Struct ArctanStep 

pub struct ArctanStep;

Arctan step: A · (½ + (1/π) · arctan((x − x₀) / σ))

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

∂/∂amplitude = (½ + (1/π)·arctan(ε)) ∂/∂center = −A / (π · σ · (1 + ε²)) [ε = (x−x₀)/σ] ∂/∂sigma = −A · ε / (π · σ · (1 + ε²))

Trait Implementations

impl Model for ArctanStep

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.