Fixed:

• Fixed Windows installer to point to the new location for Ubuntu WSL images.

Fixed:

• Fixed pyproject.toml file for pixi 0.40.3.
• Updated installer to ship SageMath 10.5 and surface-dynamics 0.7.0.

Fixed:

• Fixd problems of installer with pixi 0.40.2 release on macOS by forcing a tested version of the pixi installer.

Fixed:

• Fixed "borrowed string" issues in installers.
• Fixed inconsistency in pixi.lock file.

Added:

• Added method SimplicialHomologyClass.chain() and examples that show how to rewrite a homology class into edges with multiplicities or into a holonomy vector.
• Added homology of saddle connections

Changed:

• Changed documentation to recommend conda over mamba (since mamba has been merged into essentially).

Fixed:

• Fixed a printing issues with surfaces containing 21-gons to 99-gons.
• Fixed printing of change_ring() surfaces.
• Fixed surface.change_ring().change_ring() to change the ring of the underlying surface instead of wrapping the surface twice.
• Fixed asssertion error when computing homology over the rationals.
• Fixed broken links in documentation (and added automatic checks for broken links).
• Fixed download instructions for "nightly build" installer.
• Fixed %pip and !conda in JupyterLab when launched from the installer
  (pip and conda are now installed into the dev environment).
• Fixed an UnboundLocalError in some saddle connection searches.
• Fixed "borrowing reference" error in all installers.

Fixed:

• Fixed flaky behavior upon first launch of JupyterLab on Windows 11.

Fixed:

• Fixed startup of SageMath on first invocation on Windows.

Added:

• Added methods angle(), edges(), edges_ccw(), and turns() for points of a surface.
• Added methods angles() for similarity surfaces and surfaces with boundary.
• Added is_in_edge_interior() and is_in_polygon_interior() for points of a surface.
• Added README to point out that our benchmarks are published at https://flatsurf.github.io/sage-flatsurf/asv/.
• Added installers for Linux, macOS, and Windows.
• Added homology() and cohomology() for surfaces; also exposed as SimplicialHomology() and SimplicialCohomology().
• Added area() for hyperbolic convex sets.
• Added angle() between hyperbolic geodesics.
• Added is_convex() for similarity surfaces to decide whether joining two polygons in a surface would lead to a convex polygon.
• Added join() for polygons, to glue two adjacent polygons into a single polygon.
• Added triangulate() method to Euclidean polygons.
• Added __getitem__() to all labels() so that accessing surface.labels()[i] is possible.
• Added is_triangulated(), is_delaunay_triangulated(), and is_delaunay_decomposed() for the infinite staircase.
• Added labels parameter to MutableOrientedSimilaritySurface.from_surface() to only copy part of an existing surface.
• Added a Tour of flatsurf to the documentation.
• Added VeechGroup and AffineAutomorphismGroup (also accessible as veech_gruop() and affine_automorphism_group() on surfaces.)
• Added apply_matrix() to all oriented similarity surfaces. (We apply the matrix to all polygons and keep the gluings intact. Probably not the most meaningful operation for non-dilation surfaces but it can be useful while building surfaces.)
• Added delaunay_triangulate() to similarity surfaces which returns a morphisms to a Delaunay triangulation of the surface.
• Added delaunay_decompose() to similarity surfaces which returns a morphisms to a Delaunay cell decomposition of the surface. This method always has an optional parameter codomain which can be an existing cell decomposition, this effectively exposes the isomorphism() function of a FlatTriangulation in libflatsurf.
• Added ngens() to homology to get the Betti number of homology.
• Added hom() for homology to produce the morphism in homology induced by a morphism of a surface or the morphism in homology given by a matrix.
• Added pyflatsurf() to translation surfaces to produce an isomorphic surface that is backed by libflatsurf (and exposes the underlying libflatsurf object in its flat_triangulation() method.)
• Added construction and test for veering triangulation of dilation surfaces
• Added random_flip for triangulated similarity surfaces

Changed:

• Changed the default development workflow. While you may still use conda/mamba for development, we recommend to use pixi instead, see the README for details.
• Renamed flatsurf.geometry.delaunay to flatsurf.geometry.lazy. (If for some reason you used this module directly, you need to update your imports.)
• Moved GL2RImageSurface from flatsurf.geometry.half_dilation_surface to flatsurf.geometry.lazy. (If for some reason you used this class directly, you need to update your imports.)
• Changed labels() and polygons() not to inherit from collections.abc.Set anymore. These are not just sets because their order matter, in particular, their order is compatible. However, edges() and gluings() are still collections.abc.Set.
• Changed relabel() on surfaces to default to relabeling to integer labels. Also the keyword parameter relabeling_map is now called relabeling.
• Changed apply_matrix(), it now returns a morphism to the deformed surface. To recover the old behavior, use apply_matrix().codomain().
• Changed triangle_flip() to now always turn the diagonal counterclockwise from the perspetive of label.
• Changed subdivide_edges(), it now returns a morphism to the surface with inserted vertices. To recover the old behavior, use subdivide_edges().codomain().

Deprecated:

• Deprecated return_adjacent_edges as a keyword argument to angles() since we do not want the type of a return value to fundamentally depend on the arguments.
• Deprecated triangulation with triangulate(in_place=True). There is no performance advantage in such a triangulation and it complicates future work on morphisms.
• Deprecated the limit keywords for is_triangulated, is_delaunay_triangulated, _is_*_surface, cmp. Querying infinite surfaces for properties up to a limit is often not very useful and at the same time the question can be answered trivially with knowledge of the surfaces. Also, this was implemented very inconsistently.
• Deprecated the singularity_limit keywords for to_surface. There is no replacement planned for this feature.
• Deprecated circumscribing_circle() of a polygon in favor of circumscribed_circle().
• Deprecated the test keyword of triangle_flip since there is already is_convex(strict=True).
• Deprecated delaunay_triangulation() in favor of delaunay_triangulate().
• Deprecated delaunay_decomposition() in favor of delaunay_decompose().
• Deprecated flatsurf.geometry.pyflatsurf_conversion module in favor of flatsurf.geometry.pyflatsurf.conversion.

Removed:

• Removed support for SageMath 9.4, 9.5, 9.6 (things might still work but we are not testing for it automatically anymore.)
• Removed the old flatsurf.geometry.relative_homology without prior deprecation (since it was not exposed publicly anywhere.) The new implementation should cover all the relevant features.
• Removed the ring keyword argument from GL2RImageSurface and GL2RMapping, the ring is now always the common parent of the surface base ring and the matrix base ring. (Use change_ring if you want the surface to live over another ring.)
• Removed the option in_place=True from delaunay_triangulation() and delaunay_decomposition(). There is no asymptotic runtime advantage in performing this operation in place (and we need to maintain two very different copies of the same functionality.)
• Removed the option triangulated=True from delaunay_triangulation() and delaunay_decomposition() since there is no significant runtime advantage in practice.
• Removed the option delaunay_triangulated=True from delaunay_decomposition() since there is no significant runtime advantage in practice.
• Removed the direction keyword from delaunay_triangulation() and delaunay_decomposition(). The claimed behavior about separatrices does not actually hold so the behavior here was somewhat random. Instead, we now always turn each edge counterclockwise when flipping.
• Removed local and limit parameters from rel_deformation(). The method is now backed by libflatsurf and should be much faster in practice.
• Removed the direction keyword of triangle_flip, veering_triangulation, l_infinity_delaunay_triangulation, delaunay_triangulation, and delaunay_decomposition since it was not clear what it actually did in general, instead the diagonal is now always turned counterclockwise.
• Removed support for SageMath 9.2 and 9.3. Virtually all of sage-flatsurf should still work with these versions but there are some inconsistencies in some homology outputs and we do not want to worry about it in our automated testing.

Fixed:

• Fixed an_element() and some_elements() of mutable surfaces.
• Fixed creation of points on the boundary of a surface.
• Fixed plotting of surfaces with boundary.
• Fixed caching of methods on mutable surfaces. Before edge_matrix() on a mutable surfaces was cached which could lead to wrong results.
• Fixed compatibility with SageMath 10.4.
• Fixed plotting in the reference manual. The module documentation now contain plots (when wrapped with jupyter-execute) instead of just saying Graphics object consisting of 18 graphics primitives.
• Fixed edges() of a hyperbolic polygon. The reported edges do now take into account marked vertices.
• Fixed rendering of formulas in documentation.
• Fixed ipyvue-flatsurf version installed with the flatsurf.yml environment so it is actually compatible with sage-flatsurf.
• Fixed installation instructions to include the Jupyter notebook which is mentioned there.
• Fixed comparison of infinite sets of labels. Labels can now be compared and hashed in some very limited cases.
• Fixed j_invariant() and erase_marked_points() they are now not available for infinite type surfaces anymore (where they failed before.)
• Fixed subdivide() and subdivide_polygons(); they now return immutable surfaces in the correct category.
• Fixed failing installation on macOS from flatsurf.yml.
• Fixed documentation on how to upgrade a mamba install of flatsurf.
• Fixed some rare compatibility issues when packages from conda-forge and anaconda get mixed up.
• Fixed name of project in setup.py. It's now sage-flatsurf instead of sage_flatsurf.
• Fixed documentation build to be compatible with SageMath 10.2 themeing.
• Fixed notification when docbuild is ready so it is less noisy, see sagemath/sage#37740.
• Fixed some pins in the flatsurf.yml that defines the flatsurf stack; upgraded SageMath to 10.2 and added pyintervalxt that had been missing.
• Fixed is_convex() for edges of surfaces. It does now allow this check for self-glued polygons.
• Fixed == and hashing for circles. Circles can now be used in dicts and sets.
• Fixed L^oo-Delaunay triangulation of dilation surfaces

Fixed:

• Fixed double escapes in sage-flatsurf version numbers.

Installer Linux & macOS & Windows (experimental)

Please provide feedback if this works or doesn't work for you :)

You can install the entire flatsurf stack if you are on Linux or macOS or on Windows.

For Windows, download the exe and follow the instructions.

For Linux and macOS, this does not make any changes to your system or user setup but just puts things into a self-contained directory. Download the pixi.tar.gz and run the following:

tar zxf sage-flatsurf-0.5.2.pixi.tar.gz
cd sage-flatsurf-0.5.2
PIXI_ARCH=x86_64 ./sage
./jupyterlab

Obsolete installers Linux & macOS

There is some older installers for Linux and macOS that are a bit more invasive and not recommended:

Download the corresponding .install below and copy it do a directory where you want to install flatsurf (the directory path must not contain whitespaces.) Then run

sh flatsurf-0.5.2-*.install
./flatsurf-0.5.2/flatsurf.run

This should open a Jupyter Lab in the current directory with SageMath and all of flatsurf pre-installed.

Added:

• Added get_point_position() for non-convex polygons.

Deprecated:

• Deprecated the translation keyword argument for get_point_position.

Fixed:

• Fixed angles() for half translation surfaces built with non-convex polygons
• Fixed triangulation of surfaces built from non-convex polygons.