wiseodd / curvlinops

scipy linear operators for the Hessian, Fisher/GGN, and more in PyTorch

scipy linear operators of deep learning matrices in PyTorch

This library implements scipy.sparse.linalg.LinearOperators for deep learning matrices, such as

• the Hessian
• the Fisher/generalized Gauss-Newton (GGN)
• the Monte-Carlo approximated Fisher
• the Fisher/GGN's KFAC approximation (Kronecker-Factored Approximate Curvature)
• the uncentered gradient covariance (aka empirical Fisher)
• the output-parameter Jacobian of a neural net and its transpose

Matrix-vector products are carried out in PyTorch, i.e. potentially on a GPU. The library supports defining these matrices not only on a mini-batch, but on data sets (looping over batches during a matvec operation).

You can plug these linear operators into scipy, while carrying out the heavy lifting (matrix-vector multiplies) in PyTorch on GPU. My favorite example for such a routine is scipy.sparse.linalg.eigsh that lets you compute a subset of eigen-pairs.

The library also provides linear operator transformations, like taking the inverse (inverse matrix-vector product via conjugate gradients) or slicing out sub-matrices.

Finally, it offers functionality to probe properties of the represented matrices, like their spectral density, trace, or diagonal.

• Documentation: https://curvlinops.readthedocs.io/en/latest/

• Bug reports & feature requests: https://github.com/f-dangel/curvlinops/issues

Installation

pip install curvlinops-for-pytorch

Examples

• Basic usage
• Advanced examples

Future ideas

Other features that could be supported in the future include:

• Other matrices

  • the centered gradient covariance
  • terms of the hierarchical GGN decomposition

Logo mage credits

• SciPy logo: Unknown, CC BY-SA 4.0, via Wikimedia Commons
• PyTorch logo: https://github.com/soumith, CC BY-SA 4.0, via Wikimedia Commons