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1. CPX_PARAM_STRONGCANDLIM 2045 int Any positive number IloCplex StrongCandLim mip limits strongcand Default 10 Description MIP candidate list Controls the length of the candidate list when CPLEX uses the setting strong branching variable selection set mip strategy variableselect 3 CPX PARAM STRONGITLIM int 0 Automatic Let CPLEX determine automatically or any positive integer IloCplex StrongItLim mip limits strongit Default 0 Description MIP simplex iterations Controls the number of simplex iterations performed on each variable in the candidate list when CPLEX uses the setting strong branching variable selection set mip strategy variableselect 3 The default setting 0 chooses the iteration limit automatically 36 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name CPX_PARAM_STRONGTHREADLIM IloCplex StrongThreadLim mip limits strongthreads Description MIP parallel threads Code Type Controls the number of parallel threads used to perform strong branching Note that this parameter does nothing if the MIP thread limit set mip limits threads is greater than 1 Note also that the global thread limit CPX PARAM THREADS does not affect this parameter Value Symbolic Constants Any positive number Default 1 IloCplex SubMIPNodeLim mip limits submipnodelim CPX PARAM SUBALG 2026 1 0 CPX ALG AUTOM
2. ILOG CPLEX 9 0 PARAMETERS 29 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_PPRIIND 1029 int IloCplex PPriInd simplex pgradient 1 CPX PPRIIND PARTIAL Reduced cost pricing O CPX PPRIIND AUTO Hybrid reduced cost amp devex pricing 1 CPX PPRIIND DEVEX Devex pricing 2 CPX PPRIIND STEEP Steepest edge pricing 3 CPX PPRIIND STEEPOSTART Steepest edge pricing with slack initial norms 4 CPX_PPRIIND_FULL Full pricing Default 0 Description Primal Simplex pricing algorithm The default pricing 0 usually provides the fastest solution time but many problems benefit from alternative settings CPX PARAM PRECOMPRESS 1066 int 1 Off IloCplex PreCompress 0 Automatic preprocessing compress 1 On Default 0 Description Compression of original model after presolve Specifies whether CPLEX should compress the original model after presolve is performed This can save considerable storage space for large models Under the automatic setting CPLEX will decide whether to perform the compression based on model characteristics CPX PARAM PREDUAL 1044 int 1 Off IloCplex PreDual 0 Automatic preprocessing dual 1 On Default 0 Description Presolve dual setting Determines whether CPLEX Presolve should pass the primal or dual linear programming problem to the linear programming optimization algorithm By d
3. E UBCOVERS 22 EURFREQ 22 IISIND 22 ILOG CPLEX 9 0 PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA PX PA QOoQo000090000000000000000000000000000000000900m00 20D x lt RA RA RA RA RA RA RA _ _ RAM RAM RAM RAM IMPLBD 22 INTSOLLIM 23 ITLIM23 LPMETHOD 23 DISPLAY 24 PEMPHASIS 24 INTERVAL 25 RDIND 25 PORDTYPE 25 PSTART 25 PTHREADS 25 RCUTS 26 DISPLAY 26 POPT 26 ETEPRHS 26 ETFIND 27 ETITLIM 27 ETPPRIIND 27 ODEFILEIND 27 ODELIM 28 ODESEL 28 ZGROWTH 28 ZREADLIM 28 OBJDIF 29 OBJLLIM 29 OBJULIM 29 RIND 29 RLIM 29 RIIND 30 PRECOMPRESS 30 DUAL 30 IND 30 PRELINEAR 31 PASS 31 LVND 31 ELIM 31 HHHHHHHH U E T c Ap U PSDIND 32 THOD 32 GROWTH 32 READLIM 33 EDUCE 33 EINV 33 RELAXPREIND 33
4. CPX_PARAM_NODELIM int Any nonnegative integer IloCplex NodeLim mip limits nodes Default BIGINT Description MIP node limit Sets the maximum number of nodes solved before the algorithm terminates without reaching optimality When set to 0 zero CPLEX does not create any nodes but it does solve the root node LP relaxation and repeatedly apply cuts and resolve this LP CPX PARAM NODESEL 2018 1 0 CPX_NODESEL_DFS Depth first search IloCplex NodeSel 1 CPX NODESEL BESTBOUND Best bound search mip strategy nodeselect 2 CPX NODESEL BESTEST Best estimate search 3 CPX NODESEL BESTEST ALT Alternative best estimate search Default 1 Description MIP node selection strategy Used to set the rule for selecting the next node to process when backtracking The depth first search strategy chooses the most recently created node The best bound strategy chooses the node with the best objective function for the associated LP relaxation The best estimate strategy selects the node with the best estimate of the integer objective value that would be obtained from a node once all integer infeasibilities are removed An alternative best estimate search is also available CPX PARAM NZGROWTH int Any integer from 0 to 268 435 450 IloCplex NzGrowth read nonzeros Default 500 Description Nonzero element memory growth Sets the growth policy for subsequent mo
5. Changing the rules of business ILOG CPLEX 9 0 Parameters October 2003 Copyright 1987 2003 ILOG S A All rights reserved Table of Contents Parameters of LOG CPLEX cece 5 Parameter Names ica neh edhe baa ee ee a tebe od 6 Correspondence of 7 Saving Parameter Settings to a 7 Parameter cece eee ee eee renee ence ee hh hmm 8 ILOG CPLEX 9 0 PARAMETERS 3 CONTENTS 4 ILOG CPLEX 9 0 PARAMETERS Parameters of ILOG CPLEX The behavior of ILOG CPLEX is controlled by a variety of parameters that are each accessible and settable by the user This manual lists these parameters and explains their settings in the CPLEX Component Libraries and the Interactive Optimizer It also explains how to read and write parameter settings of the Callable Library to a file in Saving Parameter Settings to a File on page 7 The following methods set and access parameters for objects of the Concert Technology class IloCplex in C and Java setParam getParam getMin getMax getDefault setDefaults The names of the corresponding accessors in the class 1 in C NET follow the usual conventions of names and capitalization in that language and framework ILOG CPLEX 9 0 PARAMETERS 5 Callable Library programs C and other languages acce
6. RELOBUDIF 33 PARAMETERS PX PARAM REVERSEIND 34 PX PARAM RINSHEUR 34 PX PARAM ROWGROWTH 34 PX PARAM ROWREADLIM 34 PX PARAM SCAIND 34 PX PARAM SCRIND 35 PX PARAM SIFTALG 35 PX PARAM SIFTDISPLAY 35 PX PARAM SIFTITLIM 35 PX PARAM SIMDISPLAY 35 PX PARAM SINGLIM 36 PX PARAM STARTALG 36 PX PARAM STRONGCANDLIM 36 PX PARAM STRONGITLIM 36 PX PARAM STRONGTHREADLIM 37 PX PARAM SUBALG 37 PX PARAM SUBMIPNODELIM 37 PX PARAM SYMMETRY 37 PX PARAM THREADS 37 PX PARAM TILIM 38 PX PARAM TRELIM 38 PX PARAM VARSEL 39 PX PARAM WORKDIR 39 PX PARAM WORKMEM 39 CPX PARAM XXXIND 40 Concert Technology AdvInd9 AggCutLim9 AggFill9 AggInd9 BarAlg 10 BarColNz 10 BarCrossAlg 10 BarDisplay 10 BarEpComp 11 BarGrowth 11 BarItLim 11 BarMaxCor 11 BarObjRng 12 12 BarOrder 12 BarQCPEpComp 12 BarStartAlg 13 BarThreads 13 BasInterval 13 CY 2 0 QUO CY CE Gv OQ CO SY QV QUO i0 0 0 x6 OQ CE ILOG CPLEX 9 0 INDEX BBInterval 13 BndStrenInd 14 BrDir 14 BtTol 14 Cliques 15 ClockType 15 CoeRedInd 15 ColGrowth 15 ColReadLim 15 Covers 16 CraInd 16 CutLo 16 CutPass 16 CutsFactor 17 CutUp 17 DataCheck 17 DepInd 17 DisjCuts 18 DiveType 18 DPriInd 18 EpAGap 19 EpGap 19 EpInt 19 EpMrk 19 EpOpt 19 EpPer 20 EpRHS 20 FinalFactor 20 FlowCovers 20 FlowPaths 21 FracCand 21 FracCuts 21 FracPass 21 GUBCovers 22 HeurFreq 22 I
7. mip strategy heuristicfreq or any positive integer Default 0 Description MIP heuristic frequency Determines how often to apply the periodic heuristic Setting the value to 1 turns off the periodic heuristic Setting the value to 0 the default applies the periodic heuristic at an interval chosen automatically Setting the value to a positive number applies the heuristic at the requested node interval For example setting HEURISTICFREQ to 20 dictates that the heuristic be called at node 0 20 40 60 etc CPX PARAM IISIND 1018 Jint O Algorithm with minimum computation time IloCplex IISInd 1 Algorithm generating smaller IIS set simplex iisfind Default 0 Description IIS algorithm indicator Determines the algorithm to be used to identify the IIS set see the ILOG CPLEX User s Manual for a description of the CPLEX Infeasibility Finder The default algorithm is faster and works best for most problems However if the size of the resulting IIS is large the alternative algorithm may be useful The resulting IIS is smaller although more computation time is usually needed CPX PARAM IMPLBD 2041 int 1 Do not generate implied bound cuts IloCplex ImplBd 0 Automatically determined mip cuts implied 1 Generate implied bound cuts moderately 2 Generate implied bound cuts aggressively Default 0 Description MIP implied bound cuts indicator Determines whether or not to generate implied bound cuts for the problem
8. 1 0 IloCplex BtTol mip strategy backtrack Default 0 9999 Description Backtracking tolerance Controls how often backtracking is done during the branching process The decision when to backtrack depends on three values that change during the course of the optimization the objective function value of the best integer feasible solution incumbent the best remaining objective function value of any unexplored node best node the objective function value of the most recently solved node current objective If a cutoff tolerance see CPX_PARAM_CUTUP and CPX PARAM CUTLO has been set by the user then that value is used as the incumbent until an integer feasible solution is found The target gap is defined to be the absolute value of the difference between the incumbent and the best node multiplied by this backtracking parameter CPLEX does not backtrack until the absolute value of the difference between the objective of the current node and the best node is at least as large as the target gap Low values of this backtracking parameter thus tend to increase the amount of backtracking which makes the search process more of a pure best bound search Higher parameter values tend to decrease backtracking making the search more of a pure depth first search The backtracking value has effect only after an integer feasible solution is found or when a cutoff has been specified Note that this backtracking value merely permits backtr
9. 1 Generate Gomory fractional cuts moderately 2 Generate Gomory fractional cuts aggressively Default 0 Description MIP Gomory fractional cuts indicator Determines whether or not Gomory fractional cuts should be generated for the problem Setting the value to 0 the default indicates that the attempt to generate Gomory fractional cuts should continue only if it seems to be helping CPX PARAM FRACPASS 2050 lint 0 Automatic IloCplex FracPass or any positive integer mip limits gomorypass Default 0 Description Pass limit for generating Gomory fractional cuts Limits the number of passes for generating Gomory fractional cuts At the default setting of 0 CPLEX decides The parameter is ignored if the Gomory fractional cut parameter PARAM FRACCUTS is set to a nonzero value ILOG CPLEX 9 0 PARAMETERS 21 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX PARAM GUBCOVERS 2044 1 1 Do not generate GUB cuts IloCplex GUBCovers 0 Automatically determined mip cuts gubcovers 1 Generate GUB cuts moderately 2 Generate GUB cuts aggressively Default 0 Description MIP GUB cuts indicator Determines whether or not to generate GUB cuts for the problem Setting the value to 0 the default indicates that the attempt to generate GUB cuts should continue only if it seems to be helping CPX PARAM HEURFREQ 2031 int 1 None IloCplex HeurFreq 0 Automatic
10. Setting the value to 0 the default indicates that the attempt to generate implied bound cuts should continue only if it seems to be helping 22 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_INTSOLLIM 2015 Jint IloCplex IntSolLim mip limits solutions Any positive integer Default BIGINT Description MIP solution limit Sets the number of MIP solutions to be found before stopping CPX PARAM ITLIM 1020 int Any nonnegative integer IloCplex ItLim simplex limits iterations Default BIGINT Description Simplex maximum iteration limit Sets the maximum number of iterations to be performed before the algorithm terminates without reaching optimality When set to 0 zero no simplex method iteration occurs However CPLEX factors the initial basis from which solution routines provide information about the associated initial solution CPX PARAM LPMETHOD 1062 int CPX ALG AUTOMATIC Automatic IloCplex RootAlg 1 CPX ALG PRIMAL Primal Simplex lpmethod 2 CPX ALG DUAL Dual Simplex 3 CPX ALG NET Network Simplex 4 CPX ALG BARRIER Barrier 5 6 B CPX ALG SIFTING Sifting CPX ALG CONCURRENT Concurrent Dual arrier and Primal Default 0 Description Algorithm for linear optimization Determines which algorithm is used when CPX1popt or optimize in the Interactive Optimizer is
11. based on the problem and its progress CPX PARAM WORKDIR 1064 string Default IloCplex WorkDir workdir Description Directory for working files Specifies the name of an existing directory into which CPLEX may store temporary working files such as for MIP node files or for out of core barrier CPX PARAM WORKMEM 1065 double Any nonnegative number in megabytes IloCplex WorkMem workmem Default 128 0 Description Memory available for working storage Specifies an upper limit on the amount of central memory in megabytes that CPLEX is permitted to use for working files see PARAM WORKDIR ILOG CPLEX 9 0 PARAMETERS 39 PARAMETER TABLE Parameter Name CPX_PARAM_XXXIND IloCplex XXXInd simplex xxxstart Code Type int Description Indicator for reading xxx files Used to enable disable the reading of xxx files When solving a linear program using a simplex optimizer option PRIMOPT or TRANOPT if for some reason the optimization as well as the CPLEX session were terminated before completion it may be useful to read an xxx file to resume optimization However if preprocessing was used during the optimization just reading in this basis file does not produce the desired behavior since the xxx file was generated relative to the presolved problem The XXXSTART indicator provides an alternative approach If this indicator is turned on CPLEX activates its presolve and tur
12. invoked Currently the behavior of the Automatic setting is that CPLEX almost always invokes the dual simplex algorithm The one exception is when solving the relaxation of an MILP model when multiple threads have been requested In this case the Automatic setting will use the concurrent optimization algorithm The Automatic setting may be expanded in the future so that CPLEX chooses the algorithm based on additional problem characteristics ILOG CPLEX 9 0 PARAMETERS 23 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX PARAM MIPDISPLAY 2012 int IloCplex MIPDisplay mip display 0 No display 1 Display integer feasible solutions 2 Display nodes under CPX PARAM MIPInterval 3 Same as 2 with information on node cuts 4 Same as 3 with LP subproblem information at root 5 Same as 4 with LP subproblem information at nodes Default 2 Description MIP node log display information Determines what CPLEX reports to the screen during mixed integer optimization The amount of information displayed increases with increasing values of this parameter A setting of 0 causes no node log to be displayed until the optimal solution is found A setting of 1 displays an entry for each integer feasible solution found Each entry contains the objective function value the node count the number of unexplored nodes in the tree and the current optimality gap A setting of 2 also generates an entry for every n th
13. lowerobj Default 1e 75 Description Lower objective value limit Setting a lower objective function limit causes CPLEX to halt the optimization process once the minimum objective function value limit has been exceeded This limit applies only during Phase II of the simplex algorithm CPX PARAM OBJULIM 1026 double Any number IloCplex 0ObjULim simplex limits upperobj Default 1 72 Description Upper objective value limit Setting an upper objective function limit causes CPLEX to halt the optimization process once the maximum objective function value limit has been exceeded This limit applies only during Phase II of the simplex algorithm CPX PARAM PERIND 1027 0 cPx Off IloCplex PerInd 1 CPx_ON On simplex perturbation Default 0 Description Simplex perturbation indicator Setting this parameter to 1 causes all problems to be automatically perturbed as optimization begins A setting of 0 allows CPLEX to determine dynamically during solution whether progress is slow enough to merit a perturbation The situations in which a setting of 1 helps are rare and restricted to problems that exhibit extreme degeneracy CPX PARAM PERLIM 1028 int 0 Determined automatically IloCplex PerLim or any positive integer simplex limits perturbation Default 0 Description Simplex perturbation limit Sets the number of stalled iterations before perturbation is performed
14. number of times or until no more reductions are possible At the default value of 1 Presolve should continue only if it seems to be helping CPX PARAM PRESLVND 2037 int 1 No node presolve IloCplex PreslvNd 0 Automatic mip strategy presolvenod 1 Force node presolve Default 0 Description Node presolve selector Indicates whether node presolve should be performed at the nodes of a mixed integer programming solution Node presolve can significantly reduce solution time for some models The default setting is generally effective at determining whether to apply node presolve although runtimes can be reduced for some models by turning node presolve off CPX PARAM PRICELIM 1010 int 0 Determined automatically IloCplex PriceLim or any positive integer simplex pricing Default 0 Description Simplex pricing candidate list size Sets the maximum number of variables kept in the pricing candidate list ILOG CPLEX 9 0 PARAMETERS 31 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_PROBE 2042 int 1 No probing IloCplex Probe 0 Automatic mip strategy probe 1 3 Probing level Default 0 Description MIP probe Determines the amount of probing on variables to be performed before MIP branching Higher settings perform more probing Probing can be very powerful but very time consuming at the start Setting the parameter to values above the default
15. reduce the solution time of fixed MIPs CPX PARAM AGGCUTLIM 2054 int Any nonnegative integer IloCplex AggCutLim mip limits aggforcut Default 3 Description Constraint aggregation limit for cut generation Limits the number of constraints that can be aggregated for generating flow cover and mixed integer rounding cuts CPX PARAM AGGFILL 1002 1 Any nonnegative integer IloCplex AggFill preprocessing fill Default 10 Description Preprocessing aggregator fill Limits variable substitutions by the aggregator If the net result of a single substitution is more nonzeros than this value the substitution is not made CPX PARAM AGGIND 1003 1 Automatic 1 for LP infinite for MIP IloCplex AggInd 0 Do not use any aggregator preprocessing aggregator Any positive integer Default 1 Description Preprocessing aggregator application limit Invokes the aggregator to use substitution where possible to reduce the number of rows and columns before the problem is solved If set to a positive value the aggregator is applied the specified number of times or until no more reductions are possible ILOG CPLEX 9 0 PARAMETERS 9 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_BARALG 3007 int 0 Default setting IloCplex BarAlg 1 Infeasibility estimate start barrier algorithm 2 Infeasibility constant start 3 Standard barrier Default 0 Description
16. 36 as MIP subproblem LP algorithm 37 as sifting subproblem algorithm 35 extraction level 27 feasibility tolerance 26 global time limit 38 logging display indicator 26 optimality tolerance 26 simplex iteration limit 27 simplex pricing algorithm 27 P parameter correspondence in APIs 7 methods to access 5 naming conventions 6 save settings in file 7 Q QCP convergence tolerance 12 QP algorithm for continuous quadratic optimization 32 convergence tolerance 11 PARAMETERS indefinite MIQP indicator 32 positive semi definiteness and 32 Q matrix memory growth 32 Q matrix nonzero read limit 33 simplex crash ordering for 16 S sifting as algorithm for linear optimization 23 as MIP starting LP algorithm 36 as MIP subproblem LP algorithm 37 display information 35 subproblem algorithm 35 upper limit on iterations 35 simplex as algorithm for linear optimization 23 as MIP starting LP algorithm 36 as MIP subproblem LP algorithm 37 as QP algorithm at root 32 as sifting subproblem algorithm 35 basis file saving frequency 13 crash ordering 16 dual pricing algorithm 18 feasibility tolerance 20 final factor 20 global time limit 38 irreducibly inconsistent set IIS algorithm indicator 22 iteration display information 35 iterations in MIP 36 lower objective value limit 29 Markowitz tolerance 19 maximum iteration limit 23 network extraction level 27 network iteration limit 27 network pricing algorithm 27 optimality
17. 5 mip cuts covers 16 mip cuts disjunctive 18 mip cuts flowcuts 20 mip cuts gomory 21 mip cuts gubcovers 22 mip cuts implied 22 mip cuts mircut 26 mip cuts pathcut 21 mip display 24 PARAMETERS mip emphasis 24 mip interval 25 mip lim submipnodes 37 mip limits aggforcut 9 mip limits cutpasses 16 mip limits cutsfactor17 mip limits gomorycand 21 mip limits gomorypass 21 mip limits nodes 28 mip limits solutions 23 mip limits strongcand 36 mip limits strongit 36 mip limits strongthreads 37 mip limits threads 25 mip limits treememory 38 mip ordertype 25 mip strategy backtrack 14 mip strategy bbinterval 13 mip strategy branch 14 mip strategy dive 18 mip strategy file 27 mip strategy heuristicfreq 22 mip strategy mipstart 25 mip strategy nodeselect 28 mip strategy order 25 mip strategy presolvenode 31 mip strategy probe 32 mip strategy rinsheur 34 mip strategy startalgorithm 36 mip strategy subalgorithm37 mip strategy variableselect 39 mip tolerances absmipgap 19 mip tolerances integrality 19 mip tolerances lowercutoff 16 mip tolerances mipgap 19 mip tolerances objdifference 29 mip tolerances relobjdifference 33 mip tolerances uppercutoff17 network display 26 network iterations 27 network netfind 27 network pricing 27 network tolerances feasibility 26 network tolerances optimality 26 preprocessing aggregator 9 ILOG CPLEX 9 0 INDEX preprocessing boundstrength 14
18. ARAM BARITLIM int O No Barrier iterations or any positive integer IloCplex BarItLim barrier limits iterations Default BIGINT Description Barrier iteration limit Sets the number of barrier iterations before termination When set to 0 no barrier iterations occur but problem setup occurs and information about the setup is displayed such as Cholesky factoring information CPX PARAM BARMAXCOR 3013 int 1 Automatically determined IloCplex BarMaxCor 0 None barrier limits corrections or any positive integer Default 1 Description Barrier maximum correction limit Sets the maximum number of centering corrections done on each iteration An explicit value greater than 0 may improve the numerical performance of the algorithm at the expense of computation time ILOG CPLEX 9 0 PARAMETERS 11 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_BAROBJRNG 3004 double Any nonnegative number IloCplex BarObjRng barrier limits objrange Default 1 20 Description Barrier objective range Sets the maximum absolute value of the objective function The barrier algorithm looks at this limit to detect unbounded problems CPX PARAM BAROOC 3019 int 0 CPX OFF Off IloCplex BarOOC 1 CPX_ON On barrier outofcore Default 0 Description Out of core barrier indicator Specifies whether the barrier optimizer should use out of core storage on disk for the Cholesky fac
19. ARAMETERS 37 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_TILIM 1039 double Any nonnegative number IloCplex TiLim timelimit Default 1e 75 Description Global time limit Sets the maximum time in seconds for a call to an optimizer This time limit applies also to the infeasibility finder The time is measured in terms of either CPU time or elapsed time according to the setting of the CLOCKTYPE parameter The time limit for an optimizer applies to the sum of all its steps such as preprocessing crossover and internal calls to other optimizers In a sequence of calls to optimizers the limit is not cumulative but applies to each call individually For example if you set a time limit of 10 seconds and you call mipopt twice then there could be a total of at most 20 seconds of running time if each call consumes its maximum allotment CPX PARAM TRELIM 2027 double Any nonnegative number IloCplex TreLim mip limits treememory Default 1 72 Description Tree memory limit Sets an absolute upper limit on the size in megabytes of the branch amp cut tree If this limit is exceeded CPLEX terminates optimization 38 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants 1 CPX VARSEL MININFEAS Branch on variable with minimum infeasibility 0 VARSEL DEFAULT Branch variable automatically s
20. ATIC Let CPLEX choose IloCplex NodeAlg 1 CPX ALG PRIMAL Primal Simplex mip strategy subalgorithm 2 CPX ALG DUAL Dual Simplex 3 CPX ALG NET Network Simplex 4 CPX ALG BARRIER Barrier 5 CPX ALG SIFTING Sifting Default 0 Description MIP subproblem LP algorithm Sets the algorithm to be used on MIP subproblems CPX PARAM SUBMIPNODELIM 2062 41 Any positive integer Default 500 Description MIP subnode limit heuristic Restricts the number of nodes searched during application of the relaxation induced neighborhood search RINS CPX PARAM SYMMETRY IloCplex Symmetry preprocessing symmetry Description Symmetry breaking cuts Determines whether symmetry breaking cuts may be added during the preprocessing phase to a MIP model CPX PARAM THREADS IloCplex Threads threads 2059 1067 int int 0 CPX OFF Off 1 CPX ON On Default Off Minimum 1 Maximum determined by license key and computer Default 1 Description Global default thread count ILOG CPLEX 9 0 Determines the default number of parallel processes threads that will be invoked by any CPLEX parallel optimizer This provides a convenient way to control parallelism with a single parameter setting The value in place for this parameter can be overridden for any particular CPLEX parallel optimizer by setting the appropriate thread limit CPX_PARAM_BARTHREADS CPX PARAM MIPTHRI EADS Or P
21. Barrier algorithm The default setting 0 uses the infeasibility estimate start algorithm setting 1 when solving subproblems in a MIP problem and the standard barrier algorithm setting 3 in other cases The standard barrier algorithm is almost always fastest However on problems that are primal or dual infeasible common for MIP subproblems the standard algorithm may not work as well as the alternatives The two alternative algorithms settings 1 and 2 may eliminate numerical difficulties related to infeasibility but are generally slower CPX PARAM BARCOLNZ 3009 0 Dynamically calculated IloCplex BarColNz or any positive integer barrier colnonzeros Default 0 Description Barrier column nonzeros Used in the recognition of dense columns If columns in the presolved and aggregated problem exist with more entries than this value such columns are considered dense and are treated specially by the CPLEX Barrier Optimizer to reduce their effect If the problem contains fewer than 400 rows dense column handling is NOT initiated CPX PARAM BARCROSSALG 3018 11 1 No crossover IloCplex BarCrossAlg 0 Automatic barrier crossover 1 Primal crossover 2 Dual crossover Default 0 Description Barrier crossover algorithm Determines which if any crossover is performed at the end of a barrier optimization called via CPXhybbaropt CPX PARAM BARDISPLAY 3010 int 0 No progress information IloCplex BarDisplay 1 N
22. EPMRK 1013 double Any number from 0 0001 to 0 99999 IloCplex EpMrk simplex tolerances markowitz Default 0 01 Description Markowitz tolerance Influences pivot selection during basis factoring Increasing the Markowitz threshold may improve the numerical properties of the solution CPX PARAM EPOPT 1014 IloCplex EpOpt simplex tolerances optimality double Any number from 1e to 1e Default 1 06 Description Optimality tolerance Influences the reduced cost tolerance for optimality This parameter governs how closely CPLEX must approach the theoretically optimal solution ILOG CPLEX 9 0 PARAMETERS 19 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_EPPER 1015 double Any positive number gt 1 e8 IloCplex EpPer simplex perturbation Default 1e Description Perturbation constant Sets the amount by which CPLEX perturbs the upper and lower bounds on the variables when a problem is perturbed This parameter can be set to a smaller value if the default value creates too large a change in the problem CPX PARAM EPRHS 1016 double Any number from 1 9 to 1e IloCplex EpRHS simplex tolerances feasibility Default 1 06 Description Feasibility tolerance The feasibility tolerance specifies the degree to which a problem s basic variables may violate their bounds FEASIBILITY influences the selection of an optimal basis and can be r
23. ERS 2040 1 1 Do not generate flow cover cuts IloCplex FlowCovers 0 Automatically determined mip cuts flowcuts 1 Generate flow cover cuts moderately 2 Generate flow cover cuts aggressively Default 0 Description MIP flow cover cuts indicator Determines whether or not to generate flow cover cuts for the problem Setting the value to 0 the default indicates that the attempt to generate flow cover cuts should continue only if it seems to be helping 20 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_FLOWPATHS 2051 01 1 Do not generate flow path cuts IloCplex FlowPaths 0 Automatically determined mip cuts pathcut 1 Generate flow path cuts moderately 2 Generate flow path cuts aggressively Default 0 Description MIP flow path cut indicator Determines whether or not flow path cuts should be generated for the problem Setting the value to 0 the default indicates that the attempt to generate flow path cuts should continue only if it seems to be helping CPX_PARAM_FRACCAND 2048 1 Any positive integer IloCplex FracCand mip limits gomorycand Default 200 Description Candidate limit for generating Gomory fractional cuts Limits the number of candidate variables for generating Gomory fractional cuts CPX PARAM FRACCUTS 2049 1 1 Do not generate Gomory fractional cuts IloCplex FracCuts 0 Automatically determined mip cuts gomory
24. ISInd22 ImplBd 22 IntSolLim 23 ItLim 23 MIPDisplay 24 MIPEmphasis 24 MIPInterval 25 MIPOrdInd 25 MIPOrdType 25 MIPStart 25 PARAMETERS 43 INDEX IPThreads 25 IRCuts 26 NetDisplay 26 etEpOpt 26 NetEpRHS 26 etFind 27 Net ItLim 27 etPPriInd 27 NodeAlg 37 NodeFileInd 27 NodeLim 28 NodeSel 28 NzGrowth 28 NzReadLim 28 ObjDif 29 Ob jLLim 29 ObjULim 29 29 PerLim 29 PPriInd 30 PreCompress 30 PreDual 30 PreInd 30 PrePass 31 PreslvNd 31 PriceLim 31 Probe 32 QPmakePSDInd 32 OPNzGrowth 32 OPNzReadLim 33 Reduce 33 ReInv 33 RelaxPreInd 33 RelObjpit 33 34 RINSHeur 34 RootAlg 23 32 36 RowGrowth 34 RowReadLim 34 ScaInd 34 SiftAlg 35 SiftDisplay 35 SiftItLim35 SimDisplay 35 SingLim 36 44 ILOG CPLEX 9 0 StrongCandLim 36 StrongItLim 36 StrongThreadLim 37 SubMIPNodeLim 37 Symmetry 37 Threads 37 TiLim 38 TreLim 38 VarSel 39 WorkDir 39 WorkMem 39 40 concurrent as algorithm for linear optimization 23 as MIP starting LP algorithm 36 Interactive Optimizer advance 9 barrier algorithm10 barrier colnonzeros 10 barrier convergetol 11 barrier crossover 10 barrier display 10 barrier limits corrections 11 barrier limits growth 11 barrier limits iterations 11 barrier limits objrange 12 barrier limits threads 13 barrier ordering 12 barrier outofcore 12 barrier startalg 13 clocktype 15 lpmethod 23 mip cuts cliques 1
25. L Partial pricing network pricing 2 CPXNET PRICE MULT PART Multiple partial pricing 3 CPXNET PRICE SORT MULT PART Multiple partial pricing with sorting Default 0 Description Network Simplex pricing algorithm The default 0 shows best performance for most problems and currently is equivalent to 3 CPX PARAM NODEFILEIND 2016 1 0 No node file IloCplex NodeFileInd 1 Node file in memory and compressed mip strategy file 2 Node file on disk 3 Node file on disk and compressed Default 1 Description Node storage file indicator Used when working memory WORKMEM has been exceeded by the size of the tree If the node file parameter is set to zero when the tree memory limit is reached optimization is terminated Otherwise a group of nodes is removed from the in memory set as needed By default CPLEX transfers nodes to node files when the in memory set is larger than 128 MBytes and it keeps the resulting node files in compressed form in memory At settings 2 and 3 the node files are transferred to disk in compressed and uncompressed form respectively into a directory named by the WORKDIR parameter and CPLEX actively manages which nodes remain in memory for processing The use of node files is described in more detail the ILOG CPLEX User s Manual ILOG CPLEX 9 0 PARAMETERS 27 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants
26. _REVERSEIND int 0 _ Off do not reverse bytes 1 CPX On reverse bytes IloCplex ReverseInd read reverse Default 0 Description SAV file reading byte reverse indicator If set to 1 reverses the byte ordering when reading SAV files This is useful when a SAV file was created on one system but is to be read on another system which uses a different byte ordering convention for example PCs versus many UNIX systems CPX PARAM RINSHEUR 2061 int 1 None IloCplex RINSHeur 0 Automatic default mip strategy rinsheur or any positive integer Default 0 Description Relaxation induced neighborhood search heuristic determines how often to apply the relaxation induced neighborhood search heuristic RINS heuristic Setting the value to 1 turns off the RINS heuristic Setting the value to 0 the default applies the RINS heuristic at an interval chosen automatically by CPLEX Setting the value to a positive number applies the RINS heuristic at the requested node interval For example setting RINSHeur to 20 dictates that the RINS heuristic be called at node 0 20 40 60 etc CPX PARAM ROWGROWTH 1046 Jint Any integer from 0 to 268 435 450 IloCplex RowGrowth read constraints Default 100 Description Constraint row memory growth Sets the growth policy for subsequent modifications of the problem CPX PARAM ROWREADLIM 1021 int Any integer from 0 to 268 435 450 IloCple
27. acking but does not force it CPLEX may choose to continue searching a limb of the tree if it seems a promising candidate for finding an integer feasible solution 14 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_CLIQUES 2003 int 1 Do not generate clique cuts IloCplex Cliques 0 Automatically determined mip cuts cliques 1 Generate clique cuts moderately 2 Generate clique cuts aggressively Default 0 Description MIP cliques indicator Determines whether or not clique cuts should be generated for the problem Setting the value to 0 the default indicates that the attempt to generate cliques should continue only if it seems to be helping CPX PARAM CLOCKTYPE 1006 int 1 CPU time IloCplex ClockType 2 Wall clock time total physical time elapsed clocktype Default 1 Description Computation time reporting Determines how computation times are measured on UNIX platforms Computation time on Windows systems is always measured as wall clock time Small variations in measured time on identical runs may be expected on any computer system under either setting of this parameter CPX PARAM COEREDIND 2004 0 Do not use coefficient reduction IloCplex CoeRedInd 1 Reduce only to integral coefficients preprocessing coeffreduce 2 Reduce all potential coefficients Default 2 Description Coefficient reduction se
28. are defined as final static objects in nested classes called IloCplex BooleanParam IloCplex IntParam IloCplex DoubleParam and IloCplex StringParam for Boolean integer floating point and string parameters respectively The parameter object names use mixed lower and upper case letters and must be prefixed with the appropriate class for scope For example 11o0Cplex IntParam ItLimis the object representing the parameter CPX PARAM ITLIM For Cf NET applications using Concert Technology the parameters follow the usual conventions for capitalizing attributes and defining scope ILOG CPLEX 9 0 PARAMETERS An integer that serves as a reference number for each parameter is shown in the table That integer reference number corresponds to the value that each symbolic constant represents as found in cplex h header file but it is strongly recommended that the symbolic constants be used instead of their integer equivalents whenever possible for the sake of portability to future versions of ILOG CPLEX Correspondence of Parameters Some parameters available for the Callable Library are not supported as parameters for IloCplex In particular Logging output is controlled by a parameter in the Callable Library CPX PARAM SCRIND but when using Concert Technology you control logging by configuring the output channel e IloCplex out in C e IloCplex out in Java e Cplex Out in C NET The parameters IloCplex RootAlg Il
29. ation preprocessing relax 1 CPX use presolve on initial relaxation Default 0 Description Relaxed LP presolve indicator Determines whether LP presolve is applied to the root relaxation in a mixed integer program Sometimes additional reductions can be made beyond any MIP presolve reductions that were already done CPX PARAM RELOBJDIF 2022 double Any number from 0 0 to 1 0 IloCplex RelObjDif mip tolerances relobjdifference Default 0 0 Description Relative objective difference cutoff Used to update the cutoff each time a mixed integer solution is found The value is multiplied by the absolute value of the integer objective and subtracted from added to the newly found integer objective when minimizing maximizing This forces the mixed integer optimization to ignore integer solutions that are not at least this amount better than the one found so far The relative objective difference parameter can be adjusted to improve problem solving efficiency by limiting the number of nodes however setting this parameter at a value other than zero the default can cause some integer solutions including the true integer optimum to be missed If both RELOBJDIFFERENCE and OBJDIFFERENCE are nonzero the value of OBJDIFFERENCE is used ILOG CPLEX 9 0 PARAMETERS 33 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM
30. ation You may also wish to lower this tolerance after finding an optimal solution if there is any doubt that the solution is truly optimal If the feasibility tolerance is set too low CPLEX may falsely conclude that a problem is infeasible If you encounter reports of infeasibility during Phase II of the optimization a small adjustment in the feasibility tolerance may improve performance 26 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX PARAM NETFIND 1022 1 CPX NETFIND PURE Extract pure network only IloCplex NetFind 2 CPX NETFIND REFLECT Try reflection scaling network netfind 3 NETFIND SCALE Try general scaling Default 2 Description Simplex network extraction level Establishes the level of network extraction for network simplex optimizations The default value is suitable for recognizing commonly used modeling approaches when representing a network problem within an LP formulation CPX PARAM NETITLIM 5001 int Any nonnegative integer IloCplex NetItLim network iterations Default BIGINT Description Network simplex iteration limit Sets the maximum number of iterations to be performed before the algorithm terminates without reaching optimality CPX PARAM NETPPRIIND 5004 int 0 CPXNET PRICE AUTO Automatic IloCplex NetPPriInd 1 PRICE PARTIA
31. difications of the problem CPX PARAM NZREADLIM 1024 int Any integer from 0 to 268 435 450 IloCplex NzReadLim read nonzeros Default Depends on the computer and operating system Description Nonzero element read limit Sets the number of nonzeros that can be read 28 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX PARAM OBJDIF 2019 double Any number IloCplex ObjDif mip tolerances objdifference Default 0 0 Description Absolute objective difference cutoff Used to update the cutoff each time a mixed integer solution is found This absolute value is subtracted from added to the newly found integer objective value when minimizing maximizing This forces the mixed integer optimization to ignore integer solutions that are not at least this amount better than the one found so far The OBJDIFFERENCE parameter can be adjusted to improve problem solving efficiency by limiting the number of nodes however setting this parameter at a value other than zero the default can cause some integer solutions including the true integer optimum to be missed Negative values for this parameter can result in some integer solutions that are worse than or the same as those previously generated but does not necessarily result in the generation of all possible integer solutions CPX PARAM OBJLLIM 1025 double Any number IloCplex ObjLLim simplex limits
32. ed from the tree A bbinterval of 0 means to never select the best bound node A bbinterval of 1 means always to select the best bound node and is thus equivalent to nodeselect 1 Higher values of bbinterval mean that the best bound node will be selected less frequently experience has shown it to be beneficial to occasionally select the best bound node and therefore the default bbinterval is 7 ILOG CPLEX 9 0 PARAMETERS 13 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX PARAM BNDSTRENIND int 1 Automatically determined IloCplex BndStrenInd 0 Do not apply bound strengthening preprocessing boundstrength 1 Apply bound strengthening Default 1 Description Bound strengthening indicator Used when solving mixed integer programs Bound strengthening tightens the bounds on variables perhaps to the point where the variable can be fixed and thus removed from consideration during branch amp cut This reduction is usually beneficial but occasionally due to its iterative nature takes a long time CPX PARAM BRDIR 2001 int 1 CPX BRDIR DOWN Down branch selected first IloCplex BrDir 0 CPX BRDIR AUTO Automatically determined mip strategy branch 1 CPX BRDIR UP Up branch selected first Default 0 Description MIP branching direction Used to decide which branch the up or the down branch should be taken first at each node CPX PARAM BTTOL 2002 double Any number from 0 0 to
33. efault CPLEX chooses automatically If the DUAL indicator is set to 1 the CPLEX presolve algorithm is applied to the primal problem but the resulting dual linear program is passed to the optimizer This is a useful technique for problems with more constraints than variables CPX PARAM PREIND int 0 orr Off do not use presolve IloCplex PreInd 1 CPX On use presolve preprocessing presolve Default 1 Description Presolve indicator When set to 1 invokes the CPLEX Presolve to simplify and reduce problems 30 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX PARAM PRELINEAR int 0 Only linear reductions IloCplex PreLinear 1 Full reductions preprocessing linear Default 1 Description Linear reduction indicator If only linear reductions are performed each variable in the original model can be expressed as a linear form of variables in the presolved model This guarantees for example that users can add their own custom cuts to the presolved model CPX PARAM PREPASS 1052 Jint 1 Determined automatically IloCplex PrePass 0 Do not use Presolve preprocessing numpass or any positive integer Default 1 Description Limit on the number of Presolve passes made When set to a nonzero value invokes the CPLEX Presolve to simplify and reduce problems When set to a positive value the Presolve is applied the specified
34. elected 1 CPX_VARSEL_MAXINFEAS Branch on variable with maximum infeasibility 2 CPX VARSEL PSEUDO Branch based on pseudo costs 3 CPX VARSEL STRONG Strong branching 4 CPX VARSEL PSEUDOREDUCED Branch based on pseudo reduced costs CPX PARAM VARSEL 2028 1 IloCplex VarSel mip strategy variableselect Default 0 Description MIP variable selection strategy Used to set the rule for selecting the branching variable at the node which has been selected for branching The maximum infeasibility rule chooses the variable with the largest fractional value the minimum infeasibility rule chooses the variable with the smallest fractional value The minimum infeasibility rule 1 may lead more quickly to a first integer feasible solution but is usually slower overall to reach the optimal integer solution The maximum infeasibility rule 1 forces larger changes earlier in the tree which tend to produce faster overall times to reach the optimal integer solution Pseudo cost 2 variable selection is derived from pseudo shadow prices Strong branching 3 causes variable selection based on partially solving a number of subproblems with tentative branches to see which branch is the most promising This strategy can be effective on large difficult MIP problems Pseudo reduced costs 4 are a computationally less intensive form of pseudo costs The default value 0 allows CPLEX to select the best rule
35. eset to a higher value when a problem is having difficulty maintaining feasibility during optimization You may also wish to lower this tolerance after finding an optimal solution if there is any doubt that the solution is truly optimal If the feasibility tolerance is set too low CPLEX may falsely conclude that a problem is infeasible If you encounter reports of infeasibility during Phase II of the optimization a small adjustment in the feasibility tolerance may improve performance CPX PARAM FINALFACTOR 1080 bool Off lloFalse IloCplex FinalFactor 1 CPX_ON On lloTrue simplex finalfactor Default On Description Final factor the indicator for basis final factorization after uncrush When preprocessing changes the model prior to optimization a reverse operation uncrush occurs at termination to restore the full model with its solution With default settings the simplex optimizers perform a final basis factorization on the full model before terminating If you turn off this parameter the final factorization after uncrushing will be skipped on large models this can save some time but computations that require a factored basis after optimization for example for the computation of the condition number Kappa may be unavailable depending on the operations performed during preprocessing If you run out of memory at the end of a simplex optimization consider turning off final factorization CPX PARAM FLOWCOV
36. etermines whether or not to generate MIR cuts for the problem Setting the value to 0 the default indicates that the attempt to generate MIR cuts should continue only if it seems to be helping CPX PARAM NETDISPLAY 5005 int 0 CPXNET NO DISPLAY OBJECTIVE No display IloCplex NetDisplay 1 CPXNET TRUE OBJECTIVE network display Display true objective values 2 CPXNET PENALIZE OBJECTIVE Display penalized objective values Default 2 Description Network logging display indicator Settings 1 and 2 differ only during Phase Setting 2 shows monotonic values whereas 1 usually does not CPX PARAM NETEPOPT 5002 double Any number from 1 11 to 1e IloCplex NetEpOpt network tolerances optimality Default 1 8 Description Optimality tolerance for CPXNETprimopt The optimality tolerance specifies the amount a reduced cost may violate the criterion for an optimal solution CPX PARAM NETEPRHS 5003 IloCplex NetEpRHS network tolerances feasibility double Any number from 1 11 to 1 Default 1 8 Description Feasibility tolerance for CPXNETprimopt The feasibility tolerance specifies the degree to which a problem s flow value may violate its bounds This tolerance influences the selection of an optimal basis and can be reset to a higher value when a problem is having difficulty maintaining feasibility during optimiz
37. f it seems to be helping CPX PARAM DIVETYPE 2060 1 0 automatic IloCplex DiveType 1 traditional dive mip strategy dive 2 probing dive 3 guided dive Default 0 Description MIP dive strategy The MIP traversal strategy occasionally performs probing dives where it looks ahead at both children nodes before deciding which node to choose The default automatic setting lets CPLEX choose when to perform a probing dive 1 directs CPLEX never to perform probing dives 2 always to probe 3 spend more time exploring potential solutions that are similar to the current incumbent Setting 2 always to probe is helpful for finding integer solutions CPX PARAM DPRIIND 1009 0 CPX_DPRIIND_AUTO Determined automatically IloCplex DPriInd 1 CPX_DPRIIND_FULL Standard dual pricing simplex dgradient 2 CPX_DPRIIND_STEEP Steepest edge pricing 3 CPX_DPRIIND_FULL_STEEP Steepest edge pricing in slack space 4 CPX_DPRIIND_STEEPQSTART Steepest edge pricing unit initial norms 5 CPX DPRIIND DEVEX devex pricing Default 0 Description Dual simplex pricing algorithm The default pricing 0 usually provides the fastest solution time but many problems benefit from alternate settings 18 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Value Symbolic Constants CPX_PARAM_EPAGAP 2008 double An
38. ficients LP Dual 1 Default starting basis Oor 1 Aggressive starting basis QP Primal 1 Slack basis 0 Ignore Q terms and use LP solver for crash 1 Ignore objective and use LP solver for crash QP Dual 1 Slack basis Oor1 Use Q terms for crash Description Simplex crash ordering Determines how CPLEX orders variables relative to the objective function when selecting an initial basis CPX PARAM CUTLO 2006 double Any number IloCplex CutLo mip tolerances lowercutoff Default 1e 79 Description Lower cutoff When the problem is a maximization problem the LOWERCUTOFF parameter is used to cut off any nodes that have an objective value below the lower cutoff value On a continued mixed integer optimization the larger of these values and the updated cutoff found during optimization are used during the next mixed integer optimization A too restrictive value for the LOWERCUTOFF parameter may result in no integer solutions being found CPX PARAM CUTPASS 2056 int 1 None IloCplex CutPass 0 Automatically determined mip limits cutpasses Positive values give number of passes to perform Default 0 Description Number of cutting plane passes Sets the upper limit on the number of passes CPLEX performs when generating cutting planes on a MIP model 16 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_CUTSFACTOR 2033 double Any n
39. for generating Gomory fractional cuts 21 candidate list 36 cliques indicator 15 constraint aggregation limit for cut generation 9 covers indicator 16 cutting plane passes 16 directory for working files 39 disjunctive cuts indicator 18 dive strategy 18 emphasis indicator 24 flow cover cuts indicator 20 flow path cut indicator 21 Gomory fractional cuts indicator 21 GUB cuts indicator 22 heuristic frequency 22 implied bound cuts indicator 22 integrality tolerance 19 mixed integer rounding MIR cut indicator 26 node log display information 24 node log interval 25 node selection strategy 28 number of cutting plane passes 16 parallel threads 37 pass limit for generating Gomory fractional cuts 21 preprocessing aggregator application limit 9 priority order generation 25 priority order indicator 25 relative mipgap tolerance 19 relaxation induced neighborhood search RINS heuristic 37 row multiplier factor for cuts 17 simplex iterations 36 solution limit 23 46 ILOG CPLEX 9 0 starting LP algorithm 36 starting values 25 strategy best bound interval 13 subnode limit 37 subproblem LP algorithm 37 subproblems and barrier 10 symmetry breaking cuts 37 thread limit 25 tolerances lower cutoff 16 tolerances upper cutoff 17 algorithm for root relaxation 32 indefiniteness indicator 32 N network as algorithm for continuous quadratic optimization 32 as algorithm for linear optimization 23 as MIP starting LP algorithm
40. ifting iterations Sets the maximum number of sifting iterations that may be performed if convergence to optimality has not been reached CPX PARAM SIMDISPLAY 1019 Jint 0 No iteration messages until solution IloCplex SimDisplay 1 Iteration info after each refactoring simplex display 2 Iteration info for each iteration Default 1 Description Simplex iteration display information Determines how often CPLEX reports during simplex optimization ILOG CPLEX 9 0 PARAMETERS 35 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_SINGLIM int Any nonnegative integer IloCplex SingLim simplex limits singularity Default 10 Description Simplex singularity repair limit Restricts the number of times CPLEX attempts to repair the basis when singularities are encountered Once this limit is exceeded CPLEX replaces the current basis with the best factorable basis that has been found CPX ALG AUTOMATIC Automatic CPX ALG PRIMAL Primal Simplex CPX ALG DUAL Dual Simplex CPX PARAM STARTALG 2025 IloCplex RootAlg mip strategy startalgorithm CPX ALG NET Network Simplex CPX ALG BARRIER Barrier CPX ALG SIFTING Sifting CPX_ALG_CONCURRENT Concurrent Dual arrier and Primal Wounhkhwn oOo Default 0 Description MIP starting LP algorithm Determines which LP algorithm should be used to solve the initial relaxation of the MIP
41. line The Callable Library issues a warning if the version recorded in the parameter file does not match the version of the product A warning is also issued of a non integral value is given for an integer valued parameter Here is an example of such a file CPLEX Parameter File Version 9 0 CPX_PARAM_EPPER 3 45000000000000e 06 CPX PARAM IISIND 1 CPX PARAM OBJULIM 1 23456789012345e 05 CPX PARAM PERIND 1 CPX_PARAM_SCRIND 1 CPX PARAM WORKDIR tmp The CPLEX parameters and their types options and default values are listed in the following table The Callable Library name for each parameter is listed first followed by the Concert Technology name followed by the name in the Interactive Optimizer Some CPLEX parameters are not used in the Concert Technology Library and in those cases no Concert Technology Library name appears ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX ADVIND 1001 int 0 Off do not use advanced start information IloCplex AdvInd 1 On CPLEX will use an advanced basis supplied by advance the user 2 On CPLEX will crush an advanced basis or starting vector supplied by the user Default 0 Description Advanced start indicator An indicator which if set to 1 or 2 uses advanced starting information when optimization is initiated Setting 2 may be effective for MIPs in which the percentage of integer constraints is low It may also
42. matic setting may be expanded in the future so that CPLEX chooses the algorithm based on additional problem characteristics CPX PARAM OPNZGROWTH 4002 int Any integer from 0 to 268 435 450 IloCplex OQPNzGrowth read qpnonzeros Default 200 Description QP Q matrix memory growth Sets the growth policy for subsequent modifications of the problem 32 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_QPNZREADLIM 4001 int TloCplex QPNzReadLim read qpnonzeros Any integer from 0 to 268 435 450 Default 500 Description QP Q matrix nonzero read limit Sets the number of Q matrix nonzeros that can be read CPX_PARAM_REDUCE 1057 Jint 0 primal and dual reductions TloCplex Reduce 1 Only primal reductions preprocessing reduce 2 Only dual reductions 3 Both primal and dual reductions Default 3 Description Primal and dual reduction type Determines whether primal reductions dual reductions or both are performed during preprocessing CPX_PARAM_REINV 1031 lint 0 Determined automatically IloCplex ReInv or any integer from 1 to 10 000 simplex refactor Default 0 Description Simplex refactoring frequency Sets the number of iterations between refactoring of the basis matrix CPX PARAM RELAXPREIND 2034 int 0 CPx_OFF Off do not use presolve on initial IloCplex RelaxPreInd relax
43. node where n is the setting of the MIP INTERVAL parameter A setting of 3 additionally generates an entry for every nth node giving the number of cuts added to the problem for the previous INTERVAL nodes A setting of 4 additionally generates entries for the LP root relaxation according to the set simplex display setting A setting of 5 additionally generates entries for the LP subproblems also according to the set simplex display setting CPX PARAM MIPEMPHASIS 2058 0 CPX MIPEMPHASIS BALANCED Balance IloCplex MIPEmphasis optimality and feasibility mip emphasis 1 CPX MIPEMPHASIS FEASIBILITY Emphasize feasibility over optimality 2 CPX MIPEMPHASIS OPTIMALITY Emphasize optimality over feasibility 3 CPX MIPEMPHASIS BESTBOUND Emphasize moving best bound 4 CPX MIPEMPHASIS HIDDENFEAS Emphasize hidden feasibility Default 0 Description MIP emphasis indicator With the default setting of BALANCED CPLEX works toward a rapid proof of an optimal solution but balances that with effort toward finding high quality feasible solutions early in the optimization When set to FEASIBILITY CPLEX frequently will generate more feasible solutions as it optimizes the problem at some sacrifice in the speed to the proof of optimality When set to OPTIMALITY less effort may be applied to finding feasible solutions early With the seting BESTBOUND even greater emphasis is placed on
44. ns the advanced start indicator off so that no internally stored advanced start is used It then attempts to find a file with a xxx extension in the working directory The name of the file preceding the xxx extension must match the name of the problem being optimized Value Symbolic Constants 0 CPx_OFF Off disable xxx file reading 1 cPx_on On enable xxx file reading Default 0 40 ILOG CPLEX 9 0 PARAMETERS A accessing parameters Callable Library CPXgetdblparam6 PXgetintparam6 PXgetstrparam6 PXinfodblparam6 PXinfointparam6 PXinfostrparam6 PXsetdblparam6 PXsetdefaults 6 PXsetintparam6 CPXsetstrparam6 Concert Technology getDefault 5 getMax 5 getMin5 getParam5 setDefaults 5 setParam5 C C C barrier algorithm 10 as algorithm for continuous quadratic optimization 32 as algorithm for linear optimization 23 as MIP starting LP algorithm 36 as MIP subproblem LP algorithm 37 ILOG CPLEX 9 0 Index as sifting subproblem algorithm 35 column nonzeros 10 convergence tolerance for LP and QP problems 11 convergence tolerance for QCP problems 12 crossover algorithm 10 directory for working files out of core 39 display information 10 global time limit 38 growth limit 11 iteration limit 11 maximum correction limit 11 objective range 12 ordering algorithm 12 out of core indicator 12 starting point algorithm 13 thread limit 13 Callable Lib
45. oCplex NodeAlg are used where parameters CPX_PARAM_STARTALG and CPX PARAM SUBALG would be used for the Callable Library Saving Parameter Settings to a File Itis possible to read and write a file of parameter settings with the Callable Library The file extension is prm The Callable Library routine CPXreadcopyparam reads parameter values from a file with pxm extension The routine CPXwriteparam writes a file of the current non default parameter settings to a file with the extension Here is the format of such a file CPLEX Parameter File Version number parameter name parameter value ILOG CPLEX reads the entire file before changing any of the parameter settings After successfully reading a parameter file the Callable Library first sets all parameters to their default value Then it applies the settings it read in the parameter file No changes are made if the parameter file contains errors such as missing or illegal values There is no checking for duplicate entries in the file In the case of duplicate entries the last setting in the file is applied ILOG CPLEX 9 0 PARAMETERS 7 PARAMETER TABLE Parameter Table When you write a parameter file from the Callable Library only the non default values are written to the file String values may be double quoted or not but are always written with double quotation marks The comment character in a parameter file is ILOG CPLEX ignores the rest of the
46. of 0 automatic can result in dramatic reductions or dramatic increases in solution time depending on the model CPX_PARAM_QPMAKEPSDIND int 0 CPX_OFF Off IloCplex QPmakePSDInd 1 CPX ON On preprocessing qpmakepsd Default On Description Indefinite MIQP indicator Determines whether CPLEX will attempt to adjust a MIQP formulation in which all the variables appearing in the quadratic term are binary When this feature is active adjustments will be made to the elements of a quadratic matrix that is not nominally positive semi definite PSD as required by CPLEX for all QP formulations to make it PSD and will also attempt to tighten an already PSD matrix for better numerical behavior The default setting of 1 means yes but you can turn it off if necessary most models should benefit from the default setting PARAM 1063 int CPX_ALG_AUTOMATIC Automatic IloCplex RootAlg 1 CPX ALG PRIMAL Primal Simplex qpmethod 2 CPX ALG DUAL Dual Simplex 3 CPX ALG NET Network Simplex 4 CPX ALG BARRIER Barrier Default 0 Description Algorithm for continuous quadratic optimization Determines which algorithm is used when CPXqpopt or optimize the Interactive Optimizer is invoked Currently the behavior of the Automatic setting is that CPLEX invokes the barrier optimizer for continuous QP models and the dual simplex optimizer for root relaxations of MIQP models The Auto
47. onnegative number IloCplex CutsFactor mip limits cutsfactor Default 4 0 Description Row multiplier factor for cuts Limits the number of cuts that can be added The number of rows in the problem with cuts added is limited to CUTSFACTOR times the original number of rows If the problem is presolved the original number of rows is that from the presolved problem A CUTSFACTOR of 1 0 or less means that no cuts will be generated Because cuts can be added and removed during the course of optimization CUTSFACTOR may not correspond directly to the number of cuts seen during the node log or in the summary table at the end of optimization CPX PARAM CUTUP 2007 double Any number IloCplex CutUp mip tolerances uppercutoff Default 1 72 Description Upper cutoff Cuts off any nodes that have an objective value above the upper cutoff value when the problem is a minimization problem When a mixed integer optimization problem is continued the smaller of these values and the updated cutoff found during optimization are used during the next mixed integer optimization A too restrictive value for the UPPERCUTOFF parameter may result in no integer solutions being found CPX PARAM DATACHECK 1056 int 0 CPX OFF Off do not check IloCplex DataCheck 1 CPX oN On check read datacheck Default 0 Description Data consistency checking indicator When set to ON the CPXread and CPXchg functions perfo
48. ormal setup and iteration information barrier display 2 Diagnostic information Default 1 Description Barrier display information Determines the level of barrier progress information to be displayed 10 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX PARAM BAREPCOMP 3002 double Any positive number gt 1 12 IloCplex BarEpComp barrier convergetol Default 1e Description Convergence tolerance for LP and QP problems For problems with quadratic constraints QCP see PARAM BARQCPEPCOME Sets the tolerance on complementarity for convergence The barrier algorithm terminates with an optimal solution if the relative complementarity is smaller than this value Changing this tolerance to a smaller value may result in greater numerical precision of the solution but also increases the chance of a convergence failure in the algorithm and consequently may result in no solution at all Therefore caution is advised in deviating from the default setting CPX PARAM BARGROWTH 3003 double 1 0 or greater IloCplex BarGrowth barrier limits growth Default 1e Description Barrier growth limit Used to detect unbounded optimal faces At higher values the barrier algorithm is less likely to conclude that the problem has an unbounded optimal face but more likely to have numerical difficulties if the problem has an unbounded face CPX P
49. preprocessing coeffreduce 15 preprocessing compress 30 preprocessing dependency 17 preprocessing dual 30 preprocessing fill9 preprocessing linear 31 preprocessing numpass 31 preprocessing presolve 30 preprocessing qpmakepsd 32 preprocessing reduce 33 preprocessing relax 33 preprocessing symmetry 37 qpmethod 32 constraints 34 datacheck 17 nonzeros 28 qpnonzeros 32 33 reverse 34 scale 34 variables 15 read read read read read read read set bar sifting sifting sifting simp simpl simpl simpl simpl simpl simpl simpl simpl simpl simpl simpl simpl simpl simpl simpl simpl simpl simpl qcpconvergetol 12 algorithm 35 display 35 iterations 35 basisinterval 13 crash 16 dgradient 18 display 35 finalfactor 20 iisfind 22 limits iterations 23 limits lowerobj 29 limits perturbation 29 limits singularity 36 limits upperob 3 29 perturbation 20 29 pgradient 30 pricing 31 refactor 33 tolerances feasibility 20 tolerances markowitz 19 tolerances optimality 19 xxxstart 40 threads 37 PARAMETERS 45 INDEX workdir 39 workmem 39 MIP absolute mipgap tolerance 19 absolute objective difference cutoff 29 advanced starting indicator 9 backtracking tolerance 14 barrier in infeasibility start 10 branching direction 14 candidate limit
50. proving optimality through moving the best bound value so that the detection of feasible solutions along the way becomes almost incidental When set to HIDDENFEAS the MIP optimizer works hard to find high quality feasible solutions that are otherwise very difficult to find so consider this setting when the FEASIBILITY emphasis has difficulty finding solutions of acceptable quality 24 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX MIPINTERVAL 2013 0 IloCplex MIPInterval mip interval Any positive integer Default 100 Description MIP node log interval Controls the frequency of node logging when CPX MIPDISPLAY is set higher than 1 CPX PARAM MIPORDIND 2020 1 IloCplex MIPOrdInd mip strategy order 0 CPx_OFF Off do not use order information 1 CPX oN On use order information if it exists Default 1 Description MIP priority order indicator When set to on uses the priority order if it exists for the next mixed integer optimization CPX PARAM MIPORDTYPE 2032 IloCplex MIPOrdType mip ordertype 0 Do not generate a priority order 1 CPX_MIPORDER_COST Use decreasing cost 2 CPX MIPORDER BOUNDS Use increasing bound range 3 CPX MIPORDER SCALEDCOST Use increasing cost per coefficient count Default 0 Description MIP priority order genera
51. rary CPX PARAM ADVIND 9 CPX PARAM AGGCUTLIM 9 CPX PARAM AGGFILL9 CPX PARAM AGGIND 9 CPX PARAM BARALG 10 CPX PARAM BARCOLNZ 10 CPX PARAM BARCROSSALG 10 CPX PARAM BARDISPLAY 10 CPX PARAM BAREPCOMP 11 CPX PARAM BARGROWTH 11 PARAMETERS 41 INDEX PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA PX PARA CA OOO CX QM Y OO OO An OQ 0150620 Ce Q0 QO Ok Qi 06i OOo A PX PARAM BARITLIM 11 BARMAXCOR 11 BAROBURNG 12 BAROOC 12 BARORDER 12 BARQCPEPCOMP 12 BARSTARTALG 13 BARTHREADS 13 BASINTERVAL 13 BBINTERVAL 13 BNDSTRENIND 14 BRDIR1 BTTOL 14 CLIQUES 15 CLOCKTYPE 15 COEREDIND 15 COLGROWTH 15 READLIM 15 COVERS 16 I fl pi BE UTSFACTOR 17 UTUP 17 ACHECK 17 EPIND 17 ISJCUTS 18 IVETYPE 18 PRIIND 18 PAGAP 19 PGAP 19 PINT 19 PMRK 19 POPT 19 EPPER 20 EPRHS 20 FINALFACTOR 20 FLOWCOVERS 20 FLOWPATHS 21 FRACCAND 21 FRACCUTS 21 FRACPASS 21 EUIS
52. rm extensive checking on data in the array arguments such as checking that indices are within range that there are no duplicate entries and that values are valid for the type of data or are valid numbers This is useful for debugging applications 1 automatic let CPLEX choose when to use dependency checking Off do not use dependency checker 1 turn on only at the beginning of preprocessing 2 turn on only at the end of preprocessing 3 turn on at the beginning and at the end of preprocessing Default 0 nt CPX PARAM DEPIND 1008 IloCplex DepInd preprocessing dependency Description Dependency indicator Determines whether to activate the dependency checker If on the dependency checker searches for dependent rows during preprocessing If off dependent rows are not identified ILOG CPLEX 9 0 PARAMETERS 17 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX PARAM DISJCUTS 2053 Jint 1 Do not generate disjunctive cuts IloCplex DisjCuts 0 Automatically determined mip cuts disjunctive 1 Generate disjunctive cuts moderately 2 Generate disjunctive cuts aggressively 3 Generate disjunctive cuts very aggressively Default 0 Description MIP disjunctive cuts indicator Determines whether or not disjunctive cuts should be generated for the problem Setting the value to 0 the default indicates that the attempt to generate disjunctive cuts should continue only i
53. ss and set parameters with the following routines CPXgetdblparam Accesses a parameter of type double CPXsetdblparam Changes a parameter of type double CPXinfodblparam Gets the default value and range of a parameter of type double CPXgetintparam Accesses a parameter of type integer CPXsetintparam Changes a parameter of type integer CPXinfointparam Gets the default value and range of a parameter of type integer CPXgetstrparam Accesses a parameter of type string CPXsetstrparam Changes a parameter of type string CPXinfostrparam Gets the default value of a parameter of type string CPXsetdefaults Resets all parameters to their standard default values Parameter Names In the parameter table each parameter has a name that is a symbolic constant to refer to it within a program For the Callable Library these constants are capitalized and start with CPX for example CPX PARAM ITLIM They are used as the second argument in all parameter routines except CPXsetdefaults which does not require them For C applications using Concert Technology the parameters are defined in nested enumeration types for Boolean integer floating point and string parameters The enum names use mixed lower and upper case letters and must be prefixed with the class name IloCplex for scope For example IloCplex ItLim is the I1oCplex equivalent Of CPX PARAM ITLIM For Java applications using Concert Technology the parameters
54. tAlg 2 Estimate dual barrier startalg 3 Average of primal estimate dual 0 4 Average of primal estimate estimate dual Default 1 Description Barrier starting point algorithm Sets the algorithm to be used to compute the initial starting point for the barrier optimizer CPX_PARAM_BARTHREADS 3016 int 0 Determined by global thread default IloCplex BarThreads gt 0 upper limit on threads for Parallel Barrier barrier limits threads Default 0 Description Barrier thread limit Determines the maximum number of parallel processes threads that will be invoked by the parallel barrier optimizer The default value of 0 means that the limit will be determined by the value of CPX PARAM THREADS the global thread limit parameter A positive value will override the value found in THREADS CPX PARAM BASINTERVAL 1004 int Any positive integer IloCplex BasInterval simplex basisinterval Default BIGINT Description Basis file saving frequency Establishes the number of iterations between writes of the CPLEX backup simplex basis file in xxx format CPX PARAM BBINTERVAL 2039 int 0 Best estimate node always selected IloCplex BBInterval or any positive integer mip strategy bbinterval Default 7 Description MIP strategy best bound interval When you set nodeselect 2 the bbinterval is the interval at which the best bound node instead of the best estimate node is select
55. tion Used to select the type of generic priority order to generate when no priority order is present CPX PARAM MIPSTART 2035 int 0 cPx not use starting values IloCplex MIPStart 1 CPX Use starting values at node 0 mip strategy mipstart Default 0 Description Indicator for starting MIP values Used to indicate how the MIP advanced starting values are used A setting of 1 indicates that the values should be checked to see if they provide an integer feasible solution before starting optimization CPX PARAM MIPTHREADS 2014 1 0 determined by global thread default IloCplex MIPThreads gt 0 upper limit on threads for Parallel MIP mip limits threads Default 0 Description MIP thread limit Determines the maximum number of parallel processes threads that will be invoked by the Parallel MIP optimizer The default value of 0 means that the limit will be determined by the value of PARAM THREADS the global thread limit parameter A positive value will override the value found in PARAM THREADS ILOG CPLEX 9 0 PARAMETERS 25 PARAMETER TABLE Parameter Name Code Value Symbolic Constants CPX PARAM MIRCUTS 2052 int 1 Do not generate MIR cuts IloCplex MIRCuts 0 Automatically determined mip cuts mircut 1 Generate MIR cuts moderately 2 Generate MIR cuts aggressively Default 0 Description MIP MIR mixed integer rounding cut indicator D
56. tolerance 19 perturbation constant 20 perturbation indicator 29 perturbation limit 29 pgradient indicator 30 pricing candidate list size 31 primal pricing algorithm 30 refactoring frequency 33 singularity repair limit 36 ILOG CPLEX 9 0 upper objective value limit 29 PARAMETERS INDEX 47 INDEX 48 ILOG CPLEX 9 0 PARAMETERS
57. toring Disk use is controlled by the parameters CPX_PARAM_WORKMEM and CPX_PARAM_WORKDIR CPX PARAM BARORDER 3014 int 0 Automatic IloCplex BarOrder 1 Approximate minimum degree AMD barrier ordering 2 Approximate minimum fill AMF 3 Nested dissection ND Default 0 Description Barrier ordering algorithm Sets the algorithm to be used to permute the rows of the constraint matrix in order to reduce fill in the Cholesky factor CPX_PARAM_BARQCPEPCOMP 3020 double Any positive number gt 1 12 IloCplex BarQCPEpComp set bar qcpconvergetol Default 1 8 Description Convergence tolerance for QCP problems That is for quadratically constrained problems For LPs and for QPs that is when all the constraints are linear see Sets the tolerance on complementarity for convergence The barrier algorithm terminates with an optimal solution if the relative complementarity is smaller than this value Changing this tolerance to a smaller value may result in greater numerical precision of the solution but also increases the chance of a convergence failure in the algorithm and consequently may result in no solution at all Therefore caution is advised in deviating from the default setting 12 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX PARAM BARSTARTALG 3017 int 1 Dual is 0 IloCplex BarStar
58. tting Determines how coefficient reduction is used Coefficient reduction improves the objective value of the initial and subsequent LP relaxations solved during branch amp cut by reducing the number of non integral vertices CPX PARAM COLGROWTH int Any integer from 0 to 268 435 450 IloCplex ColGrowth read variables Default 100 Description Variable column memory growth Sets the extra space allocated for subsequent modifications of the problem CPX PARAM COLREADLIM 1023 Jint Any integer from 0 to 268 435 450 IloCplex ColReadLim read variables Default Depends on the computer and operating system Description Variable column read limit Sets the number of variables that can be read ILOG CPLEX 9 0 PARAMETERS 15 PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_COVERS 2005 int 1 Do not generate cover cuts IloCplex Covers 0 Automatically determined mip cuts covers 1 Generate cover cuts moderately 2 Generate cover cuts aggressively Default 0 Description MIP covers indicator Determines whether or not cover cuts should be generated for the problem Setting the value to 0 the default indicates that the attempt to generate covers should continue only if it seems to be helping CPX PARAM CRAIND 1007 Jint LP Primal IloCplex CraInd 0 Ignore objective coefficients during crash simplex crash 1or1 Alternate ways of using objective coef
59. x RowReadLim read constraints Default Depends on the computer and operating system Description Constraint row read limit Sets the number of constraints that can be read CPX PARAM SCAIND 1034 1 No scaling IloCplex ScaInd 0 Equilibration scaling read scale 1 More aggressive scaling Default 0 Description Scale parameter Indicates how to scale the problem matrix 34 ILOG CPLEX 9 0 PARAMETERS PARAMETER TABLE Parameter Name Code Type Value Symbolic Constants CPX_PARAM_SCRIND int 0 Off 1 CPX On Default 0 Description Messages to screen indicator Indicates whether or not results messages are displayed on screen 0 Automatic 1 Primal simplex 2 Dual simplex 3 Network simplex 4 Barrier CPX PARAM SIFTALG 1077 IloCplex SiftAlg sifting algorithm Default 0 Description Sifting subproblem algorithm Sets the algorithm to be used for solving sifting subproblems CPX PARAM SIFTDISPLAY 1076 0 No display IloCplex SiftDisplay 1 Display major iterations sifting display 2 Display LP subproblem information within each sifting iteration Default 1 Description Sifting display information Determines the amount of sifting progress information to be displayed CPX PARAM SIFTITLIM 1078 Any nonnegative integer IloCplex SiftItLim sifting iterations Default BIGINT Description Upper limit on s
60. y nonnegative number IloCplex EpAGap mip tolerances absmipgap Default 1 06 Description Absolute mipgap tolerance Sets an absolute tolerance on the gap between the best integer objective and the objective of the best node remaining When this difference falls below the value of the ABSMIPGAP parameter the mixed integer optimization is stopped CPX PARAM EPGAP 2009 double Any number from 0 0 to 1 0 IloCplex EpGap mip tolerances mipgap Default 1 04 Description Relative mipgap tolerance Sets a relative tolerance on the gap between the best integer objective and the objective of the best node remaining When the value bestnode bestinteger le 10 bestinteger falls below the value of the MIPGAP parameter the mixed integer optimization is stopped For example to instruct CPLEX to stop as soon as it has found a feasible integer solution proved to be within five percent of optimal set the relative mipgap tolerance to 05 CPX PARAM EPINT 2010 double Any number from 0 0 to 1 0 IloCplex EpInt mip tolerances integrality Default 1 92 Description Integrality tolerance Specifies the amount by which an integer variable can be different from an integer and still be considered feasible A value of zero is permitted and the optimizer will attempt to meet this tolerance However in some models computer roundoff may still result in small nonzero deviations from integrality CPX PARAM

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