Function beta_decomposition 

pub fn beta_decomposition(
    fit: &FregreLmResult,
) -> Result<BetaDecomposition, FdarError>

Decompose beta(t) = sum_k coef_k * phi_k(t) for a linear functional regression.

Errors

Returns FdarError::InvalidParameter if fit.ncomp is zero. Returns FdarError::InvalidDimension if fit.fpca.mean has zero length.