triqs.gfs.tools.fit_legendre

triqs.gfs.tools.fit_legendre(g_t, order=10)[source]

Fit a (possibly noisy) imaginary-time Green’s function to a Legendre expansion.

Parameters:

g_tGf or BlockGf: Matrix-valued imaginary-time Green’s function (typically the binned output of a QMC solver).
orderint, optional: Maximal order of the Legendre expansion (number of coefficients used). Default 10.

Returns:

Gf or BlockGf: Legendre Green’s function with order coefficients.

Notes

Only Hermiticity is imposed during the fit; discontinuities at \(\tau = 0^+\) and \(\tau = \beta^-\) must be enforced separately via triqs.gfs.enforce_discontinuity().

Original author: Hugo U.R. Strand.