Struct NlCounts 

pub struct NlCounts {
    pub nl_cons: usize,
    pub nl_objs: usize,
    pub nl_vars_cons: usize,
    pub nl_vars_objs: usize,
    pub nl_vars_both: usize,
}

The .nl header’s nonlinearity census — lines 3 and 5 of Gay’s header table (Hooking Your Solver to AMPL, §D and Table 1).

AMPL has already done this analysis when it writes the file, so these are facts about the model that cost nothing to keep and would otherwise have to be recovered by walking every expression tree in it.

 55 1        # nonlinear constraints, objectives          -> nl_cons, nl_objs
 100 110 100 # nonlinear vars in constraints, objectives, both

Two properties of the format make these usable rather than merely informative, and both are asserted against the fixture corpus in crates/pounce-cli/tests/nl_header_counts.rs:

1. Nonlinear rows come first. Constraints 0..nl_cons are the ones with a nonlinear body; objectives 0..nl_objs likewise.
2. Nonlinear variables come first. The .nl variable order is “nonlinear in both, then constraints-only, then objectives-only, then everything linear”, so the variables that appear nonlinearly occupy a prefix of length NlCounts::nonlinear_vars.

The counts are what the writer asserted, which is not always what the parsed trees say: parse_nl_text folds a variable-free C body into the row bounds (gh #492), so a row counted in nl_cons can arrive here with a nonlinear part of Const(0.0). The discrepancy is one-directional — the header only ever over-states nonlinearity relative to the trees — and every consumer below is written to be sound under exactly that direction.

Fields

nl_cons: usize

nlc: constraints with a nonlinear body.

nl_objs: usize

nlo: objectives with a nonlinear body.

nl_vars_cons: usize

nlvc: variables appearing nonlinearly in constraints. Includes the Self::nl_vars_both variables that are also nonlinear in an objective.

nl_vars_objs: usize

nlvo: variables appearing nonlinearly in objectives. Also includes Self::nl_vars_both.

nl_vars_both: usize

nlvb: variables appearing nonlinearly in both a constraint and an objective. Counted a second and third time in the two fields above, which is why the total is an inclusion–exclusion and not a sum.

Implementations

impl NlCounts

pub fn nonlinear_vars(&self) -> usize

Number of distinct variables that appear nonlinearly anywhere: nlvc + nlvo − nlvb, because nlvb is double-counted by the other two. Saturating, so a malformed header cannot underflow.

This is not max(nlvc, nlvo): for min x₀² s.t. x₁² ≤ 1 the counts are nlvc = nlvo = 1, nlvb = 0 and there are two nonlinear variables, not one.

Trait Implementations

impl Clone for NlCounts

fn clone(&self) -> NlCounts

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for NlCounts

impl Debug for NlCounts

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

Formats the value using the given formatter.

impl Eq for NlCounts

impl PartialEq for NlCounts

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for NlCounts