gftool.pade.coefficients

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

Calculate the coefficients for the Pade continuation.

Parameters

z(N_z, ) complex ndarray

Array of complex points

fct_z(…, N_z) complex ndarray

Function at points z

Returns

coefficients(…, N_z) complex ndarray

Array of Pade coefficients, needed to perform Pade 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.