0.7.1

Fixed:

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

0.7.0

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.

0.6.2

Fixed:

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

0.6.1

Fixed:

• Fixed startup of SageMath on first invocation on Windows.

0.6.0

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

0.5.2

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.

0.5.1

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.

0.5.0

How to Install/Upgrade

Quite a few things have changed in this release of sage-flatsurf. If you have been using sage-flatsurf before, you likely installed it through conda-forge. We recommend to initially keep your old version of sage-flatsurf around and install the latest release into a separate environment.

mamba env create -n flatsurf050 -f https://github.com/flatsurf/sage-flatsurf/raw/master/flatsurf.yml creates a new environment called flatsurf050. To activate it, use conda activate flatsurf050.

If you have never installed sage-flatsurf before, have a look at our installation guide here: https://flatsurf.github.io/sage-flatsurf/#installation

Release Notes

Added:

• Added example of how to check some conjectures by Boshernitzan to the documentation.
• Added point() on surfaces which contains the features of both, singularity() and surface_point(). (When passed a vertex id, it returns the point corresponding to that "singularity", when passed coordinates, it creates the point from the coordinates.)
• Added a hierarchy of surface categories, TopologicalSurfaces, PolygonalSurfaces, SimilaritySurfaces, DilationSurfaces, ConeSurfaces, TranslationSurfaces, HyperbolicSurfaces, and EuclideanPolygonalSurfaces together with axioms Connected, Orientable, Oriented, WithBoundary, WithoutBoundary, FiniteType, InfiniteType, Positive. These categories replace the existing hierarchy of SimilaritySurface, DilationSurface, HalfDilationSurface, TranslationSurface, HalfTranslationSurface, RationalConeSurface, RationalSimilaritySurface, ConeSurface. They serve essentially the same purpose, providing a place where to put functionality that applies to a certain kind of surface. However, this allows for more granularity, e.g., if some computation is only possible for translation surfaces of finite types, the method now lives in TranslationSurfaces.FiniteType and simply won't be available to surfaces that are of infinite type.
• Added a hierarchy of polygon categories, Polygons, HyperbolicPolygons, EuclideanPolygons and EuclideanPolygonsWithAngles together with axioms Convex, Rational, and Simple. These replace the existing differentiation between Polygon, ConvexPolygon and EquiangularPolygons.
• Added a labels() method to surfaces. This replaces the deprecated label_iterator() method. The object returned by labels() can (often) be efficiently queried for its len and decide containment.
• Added a polygons() method to surfaces. This essentially replaces the deprecated label_polygon_iterator() and label_iterator(polygons=True) method. The object returned by polygons() can be efficiently queried for its len so this also replaces the deprecated num_polygons.
• Added a roots() method to surfaces that returns labels from which iteration by labels() should start exploration of the connected components of a surface. There is also a root() method that returns the only such label on a connected surface.
• Added a is_finite_type() method to surfaces. This replaces the deprecated is_finite().
• Added an is_compact() method to surfaces that returns whether the surface is compact as a topological space.
• Added an is_connected() method to surfaces that returns whether the surface is connected as a topological space. (Before such surfaces were not well supported.)
• Added an is_with_boundary() method that returns whether a surface has polygons with unglued edges. (Before such surfaces were considered to be invalid now they are supported to some limited extent.)
• Added an euler_characteristic() method for surfaces of finite type.
• Added a change_ring() method to all surfaces to create a copy of the surface with polygons defined over a different base ring.
• Added a vertices() method to all surfaces built from polygons that returns the set of equivalence classes of vertices of those polygons.
• Added points of polygons as explicit objects (so that polygons become proper SageMath parents.) These points currently do not have many features.
• Added a describe_polygon() method to all polygons to create nicer textual representation of polygons for error messages.
• Added a is_degenerate() method to detect polygons with zero area or marked vertices.
• Added a marked_vertices keyword to vertices() of polygons to control whether vertices with angle π are included in the output.
• Added a erase_marked_vertices() method to polygons to produce a copy of the polygon without vertices with angle π.
• Added is_equilateral() and is_equiangular() methods to Euclidean polygons.
• Added a Pull Request Template on GitHub so we don't forget to write news or update the documentation.
• Added installation instructions to the documentation.
• Added HyperbolicPlane and plotting of hyperbolic objects. Unlike the implementation in SageMath, we do not rely on any symbolic computations.
• Added some convenience functions for SurfacePoint such as representatives(), representative(). Also ported over the methods from Singularity to SurfacePoint (though most are marked deprecated.)
• Added support for keyword arguments when plotting surfaces, e.g., plot(fill=None) prints polygons transparent for a similarity surface.
• Added polygon_options, edge_options, and vertex_options to control plotting in Polygon.plot().
• Added translation_surfaces.lanneau_nguyen_genus3_prototype() and translation_surfaces.lanneau_nguyen_genus4_prototype().
• Added Polygon.subdivide(), Surface.subdivide(), and SimilaritySurface.subdivide() to subdivide polygons into triangles centered at the centroid of the convex polygons.
• Added Polygon.subdivide_edges(), Surface.subdivide_edges(), and SimilaritySurface.subdivide_edges() to add equally spaced marked points along the edges of polygons.
• Added Polygon.centroid() to compute the geometric center of polygons.
• Added plot() method for tangent vectors.

Changed:

• Changed supported versions of SageMath. We now require at least SageMath 9.2 (released in October 2020.)
• Changed the notion of "dilation surface" in some places. What was previously called a "half-dilation surface" is now called a "dilation surface", and what was previously called a "dilation surface" is now called a "positive dilation surface". (Existing code should not be affected by this but the documentation has been updated and new functions use this naming.) Note that the notions of a half-translation surface and a translation surface have not changed (though internally a translation surface is just a positive half-translation surface.)
• Changed the mutability of the surface returned by polyhedron_to_cone_surface; the returned surface is now immutable.
• Changed the mutability of methods taking an in_place keyword argument. These methods now consistentlny return an immutable surface when in_place is False.
• Changed Polygon in flatsurf.geometry.polygon; it has been renamed to EuclideanPolygon. Polygon() is now a factory function that creates an euclidean polygon, compatible with the way that polygons() used to create such a polygon.
• Changed the structure of hyperbolic sets. Points are now SageMath elements of their parent, the hyperbolic plane. Other sets are now (facade) parents. This change allows us to bring hyperbolic convex polygons as parents into the category of polygons. So, hyperbolic polygons and Euclidean polygons are on a similar footing and we can (eventually) build surfaces from both of them in the same way.
• Renamed flatsurf.geometry.matrix_2x2 to flatsurf.geometry.euclidean and moved more geometry helpers there.
• Changed placement and naming of some geometry helper functions. For example, unified is_parallel and is_same_direction, renamed is_opposite_direction to is_anti_parallel (and simplified implementation), renamed wedge_product to ccw and renamed wedge to wedge_product. Most of these now live in flatsurf.geometry.euclidean.
• Changed the label parameter of add_polygon(). It is now required to be a keyword argument.
• Changed the meaning of the lengths parameter when creating a polygon from lengths and angles. Before, the slopes of a generic polygon with such angles were scaled by lengths (the slopes are a somewhat random implementation detail.) Now, the lengths are actually, the Euclidean lengths of the sides. Specifying lengths and angles might therefore lead to some square roots having to be computed. To get the old behaviour, one can specify angles and edges and use the slopes scaled by lengths as edges.
• Changed the documentation build to use the furo theme for sphinx, the same theme that SageMath uses for its documentation.
• The parameter limit for SurfacePoint and Singularity is now optional. If not given for infinite surfaces, the search will keep going until the object has been constructed.
• Changed how points print. Instead of Surface point with n coordinate representations, points now print as one of these coordinate representations.
• Changed == of surfaces in some limited cases. Equality now means more strictly that surfaces are indistinguishable. For example, a mutable surface is now always distinct from an immutable surface.

Deprecated:

• Deprecated the walker() method on surfaces. The labels() are now always guaranteed to be iterated in a canonical order (starting from the roots(), a breadth-first search is performed.)
• Deprecated the base_label() method on surfaces. The root() and roots() methods serve the same purpose but have clearer semantics for disconnected surfaces.
• Deprecated the...

0.4.7

Performance:

• SimilaritySurface.edge_matrix becomes a cached_method

Removed:

• Removed unused functions from matrix_2x2, namely, number_field_to_AA,
  homothety_rotation_decomposition, is_similarity, rotation_matrix_angle.

0.4.6

Performance:

• Improved acting with a matrix on a polygon by not checking convexity of the result.