Struct ErfcStep 

pub struct ErfcStep;

Erfc step: (A / 2) · erfc((x − x₀) / (σ · √2))

Parameters (in order): [amplitude, center, sigma]

Uses libm::erfc. Commonly used for XANES / XPS pre-edge backgrounds.

∂/∂amplitude = ½ · erfc(u) ∂/∂center = A / (σ · √(2π)) · exp(−u²) [u = (x−x₀)/(σ√2)] ∂/∂sigma = A · u / (σ · √(2π)) · exp(−u²)

Trait Implementations

impl Model for ErfcStep

fn eval(&self, x: &[f64], params: &[f64]) -> f64

Evaluate the model at coordinate x with the given params.

fn jacobian(&self, x: &[f64], params: &[f64]) -> Vec<f64>

Jacobian — one derivative per parameter, in the same order as param_names().

fn jacobian_into(&self, x: &[f64], params: &[f64], out: &mut [f64])

Fill a pre-allocated slice with Jacobian values (one entry per parameter).

fn param_names(&self) -> Vec<Cow<'static, str>>

Ordered parameter names, matching the layout expected by eval and jacobian.

fn eval_slice_into(&self, xs: &[f64], params: &[f64], out: &mut [f64])

Batch evaluation of a 1-D model: fill out[i] = eval([xs[i]], params).

fn jac_slice_into(&self, xs: &[f64], params: &[f64], out: &mut [f64])

Batch Jacobian for a 1-D model: fill out in row-major layout [i * params.len() + j] = d(model)/d(params[j]) at xs[i].

fn n_dims(&self) -> usize

Number of coordinate dimensions consumed from x. Defaults to 1.