CBC Options#
ampl: option solver cbc; # change the solver
ampl: option cbc_options 'option1=value1 option2=value2'; # specify options
ampl: solve; # solve the problem
Solver options obtained with $ cbc -=.
CBC Optimizer Options for AMPL
--------------------------------------------
To set these options, assign a string specifying their values to the AMPL
option "cbc_options". For example:
ampl: option cbc_options 'presolve=more';
'' Options:
:cplexUse (cplexUse)
Whether to use Cplex!
off - Turn off
on - Turn on
:mixedIntegerRoundingCuts (mixedIntegerRoundingCuts)
Whether to use Mixed Integer Rounding cuts
off - disabled
on - enabled
root - enabled only on root node
ifmove - enabled in the tree if it moves the objective value
forceOn - enabled at every node
onglobal -
acc:_all
Solver acceptance level for all constraints and expressions. Value
meaning: as described in the specific acc:... options.
Can be useful to disable all reformulations (acc:_all=2), or force
linearization (acc:_all=0.)
acc:lineq
Solver acceptance level for 'LinConEQ' as flat constraint, default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:linge
Solver acceptance level for 'LinConGE' as flat constraint, default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:linle
Solver acceptance level for 'LinConLE' as flat constraint, default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:linrange (acc:linrng)
Solver acceptance level for 'LinConRange' as flat constraint, default 2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:sos1
Solver acceptance level for 'SOS1Constraint' as flat constraint, default
2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
acc:sos2
Solver acceptance level for 'SOS2Constraint' as flat constraint, default
2:
0 - Not accepted natively, automatic redefinition will be attempted
1 - Accepted but automatic redefinition will be used where possible
2 - Accepted natively and preferred
alg:basis (basis)
Whether to use or return a basis:
0 - No
1 - Use incoming basis (if provided)
2 - Return final basis
3 - Both (1 + 2 = default)
alg:perturbation (perturbation)
Whether to perturb the problem
off - Turn off
on - Turn on
alg:relax (relax)
0*/1: Whether to relax integrality of variables.
alg:start (warmstart)
Whether to use incoming primal (and dual, for LP) variable values in a
warmstart:
0 - No
1 - Yes (for LP: if there is no incoming alg:basis) (default)
2 - Yes (for LP: ignoring the incoming alg:basis, if any.)
bar:bscale (bscale)
Whether to scale in barrier (and ordering speed)
off -
on -
off1 -
on1 -
off2 -
on2 -
bar:cholesky (cholesky)
Which cholesky algorithm
native -
dense -
fudgeLong_dummy -
wssmp_dummy -
UniversityOfFlorida_dummy -
Taucs_dummy -
Mumps_dummy -
Pardiso_dummy -
bar:crash (crash)
Whether to create basis for problem
off - Turn off
on - Turn on
bar:crossover (crossover)
Whether to get a basic solution with the simplex algorithm after the
barrier algorithm finished
on -
off -
maybe -
presolve -
bar:gammadelta (gamma(Delta))
Whether to regularize barrier
off -
on -
gamma -
delta -
onstrong -
gammastrong -
deltastrong -
bar:kkt (KKT)
Whether to use KKT factorization in barrier
off - Turn off
on - Turn on
cut:cliqueCuts (cliqueCuts)
Whether to use Clique cuts
off - disabled
on - enabled
root - enabled only on root node
ifmove - enabled in the tree if it moves the objective value
forceOn - enabled at every node
onglobal -
cut:cut (cutsOnOff)
Switches all cut generators on or off
off - disabled
on - enabled
root - enabled only on root node
ifmove - enabled in the tree if it moves the objective value
forceOn - enabled at every node
cut:flowcovercuts (flowCoverCuts)
Whether to use Flow Cover cuts
off - disabled
on - enabled
root - enabled only on root node
ifmove - enabled in the tree if it moves the objective value
forceOn - enabled at every node
onglobal -
cut:gmicuts (GMICuts)
Whether to use alternative Gomory cuts
off -
on -
root -
ifmove -
forceOn -
endonly -
long -
longroot -
longifmove -
forceLongOn -
longendonly -
cut:gomorycuts (gomoryCuts)
Whether to use Gomory cuts
off -
on -
root -
ifmove -
forceOn -
onglobal -
forceandglobal -
forceLongOn -
long -
cut:knapsackcuts (knapsackCuts)
Whether to use Knapsack cuts
off -
on -
root -
ifmove -
forceOn -
onglobal -
forceandglobal -
cut:lagomorycuts (lagomoryCuts)
Whether to use Lagrangean Gomory cuts
off -
endonlyroot -
endcleanroot -
root -
endonly -
endclean -
endboth -
onlyaswell -
cleanaswell -
bothaswell -
onlyinstead -
cleaninstead -
bothinstead -
onlyaswellroot -
cleanaswellroot -
bothaswellroot -
cut:latwomircuts (latwomirCuts)
Whether to use Lagrangean TwoMir cuts
off -
endonlyroot -
endcleanroot -
endbothroot -
endonly -
endclean -
endboth -
onlyaswell -
cleanaswell -
bothaswell -
onlyinstead -
cleaninstead -
bothinstead -
cut:liftandprojectcuts (liftAndProjectCuts)
Whether to use Lift and Project cuts
off - disabled
on - enabled
root - enabled only on root node
ifmove - enabled in the tree if it moves the objective value
forceOn - enabled at every node
cut:probingCuts (probingCuts)
Whether to use Probing cuts
off -
on -
root -
ifmove -
forceOn -
onglobal -
forceonglobal -
forceOnBut -
forceOnStrong -
forceOnButStrong -
strongRoot -
cut:reduce2andsplitcts (reduce2AndSplitCuts)
Whether to use Reduce-and-Split cuts - style 2
off -
on -
root -
longOn -
longRoot -
cut:reduceandsplitcuts (reduceAndSplitCuts)
Whether to use Reduce-and-Split cuts
off - disabled
on - enabled
root - enabled only on root node
ifmove - enabled in the tree if it moves the objective value
forceOn - enabled at every node
cut:residualcapacitycuts (residualCapacityCuts)
Whether to use Residual Capacity cuts
off - disabled
on - enabled
root - enabled only on root node
ifmove - enabled in the tree if it moves the objective value
forceOn - enabled at every node
cut:twomircuts (twoMirCuts)
Whether to use Two phase Mixed Integer Rounding cuts
off -
on -
root -
ifmove -
forceOn -
onglobal -
forceandglobal -
forceLongOn -
cut:zeroHalfCuts (zeroHalfCuts)
Whether to use zero half cuts
off - disabled
on - enabled
root - enabled only on root node
ifmove - enabled in the tree if it moves the objective value
forceOn - enabled at every node
onglobal -
cvt:bigM (cvt:bigm, cvt:mip:bigM, cvt:mip:bigm)
Default value of big-M for linearization of logical constraints. Not
used by default. Use with care (prefer tight bounds). Should be smaller
than (1.0 / [integrality tolerance])
cvt:dvelim (dvelim)
Eliminate AMPL defined variables by substitution into linear, quadratic,
and polynomial expressions:
0 - Do not eliminate, always instantiate the variables.
1 - Eliminate only those used 1x. This can increase model density but
greatly simplifies some models.
2 - Always substitute where possible, even if the variable needs to be
instantiated for use in other places. Can introduce redundancy, but
seems best for some models (default.)
See also AMPL options linelim and substout.
cvt:expcones (expcones)
0*/1: Recognize exponential cones.
cvt:mip:eps (cvt:cmp:eps, cmp:eps)
Tolerance for strict comparison of continuous variables for MIP. Applies
to <, >, and != operators. Also applies to negation of conditional
comparisons: b==1 <==> x<=5 means that with b==0, x>=5+eps. Default:
1e-4.
cvt:multoutcard (multoutcard)
Up to which (estimated) QP matrix cardinality should a product of 2
linear expressions be multiplied out. Default 1e9.
Can speed up model input, but prone to numerical issues.
cvt:names (names, modelnames)
Whether to read or generate variable / constraint / objective names:
0 - No names
1 - (Default) Only provide names if at least one of .col / .row name
files was written by AMPL (AMPL: `option [<solver>_]auxfiles rc;`)
2 - Read names from AMPL, but create generic names if not provided
3 - Create generic names.
cvt:plapprox:domain (plapprox:domain, plapproxdomain)
For piecewise-linear approximated functions, both arguments and result
are bounded to +-[pladomain]. Default 1e6.
cvt:plapprox:reltol (plapprox:reltol, plapproxreltol)
Relative tolerance for piecewise-linear approximation. Default 0.01.
cvt:pre:all
0/1*: Set to 0 to disable most presolve in the flat converter.
cvt:pre:eqbinary
0/1*: Preprocess reified equality comparison with a binary variable.
cvt:pre:eqresult
0/1*: Preprocess reified equality comparison's decidable cases.
cvt:pre:ineqresult
0/1*: Preprocess reified inequality comparison's decidable cases.
cvt:pre:ineqrhs
0/1*: Preprocess reified inequality comparison's right-hand sides.
cvt:pre:unnest
0/1*: Inline nested expressions, currently Ands/Ors.
cvt:prod (cvt:pre:prod)
Product preprocessing flags. Sum of a subset of the following bits:
1 - Quadratize higher-order products in the following order: integer
terms first, then real-valued ones; in each group, smaller-range terms
first.
2 - Logicalize products of 2 binary terms. Logicalizing means that the
product is converted to a conjunction. If the solver does not support it
natively (see acc:and), the conjunction is linearized.
4 - Logicalize products of >=3 binary terms.
Default: 7.
Bits 2 or 4 imply bit 1.
cvt:qp2passes (cvt:qp2pass, qp2passes, qp2pass)
Parse sums of QP expressions in 2 passes. Usually faster. Default 1.
cvt:quadcon (passquadcon)
Convenience option. Set to 0 to disable quadratic constraints. Synonym
for acc:quad..=0. Currently this disables out-multiplication of
quadratic terms, then they are linearized.
cvt:quadobj (passquadobj)
0*/1: Pass quadratic objective terms to the solver. When 0, if the
solver accepts quadratic constraints, such a constraint will be created
with those, otherwise linearly approximated.
cvt:socp (socpmode, socp)
Second-Order Cone recognition mode:
0 - Do not recognize SOCP forms
1 - Recognize from non-quadratic expressions only (sqrt, abs)
2 - Recognize from quadratic and non-quadratic SOCP forms. Helpful if
the solver does not recognize non-standard forms
Recognized SOCP forms can be further converted to (SOCP-standardized)
quadratic constraints, see cvt:socp2qc. Default: 0.
cvt:socp2qc (socp2qcmode, socp2qc)
Mode to convert recognized SOCP forms to SOCP-standardized quadratic
constraints:
0 - Do not convert
1 - Convert if no other cone types found, and not all original
quadratics could be recognized as SOC, in particular if the
objective is quadratic
2 - Always convert
Such conversion can be necessary if the solver does not accept a mix of
conic and quadratic constraints/objectives. Default: 2.
cvt:sos (sos)
0/1*: Whether to honor declared suffixes .sosno and .ref describing SOS
sets. Each distinct nonzero .sosno value designates an SOS set, of type
1 for positive .sosno values and of type 2 for negative values. The .ref
suffix contains corresponding reference values used to order the
variables.
cvt:sos2 (sos2)
0*/1: Whether to honor SOS2 constraints for nonconvex piecewise-linear
terms, using suffixes .sos and .sosref provided by AMPL. Currently under
rework.
cvt:uenc:negctx:max (uenc:negctx:max, uenc:negctx)
If cvt:uenc:ratio applies, max number of constants in comparisons
x==const in negative context (equivalently, x!=const in positive
context) to skip UEnc(x). Default 1.
cvt:uenc:ratio (uenc:ratio)
Min ratio (ub-lb)/Nvalues to skip unary encoding for a variable x, where
Nvalues is the number of constants used in conditional comparisons
x==const. Instead, indicator constraints (or big-Ms) are used, if
uenc:negctx also applies. Default 0.
double:allowableGap (allowableGap)
Stop when gap between best possible and best less than this (default 0).
double:artificialCost (artificialCost)
Costs >= this treated as artificials in feasibility pump (default 0).
double:cutoff (cutoff)
Bound on the objective value for all solutions (default 1e+50).
double:dextra3 (dextra3)
Extra double parameter 3 (default 0).
double:dextra4 (dextra4)
Extra double parameter 4 (default 0).
double:dextra5 (dextra5)
Extra double parameter 5 (default 0).
double:dualBound (dualBound)
Initially algorithm acts as if no gap between bounds exceeds this value
(default 1e+10).
double:dualTolerance (dualTolerance)
For an optimal solution no dual infeasibility may exceed this value
(default 1e-07).
double:fixOnDj (fixOnDj)
Try heuristic based on fixing variables with reduced costs greater than
this (default -1).
double:fractionforBAB (fractionforBAB)
Fraction in feasibility pump (default 0.5).
double:increment (increment)
A valid solution must be at least this much better than last integer
solution (default 1e-05).
double:infeasibilityWeight (infeasibilityWeight)
Each integer infeasibility is expected to cost this much (default 0).
double:integerTolerance (integerTolerance)
For a feasible solution no integer variable may be more than this away
from an integer value (default 1e-07).
double:objectiveScale (objectiveScale)
Scale factor to apply to objective (default 1).
double:preTolerance (preTolerance)
Tolerance to use in presolve (default 1e-08).
double:primalTolerance (primalTolerance)
For a feasible solution no primal infeasibility, i.e., constraint
violation, may exceed this value (default 1e-07).
double:primalWeight (primalWeight)
Initially algorithm acts as if it costs this much to be infeasible
(default 1e+10).
double:psi (psi)
Two-dimension pricing factor for Positive Edge criterion (default -0.5).
double:pumpCutoff (pumpCutoff)
Fake cutoff for use in feasibility pump (default 0).
double:pumpIncrement (pumpIncrement)
Fake increment for use in feasibility pump (default 0).
double:ratioGap (ratioGap)
Stop when gap between best possible and best known is less than this
fraction of larger of two (default 0).
double:reallyObjectiveScale (reallyObjectiveScale)
Scale factor to apply to objective in place (default 1).
double:rhsScale (rhsScale)
Scale factor to apply to rhs and bounds (default 1).
double:seconds (seconds)
maximum seconds (default 1e+08).
double:tightenFactor (tightenFactor)
Tighten bounds using this times largest activity at continuous solution
(default -1).
double:zeroTolerance (zeroTolerance)
Kill all coefficients whose absolute value is less than this value
(default 1e-20).
int:cppGenerate (cppGenerate)
Generates C++ code (default -1).
int:cutDepth (cutDepth)
Depth in tree at which to do cuts (default -1).
int:cutLength (cutLength)
Length of a cut (default -1).
int:decompose (decompose)
Whether to try decomposition (default 0).
int:denseThreshold (denseThreshold)
Threshold for using dense factorization (default -1).
int:depthMiniBab (depthMiniBab)
Depth at which to try mini branch-and-bound (default -1).
int:diveOpt (diveOpt)
Diving options (default -1).
int:diveSolves (diveSolves)
Diving solve option (default 100).
int:dualize (dualize)
Solves dual reformulation (default 3).
int:expensiveStrong (expensiveStrong)
Whether to do even more strong branching (default 0).
int:experiment (experiment)
Whether to use testing features (default 0).
int:extra1 (extra1)
Extra integer parameter 1 (default -1).
int:extra2 (extra2)
Extra integer parameter 2 (default -1).
int:extra3 (extra3)
Extra integer parameter 3 (default -1).
int:extra4 (extra4)
Extra integer parameter 4 (default -1).
int:extraVariables (extraVariables)
Allow creation of extra integer variables (default 0).
int:forceSolution (forceSolution)
Whether to use given solution as crash for BAB (default -1).
int:hOptions (hOptions)
Heuristic options (default 0).
int:hotStartMaxIts (hotStartMaxIts)
Maximum iterations on hot start (default 100).
int:idiotCrash (idiotCrash)
Whether to try idiot crash (default -1).
int:logLevel (logLevel)
Level of detail in Coin branch and Cut output (default 1).
int:maxFactor (maxFactor)
Maximum number of iterations between refactorizations (default 200).
int:maxIterations (maxIterations)
Maximum number of iterations before stopping (default 2147483647).
int:maxNodes (maxNodes)
Maximum number of nodes to do (default 2147483647).
int:maxSavedSolutions (maxSavedSolutions)
Maximum number of solutions to save (default -1).
int:maxSolutions (maxSolutions)
Maximum number of feasible solutions to get (default -1).
int:mipOptions (mipOptions)
Dubious options for mip (default 1057).
int:moreMipOptions (moreMipOptions)
More dubious options for mip (default -1).
int:moreSpecialOptions (moreSpecialOptions)
Yet more dubious options for Simplex - see ClpSimplex.hpp (default -1).
int:moreTune (moreTune)
Yet more dubious ideas for feasibility pump (default 0).
int:multipleRootPasses (multipleRootPasses)
Do multiple root passes to collect cuts and solutions (default 0).
int:numberAnalyze (numberAnalyze)
Number of analysis iterations (default -1).
int:outputFormat (outputFormat)
Which output format to use (default 2).
int:passCuts (passCuts)
Number of rounds that cut generators are applied in the root node
(default 20).
int:passFeasibilityPump (passFeasibilityPump)
How many passes to do in the Feasibility Pump heuristic (default 20).
int:passPresolve (passPresolve)
How many passes in presolve (default 5).
int:passTreeCuts (passTreeCuts)
Number of rounds that cut generators are applied in the tree (default
1).
int:pertValue (pertValue)
Method of perturbation (default 50).
int:pOptions (pOptions)
Dubious print options (default 0).
int:preOpt (preOpt)
Presolve options (default -1).
int:pumpTune (pumpTune)
Dubious ideas for feasibility pump (default 1003).
int:randomCbcSeed (randomCbcSeed)
Random seed for Cbc (default -1).
int:randomSeed (randomSeed)
Random seed for Clp (default 1234567).
int:slogLevel (slogLevel)
Level of detail in (LP) Solver output (default 1).
int:slowcutpasses (slowcutpasses)
Maximum number of rounds for slower cut generators (default 10).
int:slpValue (slpValue)
Number of slp passes before primal (default -1).
int:smallFactorization (smallFactorization)
Threshold for using small factorization (default -1).
int:specialOptions (specialOptions)
Dubious options for Simplex - see ClpSimplex.hpp (default -1).
int:sprintCrash (sprintCrash)
Whether to try sprint crash (default -1).
int:strategy (strategy)
Switches on groups of features (default 1).
int:strongBranching (strongBranching)
Number of variables to look at in strong branching (default 5).
int:substitution (substitution)
How long a column to substitute for in presolve (default 3).
int:testOsi (testOsi)
Test OsiObject stuff (default -1).
int:trustPseudoCosts (trustPseudoCosts)
Number of branches before we trust pseudocosts (default 5).
int:tunePreProcess (tunePreProcess)
Dubious tuning parameters for preprocessing (default -1).
int:verbose (verbose)
Switches on longer help on single ? (default 0).
int:vubheuristic (vubheuristic)
Type of VUB heuristic (default -1).
lim:time (timelim, timelimit)
Limit on solve time (in seconds; default: no limit).
lp:dualpivot (dualPivot)
Dual pivot choice algorithm
automatic -
dantzig -
partial -
steepest -
PEsteepest -
PEdantzig -
lp:pfi (PFI)
Whether to use Product Form of Inverse in simplex
off - Turn off
on - Turn on
lp:primalpivot (primalPivot)
Primal pivot choice algorithm
auto!matic -
exact -
dantzig -
partial -
steepest -
change -
sprint -
PEsteepest -
PEdantzig -
mip:combine2Solutions (combine2Solutions)
Whether to use crossover solution heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:combineSolutions (combineSolutions)
Whether to use combine solution heuristic
off -
on -
both -
before -
onquick -
bothquick -
beforequick -
mip:constraintfromCutoff (constraintfromCutoff)
Whether to use cutoff as constraint
off -
on -
variable -
forcevariable -
conflict -
mip:costStrategy (costStrategy)
How to use costs for branching priorities
off -
priorities -
columnOrder -
01first -
01last -
length -
singletons -
nonzero -
generalForce -
mip:dins (Dins)
Whether to try Distance Induced Neighborhood Search
off -
on -
both -
before -
often -
mip:divingcoefficient (DivingCoefficient)
Whether to try Coefficient diving heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:divingfractional (DivingFractional)
Whether to try Fractional diving heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:divingguided (DivingGuided)
Whether to try Guided diving heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:divinglinesearch (DivingLineSearch)
Whether to try Linesearch diving heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:divingpseudocost (DivingPseudoCost)
Whether to try Pseudocost diving heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:divingsome (DivingSome)
Whether to try Diving heuristics
off - disabled
on - use every node in the tree
both -
before -
mip:divingvectorlength (DivingVectorLength)
Whether to try Vectorlength diving heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:dwHeuristic (dwHeuristic)
Whether to try Dantzig Wolfe heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:feasibilitypumpfeasibilityPump
Whether to try the Feasibility Pump heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:greedyheuristic (greedyHeuristic)
Whether to use a greedy heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:heuristics (heuristicsOnOff)
Switches most primal heuristics on or off
off - Turn off
on - Turn on
mip:localtreesearch (localTreeSearch)
Whether to use local tree search when a solution is found
off - Turn off
on - Turn on
mip:naiveheuristics (naiveHeuristics)
Whether to try some stupid heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:nodestrategy (nodeStrategy)
What strategy to use to select the next node from the branch and cut
tree
hybrid -
fewest -
depth -
upfewest -
downfewest -
updepth -
downdepth -
mip:pivotandcomplement (pivotAndComplement)
Whether to try Pivot and Complement heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:pivotandfix (pivotAndFix)
Whether to try Pivot and Fix heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:proximitysearch (proximitySearch)
Whether to do proximity search heuristic
off -
on -
both -
before -
10 -
100 -
300 -
mip:randomizedrounding (randomizedRounding)
Whether to try randomized rounding heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:rens (Rens)
Whether to try Relaxation Enforced Neighborhood Search
off -
on -
both -
before -
200 -
1000 -
10000 -
dj -
djbefore -
usesolution -
mip:rins (Rins)
Whether to try Relaxed Induced Neighborhood Search
off -
on -
both -
before -
often -
mip:round (round)
Whether to round integer variables to integral values before returning
the solution, and whether to report that the solver returned noninteger
values for integer values: sum of
1 ==> Round nonintegral integer variables
2 ==> Modify solve_result
4 ==> Modify solve_message
Default = 0. Modifications that were or would be made are reported in
solve_result and solve_message only if the maximum deviation from
integrality exceeded mip:round_reptol.
mip:round_reptol (round_reptol)
Tolerance for reporting rounding of integer variables to integer values;
see "mip:round". Default = 1e-9.
mip:roundingheuristic (roundingHeuristic)
Whether to use simple (but effective) Rounding heuristic
off - disabled
on - use every node in the tree
both -
before -
mip:vndvariableneighborhoodsearch (VndVariableNeighborhoodSearch)
Whether to try Variable Neighborhood Search
off -
on -
both -
before -
intree -
obj:multi (multiobj)
Whether to use multi-objective optimization:
0 - Single objective, see option obj:no (default)
1 - Multi-objective, solver's native handling if available
2 - Multi-objective, force emulation
When obj:multi>0 and several objectives are present, suffixes
.objpriority, .objweight, .objreltol, and .objabstol on the objectives
are relevant. Objectives with greater .objpriority values (integer
values) have higher priority. Objectives with the same .objpriority are
weighted by .objweight, according to the option obj:multi:weight.
Objectives with positive .objabstol or .objreltol are allowed to be
degraded by lower priority objectives by amounts not exceeding the
.objabstol (absolute) and .objreltol (relative) limits.
Note that with solver's native handling (when obj:multi=1 and
supported), some solvers might have special rules for the tolerances,
especially for LP, and not allow quadratic objectives. See the solver
documentation.
obj:multi:weight (multiobjweight, obj:multi:weights, multiobjweights)
How to interpret each objective's weight sign:
1 - relative to the sense of the 1st objective
2 - relative to its own sense (default)
With the 1st option (legacy behaviour), negative .objweight for
objective i would make objective i's sense the opposite of the model's
1st objective. Otherwise, it would make objective i's sense the opposite
to its sense defined in the model.
obj:no (objno)
Objective to optimize:
0 - None
1 - First (default, if available)
2 - Second (if available), etc.
pre:autoScale
Whether to scale objective, rhs and bounds of problem if they look odd:
off - Turn off
on - Turn on
pre:biasLU
Whether factorization biased towards U:
UU -
UX -
LX -
LL -
pre:factorization (factorization)
Which factorization to use
normal -
dense -
simple -
osl -
pre:preprocess (preprocess)
Whether to use integer preprocessing
off -
on -
save -
equal -
sos -
trysos -
equalall -
strategy -
aggregate -
forcesos -
stopaftersaving -
pre:presolve (presolve)
Whether to presolve problem
on -
off -
more -
file -
pre:scaling (scaling)
Whether to scale problem
off -
equilibrium -
geometric -
automatic -
dynamic -
rowsonly -
pre:sparsefactor (sparseFactor)
Whether factorization treated as sparse
off - Turn off
on - Turn on
sol:chk:fail (chk:fail, checkfail)
Fail on MP solution check violations, with solve result 150.
sol:chk:feastol (sol:chk:eps, chk:eps, chk:feastol)
Absolute tolerance to check objective values, variable and constraint
bounds. Default 1e-6.
sol:chk:feastolrel (sol:chk:epsrel, chk:epsrel, chk:feastolrel)
Relative tolerance to check objective values, variable and constraint
bounds. Default 1e-6.
sol:chk:infeas (chk:infeas, checkinfeas)
Check even infeasible solution condidates, whenever solver reports them.
sol:chk:inttol (sol:chk:inteps, sol:inteps, chk:inttol)
Solution checking tolerance for variables' integrality. Default 1e-5.
sol:chk:mode (solcheck, checkmode, chk:mode)
Solution checking mode. Sum of a subset of the following bits:
1 - Check variable bounds and integrality.
2 - Check original model constraints, as well as any non-linear
expression values reported by the solver.
4 - Check intermediate auxiliary constraints (i.e., those which were
reformulated further).
8 - Check final auxiliary constraints sent to solver.
16 - Check objective values.
32, 64, 128, 256, 512 - similar, but non-linear expressions are
recomputed (vs using their values reported by the solver.)
*Experimental.* This is an idealistic check, because it does not
consider possible tolerances applied by the solver when computing
expression values.
Default: 1+2+512.
sol:chk:prec (chk:prec, chk:precision)
AMPL solution_precision option when checking: number of significant
digits.
sol:chk:round (chk:round, chk:rnd)
AMPL solution_round option when checking: round to this number of
decimals after comma (before comma if negative.)
sol:report_uncertain (report_uncertain_sol)
0/1*: whether to report objective value(s) in solve_message when
solve_result is '?' (unknown).
tech:debug (debug)
0*/1: whether to assist testing & debugging, e.g., by outputting
auxiliary information (mostly via suffixes).
tech:messages (messages)
Controls if Clpnnnn is printed
off - Turn off
on - Turn on
tech:optionfile (optionfile, option:file)
Name of an AMPL solver option file to read (surrounded by 'single' or
"double" quotes if the name contains blanks). Lines that start with #
are ignored. Otherwise, each nonempty line should contain "name=value",
e.g., "lim:iter=500".
tech:outlev (outlev)
0*-4: Whether to write log lines (chatter) to stdout and to file.
tech:outlev_mp (outlev_mp)
0*/1: whether to print MP model information.
tech:timing (timing, tech:report_times, report_times)
0*/1/2: Whether to print and return timings for the run, all times are
wall times. If set to 1, return the solution times in the problem
suffixes 'time_solver', 'time_setup' and 'time', 'time'=
time_solver+time_setup+time_output is a measure of the total time spent
in the solver driver. If set to 2, return more granular times, including
'time_read', 'time_conversion' and 'time_output'.
tech:version (version)
Single-word phrase: report version details before solving the problem.
tech:wantsol (wantsol)
In a stand-alone invocation (no "-AMPL" on the command line), what
solution information to write. Sum of
1 - Write ".sol" file
2 - Primal variables to stdout
4 - Dual variables to stdout
8 - Suppress solution message.
tech:writegraph (cvt:writegraph, writegraph, exportgraph)
File to export conversion graph. Format: JSON Lines.
tech:writemodel (tech:writeprob, writeprob, writemodel, tech:exportfile)
Specifies files where to export the model before solving (repeat the
option for several files.) File name extensions can be ".lp[.7z]",
".mps", etc.
To write a model during iterative solve (e.g., with obj:multi=2), use
tech:writemodel:index.
tech:writemodel:index (tech:writeprob:index, writeprobindex, writemodelindex)
During iterative solve (e.g., with obj:multi=2), the iteration before
which to write solver model. 0 means before iteration is initialized;
positive value - before solving that iteration. Default 0.
tech:writemodelonly (justwriteprob, justwritemodel)
Specifies files where to export the model, no solving (option can be
repeated.) File extensions can be ".dlp", ".mps", etc.