Function fermionic_single_pole 

pub fn fermionic_single_pole(tau: f64, omega: f64, beta: f64) -> f64

Compute fermionic single-pole Green’s function at imaginary time τ

Evaluates G(τ) = -exp(-ω×τ) / (1 + exp(-β×ω)) for a single pole at frequency ω.

Supports extended τ ranges with anti-periodic boundary conditions:

• G(τ + β) = -G(τ) (fermionic anti-periodicity)
• Valid for τ ∈ (-β, 2β)

Arguments

• tau - Imaginary time (can be outside [0, β))
• omega - Pole position (real frequency)
• beta - Inverse temperature

Returns

Real-valued Green’s function G(τ)

Example

let beta = 1.0;
let omega = 5.0;
let tau = 0.5 * beta;
let g = fermionic_single_pole(tau, omega, beta);