triqs.gfs.gf.Gf.fit_tail_on_window

Gf.fit_tail_on_window(*args, **kw)

Dispatched C++ function(s).

[1] (g: Gf[MeshImFreq, 2],
     n_min: int,
     n_max: int,
     known_moments: ndarray[complex, 3],
     n_tail_max: int,
     expansion_order: int)
  -> tuple[ndarray[complex, 3], float]

Fit the high-frequency tail of a Matsubara Green’s function on a restricted frequency window.

The fit is performed on the window \([n_{\min}, n_{\max}]\) of the Matsubara mesh (\(n_{\max} = -1\) selects the last index of the mesh). The tail fitter is configured from n_tail_max and expansion_order, and the fit is delegated to fit_tail.

Parameters:

gGf[MeshImFreq, 2]

The Matsubara Green’s function whose tail is to be fitted.

n_minint

Minimum Matsubara index of the fit window.

n_maxint

Maximum Matsubara index of the fit window (\(-1\) means use the last index of the mesh).

known_momentsndarray[complex, 3]

Array of known high-frequency moments to constrain the fit.

n_tail_maxint

Maximum frequency index used internally by the tail fitter.

expansion_orderint

Order of the tail expansion to fit.

Returns:

tuple[ndarray[complex, 3], float]

A pair containing the fitted tail moments and the fitting error.