Struct Snapshot 

#[non_exhaustive]
pub struct Snapshot {
    pub sense: Sense,
    pub objective_label: String,
    pub columns: Vec<String>,
    pub basis: Vec<usize>,
    pub rows: Vec<Vec<Rational>>,
    pub rhs: Vec<Rational>,
    pub z: Vec<Coef>,
    pub z_rhs: Coef,
}

A full copy of the tableau at one point in time.

The tableau is always expressed in the sense of the objective being optimized, as in Taha’s textbook: the objective row holds z_j - c_j with the real costs c_j, and z_rhs is the real objective value. A maximization tableau is optimal when every z_j - c_j >= 0; a minimization tableau when every z_j - c_j <= 0 (see Snapshot::is_optimal).

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

sense: Sense

Sense of the objective in this tableau. Phase 1 of the two-phase method is always Sense::Minimize (it minimizes r, the sum of the artificial variables).

objective_label: String

Name of the objective row: "z", or "r" in phase 1 of the two-phase method.

columns: Vec<String>

Column names (original variables, then slack/surplus, then artificial).

basis: Vec<usize>

For each constraint row, the index of its basic column.

rows: Vec<Vec<Rational>>

Constraint rows, without the right-hand side.

rhs: Vec<Rational>

Right-hand side of each constraint row.

z: Vec<Coef>

Objective row, z_j - c_j per column (may contain the symbolic M).

z_rhs: Coef

Current value of the objective (may contain the symbolic M in Big-M).

Implementations

impl Snapshot

pub fn is_optimal(&self) -> bool

true when no column can improve the objective: all z_j - c_j >= 0 when maximizing, all <= 0 when minimizing.

pub fn is_feasible(&self) -> bool

true when every right-hand side is >= 0. Primal methods keep this at every iteration; the dual simplex works towards it, so its intermediate tableaus are optimal but not feasible.

Trait Implementations

impl Clone for Snapshot

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Snapshot

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Snapshot

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for Snapshot

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Snapshot

impl PartialEq for Snapshot

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for Snapshot

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Snapshot