Struct RecombinationHistory

pub struct RecombinationHistory { /* private fields */ }

Precomputed recombination history for fast X_e(z) lookups.

Integrates the Peebles ODE once on construction and stores a table of (z, X_e) pairs. Subsequent lookups use binary search + linear interpolation, making each call O(log N) instead of O(N_ode).

For z above the Peebles regime (z > z_switch ~ 1575), the cheap Saha formula is used directly (no table needed).

Implementations

impl RecombinationHistory

pub fn new(cosmo: &Cosmology) -> Self

Build the recombination history table for a given cosmology.

Integrates the Peebles ODE from z_switch down to z=1 with dz=0.5, storing total X_e (H + He) at each step.

pub fn x_e(&self, z: f64) -> f64

Look up X_e(z) using the cached table.

• z > 8000: fully ionized (Saha for He)
• z_switch < z ≤ 8000: Saha for H + He (cheap, no table)
• z ≤ z_switch: interpolate from precomputed table