Struct Lfd 

pub struct Lfd {
    pub coefs: Vec<Vec<f64>>,
}

A linear differential operator of the form Lx(t) = D^m x(t) + β_{m-1}(t)·D^{m-1}x(t) + … + β₀(t)·x(t).

The operator holds m weight functions β₀, …, β_{m-1} (where m is the order of L). Each weight function is sampled on the same evaluation grid that is later supplied to Lfd::apply.

Constant-coefficient operators

A length-1 inner Vec<f64> in coefs is treated as a constant and broadcast to all grid points. For example, coefs = vec![vec![-9.87]] represents the operator Lx = Dx - 9.87·x (order 1, constant negative spring constant).

Fields

coefs: Vec<Vec<f64>>

Weight functions β₀(t), …, β_{m-1}(t), each sampled on the evaluation grid.

coefs.len() equals the operator order m. coefs[k] must have length either 1 (constant, broadcast) or n_pts (grid-sampled), where n_pts = argvals.len() when apply is called.

Implementations

impl Lfd

pub fn apply( &self, data: &FdMatrix, argvals: &[f64], ) -> Result<FdMatrix, FdarError>

Apply the operator to each curve in data.

For a curve xᵢ, computes the scalar sequence Lxᵢ(t_j) = D^m xᵢ(t_j) + Σ_{k=0}^{m-1} βₖ(t_j) · D^k xᵢ(t_j).

Derivatives are estimated via the iterated finite-difference scheme in crate::helpers::gradient (5-point stencil on uniform grids, 3-point Lagrange on non-uniform grids).

Arguments

• data — Functional data matrix (n × n_pts); each row is one curve.
• argvals — Evaluation points (length n_pts, must be sorted ascending).

Errors

• FdarError::InvalidParameter if coefs is empty (m = 0); use coefs = vec![vec![0.0]] for a pure first-derivative operator.
• FdarError::InvalidDimension if n_pts < 2 (single-point grid cannot produce derivatives).
• FdarError::InvalidDimension if argvals.len() != data.ncols().
• FdarError::InvalidDimension if any coefs[k] has a length other than 1 or n_pts.

Returns

An FdMatrix of the same shape as data, containing the operator output.

Trait Implementations

impl Clone for Lfd

fn clone(&self) -> Lfd

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Lfd

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

Formats the value using the given formatter.

impl PartialEq for Lfd

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Lfd