scip (version 1.10.0-2)

scip_control: SCIP solver control parameters

Description

Create a list of control parameters for the SCIP solver. Parameters are organized into logical groups: output, limits, tolerances, presolving, LP, branching, and heuristics. Any SCIP parameter can also be set directly using its native path via ....

Usage

scip_control(
  verbose = TRUE,
  verbosity_level = 3L,
  display_freq = 100L,
  time_limit = Inf,
  node_limit = -1L,
  stall_node_limit = -1L,
  sol_limit = -1L,
  best_sol_limit = -1L,
  mem_limit = Inf,
  restart_limit = -1L,
  gap_limit = 0,
  abs_gap_limit = 0,
  feastol = 1e-06,
  dualfeastol = 1e-07,
  epsilon = 1e-09,
  presolving = TRUE,
  presolve_rounds = -1L,
  lp_threads = 1L,
  lp_iteration_limit = -1L,
  lp_scaling = TRUE,
  branching_score = "p",
  heuristics_emphasis = "default",
  threads = 1L,
  ...
)

Value

A named list of class "scip_control" with components:

verbose

Logical; verbosity flag.

scip_params

Named list; all parameters as SCIP native paths.

Arguments

verbose

Logical; print solver output. Default TRUE.

verbosity_level

Integer 0--5; verbosity detail. Default 3.

display_freq

Integer; node display frequency. Default 100.

time_limit

Numeric; time limit in seconds. Default Inf.

node_limit

Integer; max nodes. Default -1L.

stall_node_limit

Integer; stall nodes. Default -1L.

sol_limit

Integer; solution limit. Default -1L.

best_sol_limit

Integer; improving solution limit. Default -1L.

mem_limit

Numeric; memory limit in MB. Default Inf.

restart_limit

Integer; restart limit. Default -1L.

gap_limit

Numeric; relative MIP gap. Default 0.

abs_gap_limit

Numeric; absolute gap. Default 0.

feastol

Numeric; feasibility tolerance. Default 1e-6.

dualfeastol

Numeric; dual feasibility tolerance. Default 1e-7.

epsilon

Numeric; zero tolerance. Default 1e-9.

presolving

Logical; enable presolving. Default TRUE.

presolve_rounds

Integer; presolve rounds. Default -1L.

lp_threads

Integer; LP solver threads. Default 1L.

lp_iteration_limit

Integer; LP iteration limit. Default -1L.

lp_scaling

Logical; LP scaling. Default TRUE.

branching_score

Character; score function. Default "p".

heuristics_emphasis

Character; heuristic emphasis. Default "default".

threads

Integer; parallel solving threads. Default 1L. See Parallel section for caveats.

...

Additional SCIP parameters as name-value pairs, using SCIP's native hierarchical parameter paths (e.g., "lp/fastmip" = 1, "conflict/enable" = FALSE). See the SCIP parameter documentation for the full list.

Output

verbose

Logical; print solver output. Default TRUE.

verbosity_level

Integer 0--5; verbosity detail (0 = none, 3 = normal, 5 = full). Default 3. Ignored if verbose = FALSE.

display_freq

Integer; display a status line every this many nodes (-1 = never). Default 100.

Termination Limits

time_limit

Numeric; maximum solving time in seconds. Default Inf (no limit).

node_limit

Integer; maximum number of branch-and-bound nodes. Default -1L (no limit).

stall_node_limit

Integer; nodes without improvement before stopping. Default -1L (no limit).

sol_limit

Integer; stop after finding this many feasible solutions. Default -1L (no limit).

best_sol_limit

Integer; stop after this many improving solutions. Default -1L (no limit).

mem_limit

Numeric; memory limit in MB. Default Inf (no limit).

restart_limit

Integer; maximum restarts. Default -1L (no limit).

Tolerances

gap_limit

Numeric; relative MIP gap tolerance; solver stops when the gap falls below this value. Default 0 (prove optimality).

abs_gap_limit

Numeric; absolute gap between primal and dual bound. Default 0.

feastol

Numeric; feasibility tolerance for LP constraints. Default 1e-6.

dualfeastol

Numeric; dual feasibility tolerance. Default 1e-7.

epsilon

Numeric; absolute values below this are treated as zero. Default 1e-9.

Presolving

presolving

Logical; enable presolving. Default TRUE.

presolve_rounds

Integer; maximum presolving rounds (-1 = unlimited). Default -1L.

LP

lp_threads

Integer; number of threads for LP solver. Default 1L.

lp_iteration_limit

Integer; LP iteration limit per solve (-1 = no limit). Default -1L.

lp_scaling

Logical; enable LP scaling. Default TRUE.

Branching

branching_score

Character; branching score function: "s" (sum), "p" (product), "q" (quotient). Default "p".

Heuristics

heuristics_emphasis

Character; heuristic emphasis setting: "default", "aggressive", "fast", or "off". Default "default".

Parallel

threads

Integer; number of threads for concurrent solving. Default 1L. Note: concurrent solving may require a SCIP build compiled with parallel support (e.g., PARASCIP=true); not all installations provide this.

See Also

scip_solve, scip_set_param

Examples

## Quick solve with 60-second time limit
ctrl <- scip_control(time_limit = 60)

## Quiet solve with 1% gap tolerance
ctrl <- scip_control(verbose = FALSE, gap_limit = 0.01)

## Aggressive heuristics, no presolving
ctrl <- scip_control(heuristics_emphasis = "aggressive", presolving = FALSE)

## Pass a native SCIP parameter directly
ctrl <- scip_control("conflict/enable" = FALSE, "separating/maxrounds" = 5L)