Struct EnergyScaleTransmissionModel 

pub struct EnergyScaleTransmissionModel { /* private fields */ }

Transmission model with energy-scale calibration parameters (t₀, L_scale).

Wraps precomputed cross-sections and re-maps the energy grid at each evaluation:

1. Convert nominal energy → TOF: t = TOF_FACTOR * L / √E_nom
2. Apply calibration: t_corr = t - t₀, E_corr = (TOF_FACTOR * L * L_scale / t_corr)²
3. Interpolate cross-sections σ(E_nom) → σ(E_corr)
4. Beer-Lambert + resolution on the corrected grid

This is equivalent to SAMMY’s TZERO parameters.

The Jacobian for t₀ and L_scale is computed via finite differences (the energy-grid remapping is nonlinear and not easily differentiable analytically through the interpolation + resolution pipeline).

Implementations

impl EnergyScaleTransmissionModel

pub fn new( cross_sections: Arc<Vec<Vec<f64>>>, density_indices: Arc<Vec<usize>>, nominal_energies: Vec<f64>, flight_path_m: f64, t0_index: usize, l_scale_index: usize, instrument: Option<Arc<InstrumentParams>>, ) -> Self

Create a new energy-scale transmission model.

Arguments

• cross_sections — Precomputed σ(E) on the nominal grid.
• density_indices — Maps isotope index → parameter index.
• nominal_energies — Energy grid in eV (ascending).
• flight_path_m — Nominal flight path in meters.
• t0_index — Index of t₀ parameter.
• l_scale_index — Index of L_scale parameter.
• instrument — Optional resolution function.

Trait Implementations

impl FitModel for EnergyScaleTransmissionModel

fn analytical_jacobian( &self, params: &[f64], free_param_indices: &[usize], _y_current: &[f64], ) -> Option<FlatMatrix>

Jacobian: analytical for density parameters, finite-difference for t₀ and L_scale.

fn evaluate(&self, params: &[f64]) -> Result<Vec<f64>, FittingError>

Evaluate the model for the given parameters.

impl ForwardModel for EnergyScaleTransmissionModel

fn predict(&self, params: &[f64]) -> Result<Vec<f64>, FittingError>

Predict model output for the given parameter vector.

fn jacobian( &self, params: &[f64], free_param_indices: &[usize], y_current: &[f64], ) -> Option<Vec<Vec<f64>>>

Analytical Jacobian (column-major layout).

fn n_data(&self) -> usize

Number of data points in the model output.

fn n_params(&self) -> usize

Number of parameters (total, including fixed).