Struct LinearExpr 

pub struct LinearExpr {
    pub constant: Rational,
    pub coefficients: BTreeMap<i64, Rational>,
}

A linear expression of the form c₀ + c₁x₁ + c₂x₂ + … + cₙxₙ.

Stored as a constant term plus a sparse map of variable coefficients. Variables with coefficient 0 are automatically removed.

Representation

The expression 3 + 2x - y is stored as:

• constant = 3
• coefficients = {0: 2, 1: -1} (assuming x is var 0, y is var 1)

Fields

constant: Rational

The constant term c₀.

coefficients: BTreeMap<i64, Rational>

Maps variable index to its coefficient (sparse representation).

Implementations

impl LinearExpr

pub fn constant(c: Rational) -> Self

Create a constant expression

pub fn var(idx: i64) -> Self

Create a single variable expression: 1*x_idx + 0

pub fn add(&self, other: &LinearExpr) -> LinearExpr

Add two linear expressions

pub fn neg(&self) -> LinearExpr

Negate a linear expression

pub fn sub(&self, other: &LinearExpr) -> LinearExpr

Subtract two linear expressions

pub fn scale(&self, c: &Rational) -> LinearExpr

Scale a linear expression by a rational constant

pub fn is_constant(&self) -> bool

Check if this is a constant expression (no variables)

pub fn get_coeff(&self, var: i64) -> Rational

Get coefficient of a variable (0 if not present)

Trait Implementations

impl Clone for LinearExpr

fn clone(&self) -> LinearExpr

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for LinearExpr

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

Formats the value using the given formatter.

impl PartialEq for LinearExpr

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for LinearExpr

impl StructuralPartialEq for LinearExpr