Enum MaternIdentifiability 

pub enum MaternIdentifiability {
    None,
    CenterSumToZero,
    CenterLinearOrthogonal,
    FrozenTransform {
        transform: Array2<f64>,
        nullspace_shrinkage_survived: Option<bool>,
    },
}

Per-smooth identifiability policy for Matérn kernel coefficients.

These constraints are geometric (center-based), so they are stable across train/predict and do not depend on response weights.

Variants

None

Keep the unconstrained kernel coefficient space.

CenterSumToZero

Enforce 1^T alpha = 0 at center locations (removes constant drift).

CenterLinearOrthogonal

Enforce orthogonality to [1, c_1, ..., c_d] at centers. Use this when explicit linear terms should own global trends.

FrozenTransform

Freeze a fit-time transform Z so prediction cannot drift.

nullspace_shrinkage_survived freezes the double-penalty nullspace-shrinkage decision alongside the transform (gam#787/#860). The matern double-penalty path emits a DoublePenaltyNullspace candidate iff build_nullspace_shrinkage_penalty(&projected_kernel) finds a near-zero eigenvalue — but that spectral test is κ-DEPENDENT (its tolerance scales with λ_max), so a near-zero eigenvalue can cross the threshold as the κ-optimizer rebuilds the design at each trial length-scale. That flips the learned-penalty count 6↔7 across the rebuild and the rebuilt design’s ρ dimension then disagrees with the frozen joint setup (“joint hyper rho dimension mismatch” → every κ seed fails startup validation). Freezing the bootstrap-κ decision here (Some(true) = always emit the shrinkage candidate, Some(false) = never) keeps the penalty count INVARIANT across the κ rebuild so κ actually optimizes. None = decide via the spectral test (the non-frozen / cold-build behavior; also the serde back-compat default for transforms frozen before this field existed).

Fields

transform: Array2<f64>

nullspace_shrinkage_survived: Option<bool>

Trait Implementations

impl Clone for MaternIdentifiability

fn clone(&self) -> MaternIdentifiability

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MaternIdentifiability

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

Formats the value using the given formatter.

impl Default for MaternIdentifiability

fn default() -> MaternIdentifiability

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for MaternIdentifiability

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for MaternIdentifiability

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

where __S: Serializer,

Serialize this value into the given Serde serializer.