inst/HiGHS/docs/src/options/definitions.md

In Uno: R Interface to the 'Uno' Nonlinear Optimization Solver

List of options

presolve

• Presolve: "off", "choose" or "on"
• Type: string
• Default: "choose"

solver

• LP/QP solver: "choose", "simplex", "ipm", "ipx", "hipo", "pdlp", "qpasm" or "hipdlp",
• Type: string
• Default: "choose"

parallel

• Parallel: "off", "choose" or "on"
• Type: string
• Default: "choose"

run_crossover

• Run IPM crossover: "off", "choose" or "on"
• Type: string
• Default: "on"

time_limit

• Time limit (seconds)
• Type: double
• Range: [0, inf]
• Default: inf

ranging

• Compute cost, bound, RHS and basic solution ranging: "off" or "on"
• Type: string
• Default: "off"

infinite_cost

• Limit on |cost coefficient|: values greater than or equal to this will be treated as infinite
• Type: double
• Range: [1e+15, inf]
• Default: 1e+20

infinite_bound

• Limit on |constraint bound|: values greater than or equal to this will be treated as infinite
• Type: double
• Range: [1e+15, inf]
• Default: 1e+20

small_matrix_value

• Lower limit on |matrix entries|: values less than or equal to this will be treated as zero
• Type: double
• Range: [1e-12, inf]
• Default: 1e-09

large_matrix_value

• Upper limit on |matrix entries|: values greater than or equal to this will be treated as infinite
• Type: double
• Range: [1, inf]
• Default: 1e+15

kkt_tolerance

• If changed from its default value, this tolerance is used for all feasibility and optimality (KKT) measures
• Type: double
• Range: [1e-10, inf]
• Default: 1e-07

primal_feasibility_tolerance

• Primal feasibility tolerance
• Type: double
• Range: [1e-10, inf]
• Default: 1e-07

dual_feasibility_tolerance

• Dual feasibility tolerance
• Type: double
• Range: [1e-10, inf]
• Default: 1e-07

primal_residual_tolerance

• Primal residual tolerance
• Type: double
• Range: [1e-10, inf]
• Default: 1e-07

dual_residual_tolerance

• Dual residual tolerance
• Type: double
• Range: [1e-10, inf]
• Default: 1e-07

optimality_tolerance

• Optimality tolerance
• Type: double
• Range: [1e-10, inf]
• Default: 1e-07

objective_bound

• Objective bound for termination of the dual simplex solver
• Type: double
• Range: [-inf, inf]
• Default: inf

objective_target

• Objective target for termination of the MIP solver
• Type: double
• Range: [-inf, inf]
• Default: -inf

random_seed

• Random seed used in HiGHS
• Type: integer
• Range: {0, 2147483647}
• Default: 0

threads

• Number of threads used by HiGHS (0: automatic)
• Type: integer
• Range: {0, 2147483647}
• Default: 0

user_objective_scale

• Exponent of power-of-two objective scaling for model
• Type: integer
• Range: {-2147483647, 2147483647}
• Default: 0

user_bound_scale

• Exponent of power-of-two bound scaling for model
• Type: integer
• Range: {-2147483647, 2147483647}
• Default: 0

simplex_strategy

• Strategy for simplex solver 0 => Choose; 1 => Dual (serial); 2 => Dual (SIP); 3 => Dual (PAMI); 4 => Primal
• Type: integer
• Range: {0, 4}
• Default: 1

simplex_scale_strategy

• Simplex scaling strategy: off / choose / equilibration (default) / forced equilibration / max value (0/1/2/3/4)
• Type: integer
• Range: {0, 4}
• Default: 2

simplex_dual_edge_weight_strategy

• Strategy for simplex dual edge weights: Choose / Dantzig / Devex / Steepest Edge (-1/0/1/2)
• Type: integer
• Range: {-1, 2}
• Default: -1

simplex_primal_edge_weight_strategy

• Strategy for simplex primal edge weights: Choose / Dantzig / Devex / Steepest Edge (-1/0/1/2)
• Type: integer
• Range: {-1, 2}
• Default: -1

simplex_iteration_limit

• Iteration limit for simplex solver when solving LPs, but not subproblems in the MIP solver
• Type: integer
• Range: {0, 2147483647}
• Default: 2147483647

simplex_update_limit

• Limit on the number of simplex UPDATE operations
• Type: integer
• Range: {0, 2147483647}
• Default: 5000

simplex_max_concurrency

• Maximum level of concurrency in parallel simplex
• Type: integer
• Range: {1, 8}
• Default: 8

output_flag

• Enables or disables solver output
• Type: boolean
• Default: "true"

log_to_console

• Enables or disables console logging
• Type: boolean
• Default: "true"

log_file

• Log file
• Type: string
• Default: ""

write_model_to_file

• Write the model to a file
• Type: boolean
• Default: "false"

write_presolved_model_to_file

• Write the presolved model to a file
• Type: boolean
• Default: "false"

write_solution_to_file

• Write the primal and dual solution to a file
• Type: boolean
• Default: "false"

write_solution_style

• Style of solution file (raw = computer-readable, pretty = human-readable): -1 => HiGHS old raw (deprecated); 0 => HiGHS raw; 1 => HiGHS pretty; 2 => Glpsol raw; 3 => Glpsol pretty; 4 => HiGHS sparse raw
• Type: integer
• Range: {-1, 4}
• Default: 0

glpsol_cost_row_location

• Location of cost row for Glpsol file: -2 => Last; -1 => None; 0 => None if empty, otherwise data file location; 1 <= n <= num_row => Location n; n > num_row => Last
• Type: integer
• Range: {-2, 2147483647}
• Default: 0

read_solution_file

• Read solution file
• Type: string
• Default: ""

read_basis_file

• Read basis file
• Type: string
• Default: ""

write_model_file

• Write model file
• Type: string
• Default: ""

solution_file

• Write solution file
• Type: string
• Default: ""

write_basis_file

• Write basis file
• Type: string
• Default: ""

write_presolved_model_file

• Write presolved model file
• Type: string
• Default: ""

write_iis_model_file

• Write IIS model file
• Type: string
• Default: ""

mip_detect_symmetry

• Whether MIP symmetry should be detected
• Type: boolean
• Default: "true"

mip_allow_restart

• Whether MIP restart is permitted
• Type: boolean
• Default: "true"

mip_max_nodes

• MIP solver max number of nodes
• Type: integer
• Range: {0, 2147483647}
• Default: 2147483647

mip_max_stall_nodes

• MIP solver max number of nodes where estimate is above cutoff bound
• Type: integer
• Range: {0, 2147483647}
• Default: 2147483647

mip_max_start_nodes

• MIP solver max number of nodes when completing a partial MIP start
• Type: integer
• Range: {0, 2147483647}
• Default: 500

mip_improving_solution_save

• Whether improving MIP solutions should be saved
• Type: boolean
• Default: "false"

mip_improving_solution_report_sparse

• Whether improving MIP solutions should be reported in sparse format
• Type: boolean
• Default: "false"

mip_improving_solution_file

• File for reporting improving MIP solutions: not reported for an empty string \"\"
• Type: string
• Default: ""

mip_root_presolve_only

• Whether MIP presolve is only applied at the root node
• Type: boolean
• Default: "false"

mip_lifting_for_probing

• Level of lifting for probing that is used
• Type: integer
• Range: {-1, 2147483647}
• Default: -1

mip_max_leaves

• MIP solver max number of leaf nodes
• Type: integer
• Range: {0, 2147483647}
• Default: 2147483647

mip_max_improving_sols

• Limit on the number of improving solutions found to stop the MIP solver prematurely
• Type: integer
• Range: {1, 2147483647}
• Default: 2147483647

mip_lp_age_limit

• Maximal age of dynamic LP rows before they are removed from the LP relaxation in the MIP solver
• Type: integer
• Range: {0, 32767}
• Default: 10

mip_pool_age_limit

• Maximal age of rows in the MIP solver cutpool before they are deleted
• Type: integer
• Range: {0, 1000}
• Default: 30

mip_pool_soft_limit

• Soft limit on the number of rows in the MIP solver cutpool for dynamic age adjustment
• Type: integer
• Range: {1, 2147483647}
• Default: 10000

mip_pscost_minreliable

• Minimal number of observations before MIP solver pseudo costs are considered reliable
• Type: integer
• Range: {0, 2147483647}
• Default: 8

mip_min_cliquetable_entries_for_parallelism

• Minimal number of entries in the MIP solver cliquetable before neighbourhood queries of the conflict graph use parallel processing
• Type: integer
• Range: {0, 2147483647}
• Default: 100000

mip_feasibility_tolerance

• MIP integrality tolerance
• Type: double
• Range: [1e-10, inf]
• Default: 1e-06

mip_heuristic_effort

• Effort spent for MIP heuristics
• Type: double
• Range: [0, 1]
• Default: 0.05

mip_heuristic_run_feasibility_jump

• Use the feasibility jump heuristic
• Type: boolean
• Default: "true"

mip_heuristic_run_rins

• Use the RINS heuristic
• Type: boolean
• Default: "true"

mip_heuristic_run_rens

• Use the RENS heuristic
• Type: boolean
• Default: "true"

mip_heuristic_run_root_reduced_cost

• Use the rootReducedCost heuristic
• Type: boolean
• Default: "true"

mip_heuristic_run_zi_round

• Use the ZI Round heuristic
• Type: boolean
• Default: "false"

mip_heuristic_run_shifting

• Use the Shifting heuristic
• Type: boolean
• Default: "false"

mip_allow_cut_separation_at_nodes

• Whether cut separation at nodes other than the root node is permitted
• Type: boolean
• Default: "true"

mip_rel_gap

• Tolerance on relative gap, |ub-lb|/|ub|, to determine whether optimality has been reached for a MIP instance
• Type: double
• Range: [0, inf]
• Default: 0.0001

mip_abs_gap

• Tolerance on absolute gap of MIP, |ub-lb|, to determine whether optimality has been reached for a MIP instance
• Type: double
• Range: [0, inf]
• Default: 1e-06

mip_min_logging_interval

• MIP minimum logging interval
• Type: double
• Range: [0, inf]
• Default: 5

mip_lp_solver

• MIP LP solver: "choose", "simplex", "ipm", "ipx" or "hipo"
• Type: string
• Default: "choose"

mip_ipm_solver

• MIP IPM solver: "choose", "ipx" or "hipo"
• Type: string
• Default: "choose"

ipm_optimality_tolerance

• IPM optimality tolerance
• Type: double
• Range: [1e-12, inf]
• Default: 1e-08

ipm_iteration_limit

• Iteration limit for IPM solver
• Type: integer
• Range: {0, 2147483647}
• Default: 2147483647

hipo_system

• HiPO Newton system: "choose", "augmented" or "normaleq"
• Type: string
• Default: "choose"

hipo_parallel_type

• HiPO parallelism: "tree", "node" or "both"
• Type: string
• Default: "both"

hipo_ordering

• HiPO matrix reordering: "choose", "metis", "amd" or "rcm"
• Type: string
• Default: "choose"

hipo_block_size

• Block size for dense linear algebra within HiPO
• Type: integer
• Range: {0, 2147483647}
• Default: 128

pdlp_iteration_limit

• Iteration limit for PDLP solver
• Type: integer
• Range: {0, 2147483647}
• Default: 2147483647

pdlp_scaling_mode

• Scaling mode for PDLP solver (default = 5): 1 => Ruiz; 2 => L2; 4 => PC
• Type: integer
• Range: {0, 7}
• Default: 5

pdlp_ruiz_iterations

• Number of Ruiz scaling iteraitons for PDLP solver
• Type: integer
• Range: {0, 2147483647}
• Default: 10

pdlp_restart_strategy

• Restart strategy for PDLP solver: 0 => off; 1 => fixed; 2 => adaptive; 3 => Halpern
• Type: integer
• Range: {0, 3}
• Default: 2

pdlp_cupdlpc_restart_method

• Restart mode for cuPDLP-C solver: 0 => none; 1 => GPU (default); 2 => CPU
• Type: integer
• Range: {0, 2}
• Default: 1

pdlp_step_size_strategy

• Step size strategy for PDLP solver: 0 => fixed; 1 => adaptive; 2 => Malitsky-Pock; 3 => PID
• Type: integer
• Range: {0, 3}
• Default: 1

pdlp_optimality_tolerance

• PDLP optimality tolerance
• Type: double
• Range: [1e-10, inf]
• Default: 1e-07

qp_iteration_limit

• Iteration limit for the active set QP solver
• Type: integer
• Range: {0, 2147483647}
• Default: 2147483647

qp_nullspace_limit

• Nullspace limit for the active set QP solver
• Type: integer
• Range: {0, 2147483647}
• Default: 4000

qp_regularization_value

• Regularization value added to the Hessian in the active set QP solver
• Type: double
• Range: [0, inf]
• Default: 1e-07

iis_strategy

• Strategy for IIS calculation: 0 => Light test; 1 => Try dual ray; 2 => Try elastic LP; 4 => Prioritise columns; 8 => Find true IIS; 16 => Find relaxation IIS for MIP
• Type: integer
• Range: {0, 31}
• Default: 0

iis_time_limit

• Time limit for computing IIS (seconds)
• Type: double
• Range: [0, inf]
• Default: inf

blend_multi_objectives

• Blend multiple objectives or apply lexicographically
• Type: boolean
• Default: "true"

Uno documentation built on Aug. 30, 2026, 5:07 p.m.