simplex_trace/
error.rs

1use std::fmt;
2
3/// Errors returned by [`solve`](crate::solve).
4///
5/// Infeasible and unbounded problems are *not* errors: they are reported
6/// through [`Status`](crate::Status).
7#[derive(Clone, Debug, PartialEq, Eq)]
8#[non_exhaustive]
9pub enum Error {
10    /// The problem is malformed (e.g. a constraint with the wrong number of coefficients).
11    InvalidProblem(String),
12    /// [`Method::Simplex`](crate::Method::Simplex) was requested but the problem has `>=` or `=`
13    /// constraints, which need artificial variables. Use `BigM` or `TwoPhase`.
14    ArtificialVariablesRequired,
15    /// The iteration limit in [`Options`](crate::Options) was reached (possible cycling).
16    IterationLimit(usize),
17}
18
19impl fmt::Display for Error {
20    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
21        match self {
22            Error::InvalidProblem(msg) => write!(f, "invalid problem: {msg}"),
23            Error::ArtificialVariablesRequired => write!(
24                f,
25                "this problem needs artificial variables; use Method::BigM or Method::TwoPhase"
26            ),
27            Error::IterationLimit(n) => write!(f, "iteration limit of {n} reached"),
28        }
29    }
30}
31
32impl std::error::Error for Error {}
simplex_trace/error.rs

simplex_trace/
error.rs
