gftool.fourier.tt2z_trapz
- gftool.fourier.tt2z_trapz(tt, gf_t, z)[source]
Laplace transform of the real-time Green’s function gf_t.
Approximate the Laplace integral by trapezoidal rule:
\[G(z) = ∫dt G(t) \exp(izt) ≈ ∑_{k=1}^N [G(t_{k-1})\exp(izt_{k-1}) + G(t_k)\exp(izt_k)] Δt_k/2\]The function can handle any input discretization tt.
- Parameters:
- tt(Nt) float np.ndarray
The points for which the Green’s function gf_t is given.
- gf_t(…, Nt) complex np.ndarray
Green’s function at time points tt.
- z(…, Nz) complex np.ndarray
Frequency points for which the Laplace transformed Green’s function should be evaluated.
- Returns:
- (…, Nz) complex np.ndarray
Laplace transformed Green’s function for complex frequencies z.
See also
tt2z_lin
Laplace integration using Filon’s method.
Notes
The function is equivalent to the one-liner np.trapz(np.exp(1j*z[:, None]*tt)*gf_t, x=tt). If numexpr is available, it is used for the significant speed up it provides for transcendental equations. Internally the sum is evaluated as a matrix product to leverage the speed-up of BLAS.