Function fpc_shap_values 

pub fn fpc_shap_values(
    fit: &FregreLmResult,
    data: &FdMatrix,
    scalar_covariates: Option<&FdMatrix>,
) -> Result<FpcShapValues, FdarError>

Exact SHAP values for a linear functional regression model.

For linear models, SHAP values are exact: values[(i,k)] = coef[1+k] * (score_i_k - mean_k). The efficiency property holds: base_value + sum_k values[(i,k)] ~ fitted_values[i] (with scalar covariate effects absorbed into the base value).

Errors

Returns FdarError::InvalidDimension if data has zero rows or its column count does not match fit.fpca.mean. Returns FdarError::InvalidParameter if fit.ncomp is zero.