the limit). Note that this check can only be determined at the end of the optimization. Thus, we do not support this.

Files

file  lpi.h
 interface methods for specific LP solvers
 

Miscellaneous Methods

const char * SCIPlpiGetSolverName (void)
 
const char * SCIPlpiGetSolverDesc (void)
 
void * SCIPlpiGetSolverPointer (SCIP_LPI *lpi)
 
SCIP_RETCODE SCIPlpiSetIntegralityInformation (SCIP_LPI *lpi, int ncols, int *intInfo)
 
SCIP_Bool SCIPlpiHasPrimalSolve (void)
 
SCIP_Bool SCIPlpiHasDualSolve (void)
 
SCIP_Bool SCIPlpiHasBarrierSolve (void)
 

LPI Creation and Destruction Methods

SCIP_RETCODE SCIPlpiCreate (SCIP_LPI **lpi, SCIP_MESSAGEHDLR *messagehdlr, const char *name, SCIP_OBJSEN objsen)
 
SCIP_RETCODE SCIPlpiFree (SCIP_LPI **lpi)
 

Modification Methods

SCIP_RETCODE SCIPlpiLoadColLP (SCIP_LPI *lpi, SCIP_OBJSEN objsen, int ncols, const SCIP_Real *obj, const SCIP_Real *lb, const SCIP_Real *ub, char **colnames, int nrows, const SCIP_Real *lhs, const SCIP_Real *rhs, char **rownames, int nnonz, const int *beg, const int *ind, const SCIP_Real *val)
 
SCIP_RETCODE SCIPlpiAddCols (SCIP_LPI *lpi, int ncols, const SCIP_Real *obj, const SCIP_Real *lb, const SCIP_Real *ub, char **colnames, int nnonz, const int *beg, const int *ind, const SCIP_Real *val)
 
SCIP_RETCODE SCIPlpiDelCols (SCIP_LPI *lpi, int firstcol, int lastcol)
 
SCIP_RETCODE SCIPlpiDelColset (SCIP_LPI *lpi, int *dstat)
 
SCIP_RETCODE SCIPlpiAddRows (SCIP_LPI *lpi, int nrows, const SCIP_Real *lhs, const SCIP_Real *rhs, char **rownames, int nnonz, const int *beg, const int *ind, const SCIP_Real *val)
 
SCIP_RETCODE SCIPlpiDelRows (SCIP_LPI *lpi, int firstrow, int lastrow)
 
SCIP_RETCODE SCIPlpiDelRowset (SCIP_LPI *lpi, int *dstat)
 
SCIP_RETCODE SCIPlpiClear (SCIP_LPI *lpi)
 
SCIP_RETCODE SCIPlpiChgBounds (SCIP_LPI *lpi, int ncols, const int *ind, const SCIP_Real *lb, const SCIP_Real *ub)
 
SCIP_RETCODE SCIPlpiChgSides (SCIP_LPI *lpi, int nrows, const int *ind, const SCIP_Real *lhs, const SCIP_Real *rhs)
 
SCIP_RETCODE SCIPlpiChgCoef (SCIP_LPI *lpi, int row, int col, SCIP_Real newval)
 
SCIP_RETCODE SCIPlpiChgObjsen (SCIP_LPI *lpi, SCIP_OBJSEN objsen)
 
SCIP_RETCODE SCIPlpiChgObj (SCIP_LPI *lpi, int ncols, const int *ind, const SCIP_Real *obj)
 
SCIP_RETCODE SCIPlpiScaleRow (SCIP_LPI *lpi, int row, SCIP_Real scaleval)
 
SCIP_RETCODE SCIPlpiScaleCol (SCIP_LPI *lpi, int col, SCIP_Real scaleval)
 

Data Accessing Methods

SCIP_RETCODE SCIPlpiGetNRows (SCIP_LPI *lpi, int *nrows)
 
SCIP_RETCODE SCIPlpiGetNCols (SCIP_LPI *lpi, int *ncols)
 
SCIP_RETCODE SCIPlpiGetObjsen (SCIP_LPI *lpi, SCIP_OBJSEN *objsen)
 
SCIP_RETCODE SCIPlpiGetNNonz (SCIP_LPI *lpi, int *nnonz)
 
SCIP_RETCODE SCIPlpiGetCols (SCIP_LPI *lpi, int firstcol, int lastcol, SCIP_Real *lb, SCIP_Real *ub, int *nnonz, int *beg, int *ind, SCIP_Real *val)
 
SCIP_RETCODE SCIPlpiGetRows (SCIP_LPI *lpi, int firstrow, int lastrow, SCIP_Real *lhs, SCIP_Real *rhs, int *nnonz, int *beg, int *ind, SCIP_Real *val)
 
SCIP_RETCODE SCIPlpiGetColNames (SCIP_LPI *lpi, int firstcol, int lastcol, char **colnames, char *namestorage, int namestoragesize, int *storageleft)
 
SCIP_RETCODE SCIPlpiGetRowNames (SCIP_LPI *lpi, int firstrow, int lastrow, char **rownames, char *namestorage, int namestoragesize, int *storageleft)
 
SCIP_RETCODE SCIPlpiGetObj (SCIP_LPI *lpi, int firstcol, int lastcol, SCIP_Real *vals)
 
SCIP_RETCODE SCIPlpiGetBounds (SCIP_LPI *lpi, int firstcol, int lastcol, SCIP_Real *lbs, SCIP_Real *ubs)
 
SCIP_RETCODE SCIPlpiGetSides (SCIP_LPI *lpi, int firstrow, int lastrow, SCIP_Real *lhss, SCIP_Real *rhss)
 
SCIP_RETCODE SCIPlpiGetCoef (SCIP_LPI *lpi, int row, int col, SCIP_Real *val)
 

Solving Methods

SCIP_RETCODE SCIPlpiSolvePrimal (SCIP_LPI *lpi)
 
SCIP_RETCODE SCIPlpiSolveDual (SCIP_LPI *lpi)
 
SCIP_RETCODE SCIPlpiSolveBarrier (SCIP_LPI *lpi, SCIP_Bool crossover)
 
SCIP_RETCODE SCIPlpiStartStrongbranch (SCIP_LPI *lpi)
 
SCIP_RETCODE SCIPlpiEndStrongbranch (SCIP_LPI *lpi)
 
SCIP_RETCODE SCIPlpiStrongbranchFrac (SCIP_LPI *lpi, int col, SCIP_Real psol, int itlim, SCIP_Real *down, SCIP_Real *up, SCIP_Bool *downvalid, SCIP_Bool *upvalid, int *iter)
 
SCIP_RETCODE SCIPlpiStrongbranchesFrac (SCIP_LPI *lpi, int *cols, int ncols, SCIP_Real *psols, int itlim, SCIP_Real *down, SCIP_Real *up, SCIP_Bool *downvalid, SCIP_Bool *upvalid, int *iter)
 
SCIP_RETCODE SCIPlpiStrongbranchInt (SCIP_LPI *lpi, int col, SCIP_Real psol, int itlim, SCIP_Real *down, SCIP_Real *up, SCIP_Bool *downvalid, SCIP_Bool *upvalid, int *iter)
 
SCIP_RETCODE SCIPlpiStrongbranchesInt (SCIP_LPI *lpi, int *cols, int ncols, SCIP_Real *psols, int itlim, SCIP_Real *down, SCIP_Real *up, SCIP_Bool *downvalid, SCIP_Bool *upvalid, int *iter)
 

Solution Information Methods

SCIP_Bool SCIPlpiWasSolved (SCIP_LPI *lpi)
 
SCIP_RETCODE SCIPlpiGetSolFeasibility (SCIP_LPI *lpi, SCIP_Bool *primalfeasible, SCIP_Bool *dualfeasible)
 
SCIP_Bool SCIPlpiExistsPrimalRay (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiHasPrimalRay (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsPrimalUnbounded (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsPrimalInfeasible (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsPrimalFeasible (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiExistsDualRay (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiHasDualRay (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsDualUnbounded (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsDualInfeasible (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsDualFeasible (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsOptimal (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsStable (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsObjlimExc (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsIterlimExc (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsTimelimExc (SCIP_LPI *lpi)
 
int SCIPlpiGetInternalStatus (SCIP_LPI *lpi)
 
SCIP_RETCODE SCIPlpiIgnoreInstability (SCIP_LPI *lpi, SCIP_Bool *success)
 
SCIP_RETCODE SCIPlpiGetObjval (SCIP_LPI *lpi, SCIP_Real *objval)
 
SCIP_RETCODE SCIPlpiGetSol (SCIP_LPI *lpi, SCIP_Real *objval, SCIP_Real *primsol, SCIP_Real *dualsol, SCIP_Real *activity, SCIP_Real *redcost)
 
SCIP_RETCODE SCIPlpiGetPrimalRay (SCIP_LPI *lpi, SCIP_Real *ray)
 
SCIP_RETCODE SCIPlpiGetDualfarkas (SCIP_LPI *lpi, SCIP_Real *dualfarkas)
 
SCIP_RETCODE SCIPlpiGetIterations (SCIP_LPI *lpi, int *iterations)
 
SCIP_RETCODE SCIPlpiGetRealSolQuality (SCIP_LPI *lpi, SCIP_LPSOLQUALITY qualityindicator, SCIP_Real *quality)
 

LP Basis Methods

SCIP_RETCODE SCIPlpiGetBase (SCIP_LPI *lpi, int *cstat, int *rstat)
 
SCIP_RETCODE SCIPlpiSetBase (SCIP_LPI *lpi, const int *cstat, const int *rstat)
 
SCIP_RETCODE SCIPlpiGetBasisInd (SCIP_LPI *lpi, int *bind)
 
SCIP_RETCODE SCIPlpiGetBInvRow (SCIP_LPI *lpi, int r, SCIP_Real *coef, int *inds, int *ninds)
 
SCIP_RETCODE SCIPlpiGetBInvCol (SCIP_LPI *lpi, int c, SCIP_Real *coef, int *inds, int *ninds)
 
SCIP_RETCODE SCIPlpiGetBInvARow (SCIP_LPI *lpi, int r, const SCIP_Real *binvrow, SCIP_Real *coef, int *inds, int *ninds)
 
SCIP_RETCODE SCIPlpiGetBInvACol (SCIP_LPI *lpi, int c, SCIP_Real *coef, int *inds, int *ninds)
 

LPi State Methods

SCIP_RETCODE SCIPlpiGetState (SCIP_LPI *lpi, BMS_BLKMEM *blkmem, SCIP_LPISTATE **lpistate)
 
SCIP_RETCODE SCIPlpiSetState (SCIP_LPI *lpi, BMS_BLKMEM *blkmem, const SCIP_LPISTATE *lpistate)
 
SCIP_RETCODE SCIPlpiClearState (SCIP_LPI *lpi)
 
SCIP_RETCODE SCIPlpiFreeState (SCIP_LPI *lpi, BMS_BLKMEM *blkmem, SCIP_LPISTATE **lpistate)
 
SCIP_Bool SCIPlpiHasStateBasis (SCIP_LPI *lpi, SCIP_LPISTATE *lpistate)
 
SCIP_RETCODE SCIPlpiReadState (SCIP_LPI *lpi, const char *fname)
 
SCIP_RETCODE SCIPlpiWriteState (SCIP_LPI *lpi, const char *fname)
 

LPi Pricing Norms Methods

SCIP_RETCODE SCIPlpiGetNorms (SCIP_LPI *lpi, BMS_BLKMEM *blkmem, SCIP_LPINORMS **lpinorms)
 
SCIP_RETCODE SCIPlpiSetNorms (SCIP_LPI *lpi, BMS_BLKMEM *blkmem, const SCIP_LPINORMS *lpinorms)
 
SCIP_RETCODE SCIPlpiFreeNorms (SCIP_LPI *lpi, BMS_BLKMEM *blkmem, SCIP_LPINORMS **lpinorms)
 

Parameter Methods

SCIP_RETCODE SCIPlpiGetIntpar (SCIP_LPI *lpi, SCIP_LPPARAM type, int *ival)
 
SCIP_RETCODE SCIPlpiSetIntpar (SCIP_LPI *lpi, SCIP_LPPARAM type, int ival)
 
SCIP_RETCODE SCIPlpiGetRealpar (SCIP_LPI *lpi, SCIP_LPPARAM type, SCIP_Real *dval)
 
SCIP_RETCODE SCIPlpiSetRealpar (SCIP_LPI *lpi, SCIP_LPPARAM type, SCIP_Real dval)
 

Numerical Methods

SCIP_Real SCIPlpiInfinity (SCIP_LPI *lpi)
 
SCIP_Bool SCIPlpiIsInfinity (SCIP_LPI *lpi, SCIP_Real val)
 

File Interface Methods

SCIP_RETCODE SCIPlpiReadLP (SCIP_LPI *lpi, const char *fname)
 
SCIP_RETCODE SCIPlpiWriteLP (SCIP_LPI *lpi, const char *fname)
 

Function Documentation

◆ SCIPlpiGetSolverName()

const char* SCIPlpiGetSolverName ( void  )

gets name and version of LP solver

Referenced by doScipCreate(), lpFlushChgCols(), lpFlushChgRows(), SCIPlpCreate(), SCIPlpMarkFlushed(), and SCIPprintVersion().

◆ SCIPlpiGetSolverDesc()

const char* SCIPlpiGetSolverDesc ( void  )

gets description of LP solver (developer, webpage, ...)

Referenced by doScipCreate().

◆ SCIPlpiGetSolverPointer()

void* SCIPlpiGetSolverPointer ( SCIP_LPI lpi)

gets pointer for LP solver - use only with great care

The behavior of this function depends on the solver and its use is therefore only recommended if you really know what you are doing. In general, it returns a pointer to the LP solver object.

Parameters
lpipointer to an LP interface structure

◆ SCIPlpiSetIntegralityInformation()

SCIP_RETCODE SCIPlpiSetIntegralityInformation ( SCIP_LPI lpi,
int  ncols,
int *  intInfo 
)

pass integrality information about variables to the solver

Parameters
lpipointer to an LP interface structure
ncolslength of integrality array
intInfointegrality array (0: continuous, 1: integer). May be NULL iff ncols is 0.

Referenced by lpCopyIntegrality().

◆ SCIPlpiHasPrimalSolve()

SCIP_Bool SCIPlpiHasPrimalSolve ( void  )

informs about availability of a primal simplex solving method

◆ SCIPlpiHasDualSolve()

SCIP_Bool SCIPlpiHasDualSolve ( void  )

informs about availability of a dual simplex solving method

◆ SCIPlpiHasBarrierSolve()

SCIP_Bool SCIPlpiHasBarrierSolve ( void  )

informs about availability of a barrier solving method

◆ SCIPlpiCreate()

SCIP_RETCODE SCIPlpiCreate ( SCIP_LPI **  lpi,
SCIP_MESSAGEHDLR messagehdlr,
const char *  name,
SCIP_OBJSEN  objsen 
)

creates an LP problem object

Parameters
lpipointer to an LP interface structure
messagehdlrmessage handler to use for printing messages, or NULL
nameproblem name
objsenobjective sense

Referenced by addConcaveEstimatorMultivariate(), createLP(), initAlternativeLP(), polyscip::Polyscip::printResults(), SCIP_DECL_PARAMCHGD(), SCIPlpComputeRelIntPoint(), SCIPlpCreate(), solveClassification(), and solveMinIISC().

◆ SCIPlpiFree()

SCIP_RETCODE SCIPlpiFree ( SCIP_LPI **  lpi)

deletes an LP problem object

Parameters
lpipointer to an LP interface structure

Referenced by createLP(), polyscip::Polyscip::printResults(), SCIP_DECL_CONSEXITSOL(), SCIP_DECL_PARAMCHGD(), SCIPlpComputeRelIntPoint(), SCIPlpFree(), sepadataFree(), solveClassification(), and solveMinIISC().

◆ SCIPlpiLoadColLP()

SCIP_RETCODE SCIPlpiLoadColLP ( SCIP_LPI lpi,
SCIP_OBJSEN  objsen,
int  ncols,
const SCIP_Real obj,
const SCIP_Real lb,
const SCIP_Real ub,
char **  colnames,
int  nrows,
const SCIP_Real lhs,
const SCIP_Real rhs,
char **  rownames,
int  nnonz,
const int *  beg,
const int *  ind,
const SCIP_Real val 
)

copies LP data with column matrix into LP solver

Parameters
lpiLP interface structure
objsenobjective sense
ncolsnumber of columns
objobjective function values of columns
lblower bounds of columns
ubupper bounds of columns
colnamescolumn names, or NULL
nrowsnumber of rows
lhsleft hand sides of rows
rhsright hand sides of rows
rownamesrow names, or NULL
nnonznumber of nonzero elements in the constraint matrix
begstart index of each column in ind- and val-array
indrow indices of constraint matrix entries
valvalues of constraint matrix entries

Referenced by polyscip::Polyscip::printResults().

◆ SCIPlpiAddCols()

SCIP_RETCODE SCIPlpiAddCols ( SCIP_LPI lpi,
int  ncols,
const SCIP_Real obj,
const SCIP_Real lb,
const SCIP_Real ub,
char **  colnames,
int  nnonz,
const int *  beg,
const int *  ind,
const SCIP_Real val 
)

adds columns to the LP

Note
ind array is not checked for duplicates, problems may appear if indices are added more than once
Parameters
lpiLP interface structure
ncolsnumber of columns to be added
objobjective function values of new columns
lblower bounds of new columns
ubupper bounds of new columns
colnamescolumn names, or NULL
nnonznumber of nonzero elements to be added to the constraint matrix
begstart index of each column in ind- and val-array, or NULL if nnonz == 0
indrow indices of constraint matrix entries, or NULL if nnonz == 0
valvalues of constraint matrix entries, or NULL if nnonz == 0

Referenced by addAltLPColumn(), computeRelIntPoint(), createAltLPColumn(), createLP(), lpFlushAddCols(), SCIP_DECL_PARAMCHGD(), solveClassification(), and solveMinIISC().

◆ SCIPlpiDelCols()

SCIP_RETCODE SCIPlpiDelCols ( SCIP_LPI lpi,
int  firstcol,
int  lastcol 
)

deletes all columns in the given range from LP

Parameters
lpiLP interface structure
firstcolfirst column to be deleted
lastcollast column to be deleted

Referenced by lpFlushDelCols().

◆ SCIPlpiDelColset()

SCIP_RETCODE SCIPlpiDelColset ( SCIP_LPI lpi,
int *  dstat 
)

deletes columns from SCIP_LPI; the new position of a column must not be greater that its old position

Parameters
lpiLP interface structure
dstatdeletion status of columns input: 1 if column should be deleted, 0 if not output: new position of column, -1 if column was deleted

Referenced by lpDelColset().

◆ SCIPlpiAddRows()

SCIP_RETCODE SCIPlpiAddRows ( SCIP_LPI lpi,
int  nrows,
const SCIP_Real lhs,
const SCIP_Real rhs,
char **  rownames,
int  nnonz,
const int *  beg,
const int *  ind,
const SCIP_Real val 
)

adds rows to the LP

Note
ind array is not checked for duplicates, problems may appear if indices are added more than once
Parameters
lpiLP interface structure
nrowsnumber of rows to be added
lhsleft hand sides of new rows
rhsright hand sides of new rows
rownamesrow names, or NULL
nnonznumber of nonzero elements to be added to the constraint matrix
begstart index of each row in ind- and val-array, or NULL if nnonz == 0
indcolumn indices of constraint matrix entries, or NULL if nnonz == 0
valvalues of constraint matrix entries, or NULL if nnonz == 0

Referenced by addAltLPColumn(), computeRelIntPoint(), createLP(), initAlternativeLP(), lpFlushAddRows(), SCIP_DECL_PARAMCHGD(), solveClassification(), and solveMinIISC().

◆ SCIPlpiDelRows()

SCIP_RETCODE SCIPlpiDelRows ( SCIP_LPI lpi,
int  firstrow,
int  lastrow 
)

deletes all rows in the given range from LP

Parameters
lpiLP interface structure
firstrowfirst row to be deleted
lastrowlast row to be deleted

Referenced by lpFlushDelRows().

◆ SCIPlpiDelRowset()

SCIP_RETCODE SCIPlpiDelRowset ( SCIP_LPI lpi,
int *  dstat 
)

deletes rows from SCIP_LPI; the new position of a row must not be greater that its old position

Parameters
lpiLP interface structure
dstatdeletion status of rows input: 1 if row should be deleted, 0 if not output: new position of row, -1 if row was deleted

Referenced by lpDelRowset().

◆ SCIPlpiClear()

SCIP_RETCODE SCIPlpiClear ( SCIP_LPI lpi)

clears the whole LP

Parameters
lpiLP interface structure

◆ SCIPlpiChgBounds()

SCIP_RETCODE SCIPlpiChgBounds ( SCIP_LPI lpi,
int  ncols,
const int *  ind,
const SCIP_Real lb,
const SCIP_Real ub 
)

changes lower and upper bounds of columns

Parameters
lpiLP interface structure
ncolsnumber of columns to change bounds for
indcolumn indices or NULL if ncols is zero
lbvalues for the new lower bounds or NULL if ncols is zero
ubvalues for the new upper bounds or NULL if ncols is zero

Referenced by fixAltLPVariable(), fixAltLPVariables(), lpFlushChgCols(), lpLexDualSimplex(), runBoundHeuristic(), SCIPcomputeConvexEnvelopeFacet(), SCIPconflictAnalyzeStrongbranch(), unfixAltLPVariable(), and unfixAltLPVariables().

◆ SCIPlpiChgSides()

SCIP_RETCODE SCIPlpiChgSides ( SCIP_LPI lpi,
int  nrows,
const int *  ind,
const SCIP_Real lhs,
const SCIP_Real rhs 
)

changes left and right hand sides of rows

Parameters
lpiLP interface structure
nrowsnumber of rows to change sides for
indrow indices
lhsnew values for left hand sides
rhsnew values for right hand sides

Referenced by lpFlushChgRows(), lpLexDualSimplex(), runBoundHeuristic(), scaleFirstRow(), and SCIPcomputeConvexEnvelopeFacet().

◆ SCIPlpiChgCoef()

SCIP_RETCODE SCIPlpiChgCoef ( SCIP_LPI lpi,
int  row,
int  col,
SCIP_Real  newval 
)

changes a single coefficient

Parameters
lpiLP interface structure
rowrow number of coefficient to change
colcolumn number of coefficient to change
newvalnew value of coefficient

Referenced by updateFirstRow(), updateFirstRowGlobal(), and updateObjUpperbound().

◆ SCIPlpiChgObjsen()

SCIP_RETCODE SCIPlpiChgObjsen ( SCIP_LPI lpi,
SCIP_OBJSEN  objsen 
)

changes the objective sense

Parameters
lpiLP interface structure
objsennew objective sense

◆ SCIPlpiChgObj()

SCIP_RETCODE SCIPlpiChgObj ( SCIP_LPI lpi,
int  ncols,
const int *  ind,
const SCIP_Real obj 
)

changes objective values of columns in the LP

Parameters
lpiLP interface structure
ncolsnumber of columns to change objective value for
indcolumn indices to change objective value for
objnew objective values for columns

Referenced by lpFlushChgCols(), lpLexDualSimplex(), SCIPcomputeConvexEnvelopeFacet(), setAltLPObj(), and setAltLPObjZero().

◆ SCIPlpiScaleRow()

SCIP_RETCODE SCIPlpiScaleRow ( SCIP_LPI lpi,
int  row,
SCIP_Real  scaleval 
)

multiplies a row with a non-zero scalar; for negative scalars, the row's sense is switched accordingly

Parameters
lpiLP interface structure
rowrow number to scale
scalevalscaling multiplier

◆ SCIPlpiScaleCol()

SCIP_RETCODE SCIPlpiScaleCol ( SCIP_LPI lpi,
int  col,
SCIP_Real  scaleval 
)

multiplies a column with a non-zero scalar; the objective value is multiplied with the scalar, and the bounds are divided by the scalar; for negative scalars, the column's bounds are switched

Parameters
lpiLP interface structure
colcolumn number to scale
scalevalscaling multiplier

◆ SCIPlpiGetNRows()

SCIP_RETCODE SCIPlpiGetNRows ( SCIP_LPI lpi,
int *  nrows 
)

gets the number of rows in the LP

Parameters
lpiLP interface structure
nrowspointer to store the number of rows

Referenced by addAltLPColumn(), SCIPcomputeConvexEnvelopeFacet(), SCIPlpFlush(), solveClassification(), and solveMinIISC().

◆ SCIPlpiGetNCols()

SCIP_RETCODE SCIPlpiGetNCols ( SCIP_LPI lpi,
int *  ncols 
)

gets the number of columns in the LP

Parameters
lpiLP interface structure
ncolspointer to store the number of cols

Referenced by addAltLPColumn(), BENDERS_CUTORACLE(), checkIISlocal(), checkLPBoundsClean(), computeRelIntPoint(), extendToCover(), scaleFirstRow(), SCIPcomputeConvexEnvelopeFacet(), SCIPlpFlush(), solveClassification(), and solveMinIISC().

◆ SCIPlpiGetObjsen()

SCIP_RETCODE SCIPlpiGetObjsen ( SCIP_LPI lpi,
SCIP_OBJSEN objsen 
)

gets the objective sense of the LP

Parameters
lpiLP interface structure
objsenpointer to store objective sense

◆ SCIPlpiGetNNonz()

SCIP_RETCODE SCIPlpiGetNNonz ( SCIP_LPI lpi,
int *  nnonz 
)

gets the number of nonzero elements in the LP constraint matrix

Parameters
lpiLP interface structure
nnonzpointer to store the number of nonzeros

◆ SCIPlpiGetCols()

SCIP_RETCODE SCIPlpiGetCols ( SCIP_LPI lpi,
int  firstcol,
int  lastcol,
SCIP_Real lb,
SCIP_Real ub,
int *  nnonz,
int *  beg,
int *  ind,
SCIP_Real val 
)

gets columns from LP problem object; the arrays have to be large enough to store all values; Either both, lb and ub, have to be NULL, or both have to be non-NULL, either nnonz, beg, ind, and val have to be NULL, or all of them have to be non-NULL.

Parameters
lpiLP interface structure
firstcolfirst column to get from LP
lastcollast column to get from LP
lbbuffer to store the lower bound vector, or NULL
ubbuffer to store the upper bound vector, or NULL
nnonzpointer to store the number of nonzero elements returned, or NULL
begbuffer to store start index of each column in ind- and val-array, or NULL
indbuffer to store row indices of constraint matrix entries, or NULL
valbuffer to store values of constraint matrix entries, or NULL

◆ SCIPlpiGetRows()

SCIP_RETCODE SCIPlpiGetRows ( SCIP_LPI lpi,
int  firstrow,
int  lastrow,
SCIP_Real lhs,
SCIP_Real rhs,
int *  nnonz,
int *  beg,
int *  ind,
SCIP_Real val 
)

gets rows from LP problem object; the arrays have to be large enough to store all values. Either both, lhs and rhs, have to be NULL, or both have to be non-NULL, either nnonz, beg, ind, and val have to be NULL, or all of them have to be non-NULL.

Parameters
lpiLP interface structure
firstrowfirst row to get from LP
lastrowlast row to get from LP
lhsbuffer to store left hand side vector, or NULL
rhsbuffer to store right hand side vector, or NULL
nnonzpointer to store the number of nonzero elements returned, or NULL
begbuffer to store start index of each row in ind- and val-array, or NULL
indbuffer to store column indices of constraint matrix entries, or NULL
valbuffer to store values of constraint matrix entries, or NULL

Referenced by scaleFirstRow().

◆ SCIPlpiGetColNames()

SCIP_RETCODE SCIPlpiGetColNames ( SCIP_LPI lpi,
int  firstcol,
int  lastcol,
char **  colnames,
char *  namestorage,
int  namestoragesize,
int *  storageleft 
)

gets column names

Parameters
lpiLP interface structure
firstcolfirst column to get name from LP
lastcollast column to get name from LP
colnamespointers to column names (of size at least lastcol-firstcol+1) or NULL if namestoragesize is zero
namestoragestorage for col names or NULL if namestoragesize is zero
namestoragesizesize of namestorage (if 0, -storageleft returns the storage needed)
storageleftamount of storage left (if < 0 the namestorage was not big enough) or NULL if namestoragesize is zero

◆ SCIPlpiGetRowNames()

SCIP_RETCODE SCIPlpiGetRowNames ( SCIP_LPI lpi,
int  firstrow,
int  lastrow,
char **  rownames,
char *  namestorage,
int  namestoragesize,
int *  storageleft 
)

gets row names

Parameters
lpiLP interface structure
firstrowfirst row to get name from LP
lastrowlast row to get name from LP
rownamespointers to row names (of size at least lastrow-firstrow+1) or NULL if namestoragesize is zero
namestoragestorage for row names or NULL if namestoragesize is zero
namestoragesizesize of namestorage (if 0, -storageleft returns the storage needed)
storageleftamount of storage left (if < 0 the namestorage was not big enough) or NULL if namestoragesize is zero

◆ SCIPlpiGetObj()

SCIP_RETCODE SCIPlpiGetObj ( SCIP_LPI lpi,
int  firstcol,
int  lastcol,
SCIP_Real vals 
)

gets objective coefficients from LP problem object

Parameters
lpiLP interface structure
firstcolfirst column to get objective coefficient for
lastcollast column to get objective coefficient for
valsarray to store objective coefficients

Referenced by lpFlushChgCols(), lpLexDualSimplex(), and SCIPlpMarkFlushed().

◆ SCIPlpiGetBounds()

SCIP_RETCODE SCIPlpiGetBounds ( SCIP_LPI lpi,
int  firstcol,
int  lastcol,
SCIP_Real lbs,
SCIP_Real ubs 
)

gets current bounds from LP problem object

Parameters
lpiLP interface structure
firstcolfirst column to get bounds for
lastcollast column to get bounds for
lbsarray to store lower bound values, or NULL
ubsarray to store upper bound values, or NULL

Referenced by checkLPBoundsClean(), lpFlushChgCols(), lpLexDualSimplex(), and SCIPlpMarkFlushed().

◆ SCIPlpiGetSides()

SCIP_RETCODE SCIPlpiGetSides ( SCIP_LPI lpi,
int  firstrow,
int  lastrow,
SCIP_Real lhss,
SCIP_Real rhss 
)

gets current row sides from LP problem object

Parameters
lpiLP interface structure
firstrowfirst row to get sides for
lastrowlast row to get sides for
lhssarray to store left hand side values, or NULL
rhssarray to store right hand side values, or NULL

Referenced by getFarkasProof(), lpFlushChgRows(), lpLexDualSimplex(), and SCIPlpMarkFlushed().

◆ SCIPlpiGetCoef()

SCIP_RETCODE SCIPlpiGetCoef ( SCIP_LPI lpi,
int  row,
int  col,
SCIP_Real val 
)

gets a single coefficient

Parameters
lpiLP interface structure
rowrow number of coefficient
colcolumn number of coefficient
valpointer to store the value of the coefficient

Referenced by SCIPdummyDebugMethodForSun(), and updateObjUpperbound().

◆ SCIPlpiSolvePrimal()

SCIP_RETCODE SCIPlpiSolvePrimal ( SCIP_LPI lpi)

calls primal simplex to solve the LP

Parameters
lpiLP interface structure

Referenced by checkAltLPInfeasible(), lpLexDualSimplex(), lpPrimalSimplex(), polyscip::Polyscip::printResults(), SCIP_DECL_PARAMCHGD(), and SCIPcomputeConvexEnvelopeFacet().

◆ SCIPlpiSolveDual()

SCIP_RETCODE SCIPlpiSolveDual ( SCIP_LPI lpi)

◆ SCIPlpiSolveBarrier()

SCIP_RETCODE SCIPlpiSolveBarrier ( SCIP_LPI lpi,
SCIP_Bool  crossover 
)

calls barrier or interior point algorithm to solve the LP with crossover to simplex basis

Parameters
lpiLP interface structure
crossoverperform crossover

Referenced by lpBarrier().

◆ SCIPlpiStartStrongbranch()

SCIP_RETCODE SCIPlpiStartStrongbranch ( SCIP_LPI lpi)

start strong branching - call before any strong branching

Parameters
lpiLP interface structure

Referenced by SCIPconflictAnalyzeStrongbranch(), and SCIPlpStartStrongbranch().

◆ SCIPlpiEndStrongbranch()

SCIP_RETCODE SCIPlpiEndStrongbranch ( SCIP_LPI lpi)

end strong branching - call after any strong branching

Parameters
lpiLP interface structure

Referenced by SCIPconflictAnalyzeStrongbranch(), and SCIPlpEndStrongbranch().

◆ SCIPlpiStrongbranchFrac()

SCIP_RETCODE SCIPlpiStrongbranchFrac ( SCIP_LPI lpi,
int  col,
SCIP_Real  psol,
int  itlim,
SCIP_Real down,
SCIP_Real up,
SCIP_Bool downvalid,
SCIP_Bool upvalid,
int *  iter 
)

performs strong branching iterations on one fractional candidate

Parameters
lpiLP interface structure
colcolumn to apply strong branching on
psolfractional current primal solution value of column
itlimiteration limit for strong branchings
downstores dual bound after branching column down
upstores dual bound after branching column up
downvalidstores whether the returned down value is a valid dual bound; otherwise, it can only be used as an estimate value
upvalidstores whether the returned up value is a valid dual bound; otherwise, it can only be used as an estimate value
iterstores total number of strong branching iterations, or -1; may be NULL

Referenced by SCIPcolGetStrongbranch().

◆ SCIPlpiStrongbranchesFrac()

SCIP_RETCODE SCIPlpiStrongbranchesFrac ( SCIP_LPI lpi,
int *  cols,
int  ncols,
SCIP_Real psols,
int  itlim,
SCIP_Real down,
SCIP_Real up,
SCIP_Bool downvalid,
SCIP_Bool upvalid,
int *  iter 
)

performs strong branching iterations on given fractional candidates

Parameters
lpiLP interface structure
colscolumns to apply strong branching on
ncolsnumber of columns
psolsfractional current primal solution values of columns
itlimiteration limit for strong branchings
downstores dual bounds after branching columns down
upstores dual bounds after branching columns up
downvalidstores whether the returned down values are valid dual bounds; otherwise, they can only be used as an estimate values
upvalidstores whether the returned up values are a valid dual bounds; otherwise, they can only be used as an estimate values
iterstores total number of strong branching iterations, or -1; may be NULL

Referenced by SCIPcolGetStrongbranches().

◆ SCIPlpiStrongbranchInt()

SCIP_RETCODE SCIPlpiStrongbranchInt ( SCIP_LPI lpi,
int  col,
SCIP_Real  psol,
int  itlim,
SCIP_Real down,
SCIP_Real up,
SCIP_Bool downvalid,
SCIP_Bool upvalid,
int *  iter 
)

performs strong branching iterations on one candidate with integral value

Parameters
lpiLP interface structure
colcolumn to apply strong branching on
psolcurrent integral primal solution value of column
itlimiteration limit for strong branchings
downstores dual bound after branching column down
upstores dual bound after branching column up
downvalidstores whether the returned down value is a valid dual bound; otherwise, it can only be used as an estimate value
upvalidstores whether the returned up value is a valid dual bound; otherwise, it can only be used as an estimate value
iterstores total number of strong branching iterations, or -1; may be NULL

Referenced by SCIPcolGetStrongbranch().

◆ SCIPlpiStrongbranchesInt()

SCIP_RETCODE SCIPlpiStrongbranchesInt ( SCIP_LPI lpi,
int *  cols,
int  ncols,
SCIP_Real psols,
int  itlim,
SCIP_Real down,
SCIP_Real up,
SCIP_Bool downvalid,
SCIP_Bool upvalid,
int *  iter 
)

performs strong branching iterations on given candidates with integral values

Parameters
lpiLP interface structure
colscolumns to apply strong branching on
ncolsnumber of columns
psolscurrent integral primal solution values of columns
itlimiteration limit for strong branchings
downstores dual bounds after branching columns down
upstores dual bounds after branching columns up
downvalidstores whether the returned down values are valid dual bounds; otherwise, they can only be used as an estimate values
upvalidstores whether the returned up values are a valid dual bounds; otherwise, they can only be used as an estimate values
iterstores total number of strong branching iterations, or -1; may be NULL

Referenced by SCIPcolGetStrongbranches().

◆ SCIPlpiWasSolved()

SCIP_Bool SCIPlpiWasSolved ( SCIP_LPI lpi)

returns whether a solve method was called after the last modification of the LP

Parameters
lpiLP interface structure

Referenced by performStrongbranchWithPropagation(), and SCIPconflictAnalyzeLP().

◆ SCIPlpiGetSolFeasibility()

SCIP_RETCODE SCIPlpiGetSolFeasibility ( SCIP_LPI lpi,
SCIP_Bool primalfeasible,
SCIP_Bool dualfeasible 
)

gets information about primal and dual feasibility of the current LP solution

The feasibility information is with respect to the last solving call and it is only relevant if SCIPlpiWasSolved() returns true. If the LP is changed, this information might be invalidated.

Note that primalfeasible and dualfeasible should only return true if the solver has proved the respective LP to be feasible. Thus, the return values should be equal to the values of SCIPlpiIsPrimalFeasible() and SCIPlpiIsDualFeasible(), respectively. Note that if feasibility cannot be proved, they should return false (even if the problem might actually be feasible).

Parameters
lpiLP interface structure
primalfeasiblepointer to store primal feasibility status
dualfeasiblepointer to store dual feasibility status

Referenced by lpAlgorithm().

◆ SCIPlpiExistsPrimalRay()

SCIP_Bool SCIPlpiExistsPrimalRay ( SCIP_LPI lpi)

returns TRUE iff LP is proven to have a primal unbounded ray (but not necessary a primal feasible point); this does not necessarily mean, that the solver knows and can return the primal ray

Parameters
lpiLP interface structure

Referenced by checkAltLPInfeasible(), and lpSolve().

◆ SCIPlpiHasPrimalRay()

SCIP_Bool SCIPlpiHasPrimalRay ( SCIP_LPI lpi)

returns TRUE iff LP is proven to have a primal unbounded ray (but not necessary a primal feasible point), and the solver knows and can return the primal ray

Parameters
lpiLP interface structure

Referenced by SCIPlpGetPrimalRay(), and SCIPlpGetUnboundedSol().

◆ SCIPlpiIsPrimalUnbounded()

SCIP_Bool SCIPlpiIsPrimalUnbounded ( SCIP_LPI lpi)

returns TRUE iff LP is proven to be primal unbounded

Parameters
lpiLP interface structure

Referenced by checkAltLPInfeasible(), and lpSolve().

◆ SCIPlpiIsPrimalInfeasible()

SCIP_Bool SCIPlpiIsPrimalInfeasible ( SCIP_LPI lpi)

returns TRUE iff LP is proven to be primal infeasible

Parameters
lpiLP interface structure

Referenced by checkAltLPInfeasible(), conflictAnalyzeLP(), getFarkasProof(), lpSolve(), polyscip::Polyscip::printResults(), runBoundHeuristic(), SCIP_DECL_PARAMCHGD(), and SCIPconflictAnalyzeLP().

◆ SCIPlpiIsPrimalFeasible()

SCIP_Bool SCIPlpiIsPrimalFeasible ( SCIP_LPI lpi)

returns TRUE iff LP is proven to be primal feasible

Parameters
lpiLP interface structure

Referenced by lpSolve(), and polyscip::Polyscip::printResults().

◆ SCIPlpiExistsDualRay()

SCIP_Bool SCIPlpiExistsDualRay ( SCIP_LPI lpi)

returns TRUE iff LP is proven to have a dual unbounded ray (but not necessary a dual feasible point); this does not necessarily mean, that the solver knows and can return the dual ray

Parameters
lpiLP interface structure

◆ SCIPlpiHasDualRay()

SCIP_Bool SCIPlpiHasDualRay ( SCIP_LPI lpi)

returns TRUE iff LP is proven to have a dual unbounded ray (but not necessary a dual feasible point), and the solver knows and can return the dual ray

Parameters
lpiLP interface structure

Referenced by getFarkasProof(), lpSolve(), and SCIPlpSolveAndEval().

◆ SCIPlpiIsDualUnbounded()

SCIP_Bool SCIPlpiIsDualUnbounded ( SCIP_LPI lpi)

returns TRUE iff LP is proven to be dual unbounded

Parameters
lpiLP interface structure

◆ SCIPlpiIsDualInfeasible()

SCIP_Bool SCIPlpiIsDualInfeasible ( SCIP_LPI lpi)

returns TRUE iff LP is proven to be dual infeasible

Parameters
lpiLP interface structure

◆ SCIPlpiIsDualFeasible()

SCIP_Bool SCIPlpiIsDualFeasible ( SCIP_LPI lpi)

returns TRUE iff LP is proven to be dual feasible

Parameters
lpiLP interface structure

Referenced by conflictAnalyzeLP(), getFarkasProof(), lpSolve(), performStrongbranchWithPropagation(), and runBoundHeuristic().

◆ SCIPlpiIsOptimal()

SCIP_Bool SCIPlpiIsOptimal ( SCIP_LPI lpi)

returns TRUE iff LP was solved to optimality

Parameters
lpiLP interface structure

Referenced by checkAltLPInfeasible(), computeRelIntPoint(), conflictAnalyzeLP(), lpLexDualSimplex(), and lpSolve().

◆ SCIPlpiIsStable()

SCIP_Bool SCIPlpiIsStable ( SCIP_LPI lpi)

returns TRUE iff current LP solution is stable

This function should return true if the solution is reliable, i.e., feasible and optimal (or proven infeasible/unbounded) with respect to the original problem. The optimality status might be with respect to a scaled version of the problem, but the solution might not be feasible to the unscaled original problem; in this case, SCIPlpiIsStable() should return false.

Parameters
lpiLP interface structure

Referenced by checkAltLPInfeasible(), and lpSolveStable().

◆ SCIPlpiIsObjlimExc()

SCIP_Bool SCIPlpiIsObjlimExc ( SCIP_LPI lpi)

returns TRUE iff the objective limit was reached

Parameters
lpiLP interface structure

Referenced by conflictAnalyzeLP(), getFarkasProof(), lpSolve(), runBoundHeuristic(), and SCIPlpSolveAndEval().

◆ SCIPlpiIsIterlimExc()

SCIP_Bool SCIPlpiIsIterlimExc ( SCIP_LPI lpi)

returns TRUE iff the iteration limit was reached

Parameters
lpiLP interface structure

Referenced by computeRelIntPoint(), lpSolve(), and lpSolveStable().

◆ SCIPlpiIsTimelimExc()

SCIP_Bool SCIPlpiIsTimelimExc ( SCIP_LPI lpi)

returns TRUE iff the time limit was reached

Parameters
lpiLP interface structure

Referenced by computeRelIntPoint(), and lpSolve().

◆ SCIPlpiGetInternalStatus()

int SCIPlpiGetInternalStatus ( SCIP_LPI lpi)

returns the internal solution status of the solver

Parameters
lpiLP interface structure

Referenced by checkAltLPInfeasible(), and lpSolve().

◆ SCIPlpiIgnoreInstability()

SCIP_RETCODE SCIPlpiIgnoreInstability ( SCIP_LPI lpi,
SCIP_Bool success 
)

tries to reset the internal status of the LP solver in order to ignore an instability of the last solving call

Parameters
lpiLP interface structure
successpointer to store, whether the instability could be ignored

Referenced by lpSolveStable().

◆ SCIPlpiGetObjval()

SCIP_RETCODE SCIPlpiGetObjval ( SCIP_LPI lpi,
SCIP_Real objval 
)

gets objective value of solution

Parameters
lpiLP interface structure
objvalstores the objective value

Referenced by conflictAnalyzeLP(), getDualProof(), lpSolve(), performStrongbranchWithPropagation(), runBoundHeuristic(), and SCIPlpSolveAndEval().

◆ SCIPlpiGetSol()

SCIP_RETCODE SCIPlpiGetSol ( SCIP_LPI lpi,
SCIP_Real objval,
SCIP_Real primsol,
SCIP_Real dualsol,
SCIP_Real activity,
SCIP_Real redcost 
)

gets primal and dual solution vectors for feasible LPs

Before calling this function, the caller must ensure that the LP has been solved to optimality, i.e., that SCIPlpiIsOptimal() returns true.

Parameters
lpiLP interface structure
objvalstores the objective value, may be NULL if not needed
primsolprimal solution vector, may be NULL if not needed
dualsoldual solution vector, may be NULL if not needed
activityrow activity vector, may be NULL if not needed
redcostreduced cost vector, may be NULL if not needed

Referenced by BENDERS_CUTORACLE(), computeRelIntPoint(), extendToCover(), getDualProof(), lpLexDualSimplex(), SCIPcomputeConvexEnvelopeFacet(), SCIPlpGetSol(), and SCIPlpGetUnboundedSol().

◆ SCIPlpiGetPrimalRay()

SCIP_RETCODE SCIPlpiGetPrimalRay ( SCIP_LPI lpi,
SCIP_Real ray 
)

gets primal ray for unbounded LPs

Parameters
lpiLP interface structure
rayprimal ray

Referenced by SCIPlpGetPrimalRay(), and SCIPlpGetUnboundedSol().

◆ SCIPlpiGetDualfarkas()

SCIP_RETCODE SCIPlpiGetDualfarkas ( SCIP_LPI lpi,
SCIP_Real dualfarkas 
)

gets dual Farkas proof for infeasibility

Parameters
lpiLP interface structure
dualfarkasdual Farkas row multipliers

Referenced by getFarkasProof(), and SCIPlpGetDualfarkas().

◆ SCIPlpiGetIterations()

SCIP_RETCODE SCIPlpiGetIterations ( SCIP_LPI lpi,
int *  iterations 
)

gets the number of LP iterations of the last solve call

Parameters
lpiLP interface structure
iterationspointer to store the number of iterations of the last solve call

Referenced by conflictAnalyzeLP(), runBoundHeuristic(), SCIPconflictAnalyzeStrongbranch(), and SCIPlpGetIterations().

◆ SCIPlpiGetRealSolQuality()

SCIP_RETCODE SCIPlpiGetRealSolQuality ( SCIP_LPI lpi,
SCIP_LPSOLQUALITY  qualityindicator,
SCIP_Real quality 
)

gets information about the quality of an LP solution

Such information is usually only available, if also a (maybe not optimal) solution is available. The LPI should return SCIP_INVALID for quality, if the requested quantity is not available.

Parameters
lpiLP interface structure
qualityindicatorindicates which quality should be returned
qualitypointer to store quality number

Referenced by checkAltLPInfeasible(), SCIP_DECL_DISPOUTPUT(), and SCIPprintLPSolutionQuality().

◆ SCIPlpiGetBase()

SCIP_RETCODE SCIPlpiGetBase ( SCIP_LPI lpi,
int *  cstat,
int *  rstat 
)

gets current basis status for columns and rows; arrays must be large enough to store the basis status

Parameters
lpiLP interface structure
cstatarray to store column basis status, or NULL
rstatarray to store row basis status, or NULL

Referenced by lpLexDualSimplex(), SCIPconflictAnalyzeStrongbranch(), SCIPlpGetBase(), and SCIPlpGetSol().

◆ SCIPlpiSetBase()

SCIP_RETCODE SCIPlpiSetBase ( SCIP_LPI lpi,
const int *  cstat,
const int *  rstat 
)

sets current basis status for columns and rows

Parameters
lpiLP interface structure
cstatarray with column basis status
rstatarray with row basis status

Referenced by SCIPconflictAnalyzeStrongbranch().

◆ SCIPlpiGetBasisInd()

SCIP_RETCODE SCIPlpiGetBasisInd ( SCIP_LPI lpi,
int *  bind 
)

returns the indices of the basic columns and rows; basic column n gives value n, basic row m gives value -1-m

Parameters
lpiLP interface structure
bindpointer to store basis indices ready to keep number of rows entries

Referenced by SCIPlpGetBasisInd().

◆ SCIPlpiGetBInvRow()

SCIP_RETCODE SCIPlpiGetBInvRow ( SCIP_LPI lpi,
int  r,
SCIP_Real coef,
int *  inds,
int *  ninds 
)

get row of inverse basis matrix B^-1

Note
The LP interface defines slack variables to have coefficient +1. This means that if, internally, the LP solver uses a -1 coefficient, then rows associated with slacks variables whose coefficient is -1, should be negated; see also the explanation in lpi.h.
Parameters
lpiLP interface structure
rrow number
coefpointer to store the coefficients of the row
indsarray to store the non-zero indices, or NULL
nindspointer to store the number of non-zero indices, or NULL (-1: if we do not store sparsity information)

Referenced by SCIPlpGetBInvRow().

◆ SCIPlpiGetBInvCol()

SCIP_RETCODE SCIPlpiGetBInvCol ( SCIP_LPI lpi,
int  c,
SCIP_Real coef,
int *  inds,
int *  ninds 
)

get column of inverse basis matrix B^-1

Note
The LP interface defines slack variables to have coefficient +1. This means that if, internally, the LP solver uses a -1 coefficient, then rows associated with slacks variables whose coefficient is -1, should be negated; see also the explanation in lpi.h.
Parameters
lpiLP interface structure
ccolumn number of B^-1; this is NOT the number of the column in the LP; you have to call SCIPlpiGetBasisInd() to get the array which links the B^-1 column numbers to the row and column numbers of the LP! c must be between 0 and nrows-1, since the basis has the size nrows * nrows
coefpointer to store the coefficients of the column
indsarray to store the non-zero indices, or NULL
nindspointer to store the number of non-zero indices, or NULL (-1: if we do not store sparsity information)

Referenced by SCIPlpGetBInvCol().

◆ SCIPlpiGetBInvARow()

SCIP_RETCODE SCIPlpiGetBInvARow ( SCIP_LPI lpi,
int  r,
const SCIP_Real binvrow,
SCIP_Real coef,
int *  inds,
int *  ninds 
)

get row of inverse basis matrix times constraint matrix B^-1 * A

Note
The LP interface defines slack variables to have coefficient +1. This means that if, internally, the LP solver uses a -1 coefficient, then rows associated with slacks variables whose coefficient is -1, should be negated; see also the explanation in lpi.h.
Parameters
lpiLP interface structure
rrow number
binvrowrow in (A_B)^-1 from prior call to SCIPlpiGetBInvRow(), or NULL
coefvector to return coefficients
indsarray to store the non-zero indices, or NULL
nindspointer to store the number of non-zero indices, or NULL (-1: if we do not store sparsity information)

Referenced by SCIPlpGetBInvARow().

◆ SCIPlpiGetBInvACol()

SCIP_RETCODE SCIPlpiGetBInvACol ( SCIP_LPI lpi,
int  c,
SCIP_Real coef,
int *  inds,
int *  ninds 
)

get column of inverse basis matrix times constraint matrix B^-1 * A

Note
The LP interface defines slack variables to have coefficient +1. This means that if, internally, the LP solver uses a -1 coefficient, then rows associated with slacks variables whose coefficient is -1, should be negated; see also the explanation in lpi.h.
Parameters
lpiLP interface structure
ccolumn number
coefvector to return coefficients
indsarray to store the non-zero indices, or NULL
nindspointer to store the number of non-zero indices, or NULL (-1: if we do not store sparsity information)

Referenced by SCIPlpGetBInvACol().

◆ SCIPlpiGetState()

SCIP_RETCODE SCIPlpiGetState ( SCIP_LPI lpi,
BMS_BLKMEM blkmem,
SCIP_LPISTATE **  lpistate 
)

stores LPi state (like basis information) into lpistate object

Parameters
lpiLP interface structure
blkmemblock memory
lpistatepointer to LPi state information (like basis information)

Referenced by SCIPlpGetState(), and SCIPlpStartDive().

◆ SCIPlpiSetState()

SCIP_RETCODE SCIPlpiSetState ( SCIP_LPI lpi,
BMS_BLKMEM blkmem,
const SCIP_LPISTATE lpistate 
)

loads LPi state (like basis information) into solver; note that the LP might have been extended with additional columns and rows since the state was stored with SCIPlpiGetState()

Parameters
lpiLP interface structure
blkmemblock memory
lpistateLPi state information (like basis information), or NULL

Referenced by SCIPlpSetState().

◆ SCIPlpiClearState()

SCIP_RETCODE SCIPlpiClearState ( SCIP_LPI lpi)

clears current LPi state (like basis information) of the solver

Parameters
lpiLP interface structure

Referenced by SCIPtreeEndProbing().

◆ SCIPlpiFreeState()

SCIP_RETCODE SCIPlpiFreeState ( SCIP_LPI lpi,
BMS_BLKMEM blkmem,
SCIP_LPISTATE **  lpistate 
)

frees LPi state information

Parameters
lpiLP interface structure
blkmemblock memory
lpistatepointer to LPi state information (like basis information)

Referenced by SCIPlpFreeState(), and warmStartInfoFree().

◆ SCIPlpiHasStateBasis()

SCIP_Bool SCIPlpiHasStateBasis ( SCIP_LPI lpi,
SCIP_LPISTATE lpistate 
)

checks, whether the given LPi state contains simplex basis information

Parameters
lpiLP interface structure
lpistateLPi state information (like basis information)

Referenced by SCIPlpSetState().

◆ SCIPlpiReadState()

SCIP_RETCODE SCIPlpiReadState ( SCIP_LPI lpi,
const char *  fname 
)

reads LPi state (like basis information from a file

Parameters
lpiLP interface structure
fnamefile name

◆ SCIPlpiWriteState()

SCIP_RETCODE SCIPlpiWriteState ( SCIP_LPI lpi,
const char *  fname 
)

writes LPi state (i.e. basis information) to a file

Parameters
lpiLP interface structure
fnamefile name

◆ SCIPlpiGetNorms()

SCIP_RETCODE SCIPlpiGetNorms ( SCIP_LPI lpi,
BMS_BLKMEM blkmem,
SCIP_LPINORMS **  lpinorms 
)

stores LPi pricing norms into lpinorms object

Parameters
lpiLP interface structure
blkmemblock memory
lpinormspointer to LPi pricing norms information

Referenced by SCIPlpGetNorms().

◆ SCIPlpiSetNorms()

SCIP_RETCODE SCIPlpiSetNorms ( SCIP_LPI lpi,
BMS_BLKMEM blkmem,
const SCIP_LPINORMS lpinorms 
)

loads LPi pricing norms into solver; note that the LP might have been extended with additional columns and rows since the norms were stored with SCIPlpiGetNorms()

Parameters
lpiLP interface structure
blkmemblock memory
lpinormsLPi pricing norms information, or NULL

Referenced by SCIPlpSetNorms().

◆ SCIPlpiFreeNorms()

SCIP_RETCODE SCIPlpiFreeNorms ( SCIP_LPI lpi,
BMS_BLKMEM blkmem,
SCIP_LPINORMS **  lpinorms 
)

frees LPi pricing norms information

Parameters
lpiLP interface structure
blkmemblock memory
lpinormspointer to LPi pricing norms information, or NULL

Referenced by SCIPlpFreeNorms(), and warmStartInfoFree().

◆ SCIPlpiGetIntpar()

SCIP_RETCODE SCIPlpiGetIntpar ( SCIP_LPI lpi,
SCIP_LPPARAM  type,
int *  ival 
)

gets integer parameter of LP

Parameters
lpiLP interface structure
typeparameter number
ivalbuffer to store the parameter value

Referenced by lpCheckIntpar(), and SCIPlpStartDive().

◆ SCIPlpiSetIntpar()

SCIP_RETCODE SCIPlpiSetIntpar ( SCIP_LPI lpi,
SCIP_LPPARAM  type,
int  ival 
)

sets integer parameter of LP

Parameters
lpiLP interface structure
typeparameter number
ivalparameter value

Referenced by BENDERS_CUTORACLE(), checkAltLPInfeasible(), computeRelIntPoint(), conflictAnalyzeLP(), extendToCover(), initAlternativeLP(), lpSetIntpar(), runBoundHeuristic(), SCIP_DECL_CONSCHECK(), solveClassification(), and solveMinIISC().

◆ SCIPlpiGetRealpar()

SCIP_RETCODE SCIPlpiGetRealpar ( SCIP_LPI lpi,
SCIP_LPPARAM  type,
SCIP_Real dval 
)

gets floating point parameter of LP

Parameters
lpiLP interface structure
typeparameter number
dvalbuffer to store the parameter value

Referenced by conflictAnalyzeLP(), and lpCheckRealpar().

◆ SCIPlpiSetRealpar()

SCIP_RETCODE SCIPlpiSetRealpar ( SCIP_LPI lpi,
SCIP_LPPARAM  type,
SCIP_Real  dval 
)

sets floating point parameter of LP

Parameters
lpiLP interface structure
typeparameter number
dvalparameter value

Referenced by computeRelIntPoint(), conflictAnalyzeLP(), lpSetRealpar(), and runBoundHeuristic().

◆ SCIPlpiInfinity()

◆ SCIPlpiIsInfinity()

SCIP_Bool SCIPlpiIsInfinity ( SCIP_LPI lpi,
SCIP_Real  val 
)

checks if given value is treated as infinity in the LP solver

Parameters
lpiLP interface structure
valvalue to be checked for infinity

Referenced by addBdchg(), checkLPBoundsClean(), and performStrongbranchWithPropagation().

◆ SCIPlpiReadLP()

SCIP_RETCODE SCIPlpiReadLP ( SCIP_LPI lpi,
const char *  fname 
)

reads LP from a file

Parameters
lpiLP interface structure
fnamefile name

◆ SCIPlpiWriteLP()

SCIP_RETCODE SCIPlpiWriteLP ( SCIP_LPI lpi,
const char *  fname 
)

writes LP to a file

Parameters
lpiLP interface structure
fnamefile name

Referenced by addAltLPColumn(), computeRelIntPoint(), SCIP_DECL_PARAMCHGD(), SCIPlpWrite(), solveClassification(), solveMinIISC(), and updateObjUpperbound().