Enum ImplicitError 

#[non_exhaustive]
pub enum ImplicitError {
    Singular,
    DimensionMismatch {
        field: &'static str,
        expected: usize,
        actual: usize,
    },
}

Reason a dense implicit-differentiation call failed.

Marked #[non_exhaustive] so future variants can be added without breaking exhaustive matches.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Singular

F_z could not be used for a reliable solve. Fires in three situations, currently collapsed under one name because the dense LU does not expose which branch tripped:

1. Structural singularity — linalg::lu_factor encountered an exactly-zero pivot (e.g. a rank-deficient F_z).
2. Numeric singularity — a pivot below ε·n·‖F_z‖∞ (the relative threshold anchored on the matrix infinity norm).
3. Non-finite input or intermediate — a NaN or ±Inf reached the LU pivot (rejected up-front by lu_factor to prevent silent NaN-tainted factors), or, for implicit_hvp / implicit_hessian, the nested-dual forward pass produced non-finite higher-order coefficients that would poison the back-solve output.

#[non_exhaustive] leaves room to split these cases (or to align with a future unified naming axis across dense and sparse implicit modules) without a breaking change.

DimensionMismatch

A runtime-supplied vector argument to a public implicit_* fn had an unexpected length. field names the argument (e.g. "x_dot", "z_bar", "v", "w"), expected is the length the API requires (typically num_states or x.len()), actual is the length the caller supplied.

Tape-shape contract mismatches (checked in validate_inputs) continue to panic — those are programmer-contract violations, not recoverable runtime failures.

Fields

field: &'static str

expected: usize

actual: usize

Trait Implementations

impl Clone for ImplicitError

fn clone(&self) -> ImplicitError

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ImplicitError

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

Formats the value using the given formatter.

impl Display for ImplicitError

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

Formats the value using the given formatter.

impl Error for ImplicitError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.