gftool.pade.coefficients

gftool.pade.coefficients(z, fct_z) → ndarray

Calculate the coefficients for the Padé continuation.

Parameters:

z(N_z, ) complex ndarray

Array of complex points.

fct_z(…, N_z) complex ndarray

Function at points z.

Returns:

(…, N_z) complex ndarray

Array of Padé coefficients, needed to perform Padé continuation. Has the same same shape as fct_z.

Raises:

ValueError

If the size of z and the last dimension of fct_z do not match.

Notes

The calculation is always done in quad precision (complex256), as it is very sensitive towards rounding errors. Afterwards the type of the result is cast back to double precision (complex128) unless the input data of fct_z was already quad precision {float128, complex256}, see _PRECISE_TYPES. This avoids giving the illusion that the results are more precise than the input.