Function gtau_single_pole 

pub fn gtau_single_pole<S: StatisticsType>(
    tau: f64,
    omega: f64,
    beta: f64,
) -> Result<f64, Error>

Generic single-pole Green’s function at imaginary time τ

Computes G(τ) for either fermionic or bosonic statistics based on the type parameter S. Both use G(τ) = -exp(-ω×τ) / (1 ± exp(-β×ω)) (+ for fermions, - for bosons), the imaginary-time counterpart of giwn_single_pole’s G(iν) = 1/(iν - ω).

Type Parameters

• S - Statistics type (Fermionic or Bosonic)

Arguments

• tau - Imaginary time τ ∈ [-β, β]; τ < 0 is mapped to [0, β] by (anti-)periodicity (see fermionic_single_pole and bosonic_single_pole)
• omega - Pole position (real frequency)
• beta - Inverse temperature

Returns

Real-valued Green’s function G(τ)

Errors

• Error::InvalidParameter if beta is not positive and finite, or omega is not finite
• Error::OutOfDomain if tau is outside [-β, β] or NaN

Example

use sparse_ir::traits::{Bosonic, Fermionic};
use sparse_ir::{bosonic_single_pole, fermionic_single_pole, gtau_single_pole};

let g_f = gtau_single_pole::<Fermionic>(0.5, 5.0, 1.0).unwrap();
assert_eq!(g_f, fermionic_single_pole(0.5, 5.0, 1.0).unwrap());

let g_b = gtau_single_pole::<Bosonic>(0.5, 5.0, 1.0).unwrap();
assert_eq!(g_b, bosonic_single_pole(0.5, 5.0, 1.0).unwrap());