Open YannIntVeld opened 2 months ago
Dear @YannIntVeld
The behavior you describe is actually expected.
The DLR representation is not suited for Green functions that do not have a spectral representation, e.g. a constant function.
We should however make this more clear in our documentation.
Dear @Wentzell
Ah, I see that makes a lot of sense. Thanks a lot for the clarification.
Description
When interpolating a constant Green's function (eg.. $G(i\omega_n) = U$) on a DLR mesh, the resulting error is larger than the representation accuracy given to the DLR mesh constructor.
This issue also occurs for DLR Green's functions which have frequency structure, but with a high-frequency offset.
Steps to Reproduce
The following minimal example will reproduce the problem
The resulting plot is
Expected behavior: The error $G(i\omega_n) - U$ to be smaller than the value of
dlreps
.Actual behavior: The error $G(i\omega_n) - U$ is larger than
dlreps
.