[WIP] Wasserstein distance on the circle and Spherical Sliced-Wasserstein (#434)

* W circle + SSW

* Tests + Example SSW_1

* Example Wasserstein Circle + Tests

* Wasserstein on the circle wrt Unif

* Example SSW unif

* pep8

* np.linalg.qr for numpy < 1.22 by batch + add python3.11 to tests

* np qr

* rm test python 3.11

* update names, tests, backend transpose

* Comment error batchs

* semidiscrete_wasserstein2_unif_circle example

* torch permute method instead of torch.permute for previous versions

* update comments and doc

* doc wasserstein circle model as [0,1[

* Added ot.utils.get_coordinate_circle to get coordinates on the circle in turn

1 files changed, 9 insertions, 1 deletions

diff --git a/README.md b/README.md
index 7c9475b..d5e6854 100644
--- a/README.md
+++ b/README.md
@@ -39,6 +39,8 @@ POT provides the following generic OT solvers (links to examples):
 * [Partial Wasserstein and Gromov-Wasserstein](https://pythonot.github.io/auto_examples/unbalanced-partial/plot_partial_wass_and_gromov.html) (exact [29] and entropic [3]
   formulations).
 * [Sliced Wasserstein](https://pythonot.github.io/auto_examples/sliced-wasserstein/plot_variance.html) [31, 32] and Max-sliced Wasserstein [35] that can be used for gradient flows [36].
+* [Wasserstein distance on the circle](https://pythonot.github.io/auto_examples/plot_compute_wasserstein_circle.html) [44, 45]
+* [Spherical Sliced Wasserstein](https://pythonot.github.io/auto_examples/sliced-wasserstein/plot_variance_ssw.html) [46]
 * [Graph Dictionary Learning solvers](https://pythonot.github.io/auto_examples/gromov/plot_gromov_wasserstein_dictionary_learning.html) [38].
 * [Several backends](https://pythonot.github.io/quickstart.html#solving-ot-with-multiple-backends) for easy use of POT with  [Pytorch](https://pytorch.org/)/[jax](https://github.com/google/jax)/[Numpy](https://numpy.org/)/[Cupy](https://cupy.dev/)/[Tensorflow](https://www.tensorflow.org/) arrays.
 
@@ -292,4 +294,10 @@ Dictionary Learning](https://arxiv.org/pdf/2102.06555.pdf), International Confer
 
 [42] Delon, J., Gozlan, N., and Saint-Dizier, A. [Generalized Wasserstein barycenters between probability measures living on different subspaces](https://arxiv.org/pdf/2105.09755). arXiv preprint arXiv:2105.09755, 2021.
 
-[43]  Álvarez-Esteban, Pedro C., et al. [A fixed-point approach to barycenters in Wasserstein space.](https://arxiv.org/pdf/1511.05355.pdf) Journal of Mathematical Analysis and Applications 441.2 (2016): 744-762.
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+[43]  Álvarez-Esteban, Pedro C., et al. [A fixed-point approach to barycenters in Wasserstein space.](https://arxiv.org/pdf/1511.05355.pdf) Journal of Mathematical Analysis and Applications 441.2 (2016): 744-762.
+
+[44] Delon, Julie, Julien Salomon, and Andrei Sobolevski. [Fast transport optimization for Monge costs on the circle.](https://arxiv.org/abs/0902.3527) SIAM Journal on Applied Mathematics 70.7 (2010): 2239-2258.
+
+[45] Hundrieser, Shayan, Marcel Klatt, and Axel Munk. [The statistics of circular optimal transport.](https://arxiv.org/abs/2103.15426) Directional Statistics for Innovative Applications: A Bicentennial Tribute to Florence Nightingale. Singapore: Springer Nature Singapore, 2022. 57-82.
+
+[46] Bonet, C., Berg, P., Courty, N., Septier, F., Drumetz, L., & Pham, M. T. (2023). [Spherical Sliced-Wasserstein](https://openreview.net/forum?id=jXQ0ipgMdU). International Conference on Learning Representations.
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