Feature/343 nystroem

[schroedk]

Description

This PR closes #343

Changes

• New method: NystroemSketchInfluence
• New property model_dtype of TorchInfluenceFunctionModel

Checklist

• Wrote Unit tests (if necessary)
• Updated Documentation (if necessary)
• Updated Changelog
• If notebooks were added/changed, added boilerplate cells are tagged with "tags": ["hide"] or "tags": ["hide-input"]

[Xuzzo]

Looks good to me. Maybe you could add an example on how to use Nystroem in the wine notebook. Right now the Arnoldi solver only shows the perc error, but you could add the correlation (like for ekfac) and then also do the same for Nystroem.

[schroedk]

Looks good to me. Maybe you could add an example on how to use Nystroem in the wine notebook. Right now the Arnoldi solver only shows the perc error, but you could add the correlation (like for ekfac) and then also do the same for Nystroem.

@Xuzzo I extended the wine notebook to show the usage for Nystroem, added also correlation and scatter plots for Arnoldi, Cg, Lissa.