gftool.basis.pole.PoleGf.from_moments

classmethod PoleGf.from_moments(moments, width=1.0)

Generate instance matching high-frequency moments.

Parameters:

moments(…, N) float array_like

Moments of the high-frequency expansion, where g(z) = moments / z**np.arange(1, N+1) for large z.

widthfloat or (…) float array_like or None, optional

Spread of the poles; they are in the interval [-width, width]. width=1 are the normal Chebyshev nodes in the interval [-1, 1]. If width=None and the second moment moments[…, 1] is given, the largest pole will match the second moment, unless it is small (abs(moments[…, 1]) < 0.1), then we choose width=1.

Returns:

PoleFct

Pole function with high-frequency moments.

See also

gf_from_moments

Contains the details how PoleFct is constructed.