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newton_raphson_solve

pedalkernel::elements::nonlinear::solver

Function newton_raphson_solve 

pub fn newton_raphson_solve<F>(
    a: f64,
    rp: f64,
    v: f64,
    max_iter: usize,
    tolerance: f64,
    v_clamp: Option<(f64, f64)>,
    step_limit: Option<f64>,
    device_iv: F,
) -> f64
where
    F: FnMut(f64) -> (f64, f64),
Expand description

Unified Newton-Raphson solver for all WDF nonlinear root elements.

Every nonlinear element in the WDF tree solves the same constraint equation:

f(v) = a - 2v - 2·Rp·i(v) = 0

where a is the incident wave, Rp is the port resistance, v is the voltage across the element, and i(v) is the device-specific current.

The device I-V characteristic is provided as a closure returning (current, d_current/d_voltage) at a given voltage.

Returns the reflected wave b = 2v - a.

§Parameters

  • a: Incident wave from the WDF tree
  • rp: Port resistance (Ω)
  • v: Initial guess for the voltage (mutable, used as starting point)
  • max_iter: Maximum iterations (bounded for real-time safety)
  • tolerance: Convergence threshold for |dv|
  • v_clamp: Optional (min, max) voltage clamping bounds
  • step_limit: If the raw Newton step exceeds this, the step is halved to prevent overshoot. Pass None for standard (undamped) Newton.
  • device_iv: Closure returning (i, di_dv) for a given voltage