oximo-highs

HiGHS LP/MILP backend for oximo.

Wraps the highs crate (HiGHS bundled, no separate install required). Supports LP and MILP model kinds.

Usage

Most users should depend on the umbrella oximo crate with the highs feature (enabled by default):

[dependencies]
oximo = "0.1"

To use this crate directly:

[dependencies]
oximo-highs = "0.1"
oximo-core   = "0.1"
oximo-solver = "0.1"

Quick example

use oximo_core::prelude::*;
use oximo_highs::{Highs, HighsOptions};
use oximo_solver::{Solver, SolverStatus};

let m = Model::new("toy");
let x = m.var("x").lb(0.0).build();
let y = m.var("y").lb(0.0).ub(4.0).build();
m.constraint("c1", (x + 2.0 * y).le(14.0));
m.constraint("c2", (3.0 * x - y).ge(0.0));
m.maximize(3.0 * x + 4.0 * y);

let result = Highs.solve(&m, &HighsOptions::default()).unwrap();
assert_eq!(result.status, SolverStatus::Optimal);
println!("obj = {}", result.objective.unwrap()); // 34.0
println!("x   = {}", result.value_of(x).unwrap()); // 6.0
println!("y   = {}", result.value_of(y).unwrap()); // 4.0

Options

HighsOptions is a typed builder. All methods return Self for chaining.

Method	Type	HiGHS option	Default
`.time_limit(Duration)`	universal	`time_limit`	none
`.threads(usize)`	universal	`threads`	none
`.verbose(bool)`	universal	`output_flag`, `log_to_console`	none
`.mip_gap(f64)`	HiGHS-only	`mip_rel_gap`	none
`.presolve(HighsPresolve)`	HiGHS-only	`presolve`	none
`.method(HighsMethod)`	HiGHS-only	`solver`	none
`.parallel(bool)`	HiGHS-only	`parallel`	none

HighsMethod variants: Choose (let HiGHS decide), Simplex, Ipm (interior-point), PdLp (first-order).

HighsPresolve variants: Off, On, Auto ("choose").

use std::time::Duration;
use oximo_highs::{HighsOptions, HighsMethod, HighsPresolve};
use oximo_solver::UniversalOptionsExt;

let opts = HighsOptions::default()
    .time_limit(Duration::from_secs(60))
    .threads(4)
    .mip_gap(0.01)
    .presolve(HighsPresolve::On)
    .method(HighsMethod::Ipm)
    .parallel(true);

Result

SolverResult fields populated on Optimal or Feasible:

objective - objective value (adjusted for any constant term)
primal - variable values, keyed by VarId; access via result.value_of(var)
dual - constraint duals, keyed by ConstraintId
reduced_costs - variable reduced costs, keyed by VarId
solve_time - wall time measured around the HiGHS solve call

License