Function sim_kl 

pub fn sim_kl(
    n: usize,
    phi: &FdMatrix,
    big_m: usize,
    lambda: &[f64],
    seed: Option<u64>,
) -> FdMatrix

Simulate functional data via Karhunen-Loève expansion.

Generates n curves using the truncated KL representation: f_i(t) = Σ_{k=1}^{M} ξ_{ik} φ_k(t) where ξ_{ik} ~ N(0, λ_k)

Arguments

• n - Number of curves to generate
• phi - Eigenfunctions matrix (m × big_m) as FdMatrix
• big_m - Number of eigenfunctions
• lambda - Eigenvalues (length big_m)
• seed - Optional random seed for reproducibility

Returns

Data FdMatrix of size n × m