Sage 9.4 Release Tour
released Aug 22, 2021
Contents

Sage 9.4 Release Tour
 Symbolics
 Convex geometry
 Knot theory

Manifolds
 Unicode characters for various symbols in plain text outputs
 Specifying coordinate restrictions while declaring a new chart
 Defining submanifolds and manifold subsets by pullbacks from Sage sets
 Manifold options for RealSet constructors
 Families and posets of manifold subsets
 New method for constructing a tangent vector
 De Rham cohomology
 Internal code improvements and bug fixes
 Coding theory
 Algebra
 Hyperbolic geometry
 Configuration changes
 Package upgrades
 For developers and packagers: Refactoring, modernization, and modularization
 Availability of Sage 9.4 and installation help
 More details
Symbolics
Extended interface with SymPy
The SymPy package has been updated to version 1.8.
SageMath has a bidirectional interface with SymPy. Symbolic expressions in Sage provide a _sympy_ method, which converts to SymPy; also, Sage attaches _sage_ methods to various SymPy classes, which provide the opposite conversion.
In Sage 9.4, several conversions have been added. Now there is a bidirectional interface as well for matrices and vectors. #31942
sage: M = matrix([[sin(x), cos(x)], [cos(x), sin(x)]]); M [ sin(x) cos(x)] [cos(x) sin(x)] sage: sM = M._sympy_(); sM Matrix([ [ sin(x), cos(x)], [cos(x), sin(x)]]) sage: sM.subs(x, pi/4) # computation in SymPy Matrix([ [ sqrt(2)/2, sqrt(2)/2], [sqrt(2)/2, sqrt(2)/2]])
Work is underway to make SymPy's symbolic linear algebra methods available in Sage via this route.
Callable symbolic expressions, such as those created using the Sage preparser's f(...) = ... syntax, now convert to a SymPy Lambda. #32130
sage: f(x, y) = x^2 + y^2; f (x, y) > x^2 + y^2 sage: f._sympy_() Lambda((x, y), x**2 + y**2)
Sage has added a formal set membership function element_of for use in symbolic expressions; it converts to a SymPy's Contains expression. #24171
Moreover, all sets and algebraic structures (Parents) of SageMath are now accessible to SymPy by way of a wrapper class SageSet, which implements the SymPy Set API. #31938
sage: F = Family([2, 3, 5, 7]); F Family (2, 3, 5, 7) sage: sF = F._sympy_(); sF SageSet(Family (2, 3, 5, 7)) # this is how the wrapper prints sage: sF._sage_() is F True # bidirectional sage: bool(sF) True sage: len(sF) 4 sage: sF.is_finite_set # SymPy property True
Finite or infinite, we can wrap it:
sage: W = WeylGroup(["A",1,1]) sage: sW = W._sympy_(); sW SageSet(Weyl Group of type ['A', 1, 1] (as a matrix group acting on the root space)) sage: sW.is_finite_set False sage: sW.is_iterable True sage: sB3 = WeylGroup(["B", 3])._sympy_(); sB3 SageSet(Weyl Group of type ['B', 3] (as a matrix group acting on the ambient space)) sage: len(sB3) 48
Some parents or constructions have a more specific conversion to SymPy. #31931, #32015
sage: ZZ3 = cartesian_product([ZZ, ZZ, ZZ]) sage: sZZ3 = ZZ3._sympy_(); sZZ3 ProductSet(Integers, Integers, Integers) sage: (1, 2, 3) in sZZ3 sage: NN = NonNegativeIntegers() sage: NN._sympy_() Naturals0 sage: (RealSet(1, 2).union(RealSet.closed(3, 4)))._sympy_() Union(Interval.open(1, 2), Interval(3, 4)) sage: X = Set(QQ).difference(Set(ZZ)); X Settheoretic difference of Set of elements of Rational Field and Set of elements of Integer Ring sage: X._sympy_() Complement(Rationals, Integers) sage: X = Set(ZZ).difference(Set(QQ)); X Settheoretic difference of Set of elements of Integer Ring and Set of elements of Rational Field sage: X._sympy_() EmptySet
See Metaticket #31926: Connect Sage sets to SymPy sets
ConditionSet
Sage 9.4 introduces a class ConditionSet for subsets of a parent (or another set) consisting of elements that satisfy the logical "and" of finitely many predicates. #32089
sage: in_small_oblong(x, y) = x^2 + 3 * y^2 <= 42 sage: SmallOblongUniverse = ConditionSet(QQ^2, in_small_oblong) sage: SmallOblongUniverse { (x, y) ∈ Vector space of dimension 2 over Rational Field : x^2 + 3*y^2 <= 42 } sage: parity_check(x, y) = abs(sin(pi/2*(x + y))) < 1/1000 sage: EvenUniverse = ConditionSet(ZZ^2, parity_check); EvenUniverse { (x, y) ∈ Ambient free module of rank 2 over the principal ideal domain Integer Ring : abs(sin(1/2*pi*x + 1/2*pi*y)) < (1/1000) } sage: SmallOblongUniverse & EvenUniverse { (x, y) ∈ Free module of degree 2 and rank 2 over Integer Ring Echelon basis matrix: [1 0] [0 1] : x^2 + 3*y^2 <= 42, abs(sin(1/2*pi*x + 1/2*pi*y)) < (1/1000) }
The name ConditionSet is borrowed from SymPy. In fact, if the given predicates (condition) are symbolic, a ConditionSet can be converted to a SymPy ConditionSet; the _sympy_ method falls back to creating a SageSet wrapper otherwise.
symbolic_expression(lambda x, y: ...)
Sage 9.4 has added a new way to create callable symbolic expressions. #32103
The global function symbolic_expression now accepts a callable such as those created by lambda expressions. The result is a callable symbolic expression, in which the formal arguments of the callable are the symbolic arguments.
Example:
symbolic_expression(lambda x,y: x^2+y^2) == (SR.var("x")^2 + SR.var("y")^2).function(SR.var("x"), SR.var("y"))
This provides a convenient syntax in particular in connection to ConditionSet.
Instead of
sage: predicate(x, y, z) = sqrt(x^2 + y^2 + z^2) < 12 # preparser syntax, creates globals sage: ConditionSet(ZZ^3, predicate)
one is now able to write
sage: ConditionSet(ZZ^3, symbolic_expression(lambda x, y, z: ....: sqrt(x^2 + y^2 + z^2) < 12))
Convex geometry
ABC for convex sets
Sage 9.4 has added an abstract base class ConvexSet_base (as well as abstract subclasses ConvexSet_closed, ConvexSet_compact, ConvexSet_relatively_open, ConvexSet_open) for convex subsets of finitedimensional real vector spaces. The abstract methods and default implementations of methods provide a unifying API to the existing classes Polyhedron_base, ConvexRationalPolyhedralCone, LatticePolytope, and PolyhedronFace. #31919, #31959, #31990, #31993
Several methods previously only available for Polyhedron_base instances, are now available for all convex sets. The method an_affine_basis returns a sequence of points that span by affine linear combinations the affine hull, i.e., the smallest affine subspace in which the convex set lies. The method affine_hull returns the latter as a polyhedron. The method affine_hull_projection (renamed from affine_hull in Sage 9.1) computes an affine linear transformation of the convex set to a new ambient vector space, in which the image is fulldimensional. The generalized method also provides additional data: the right inverse (section map) of the projection. #27366, #31963, #31993
As part of the ConvexSet_base API, there are new methods for pointset topology such as is_open, relative_interior, and closure. For example, taking the relative_interior of a polyhedron constructs an instance of RelativeInterior, a simple object that provides a __contains__ method and all other methods of the ConvexSet_base API. #31916
sage: P = Polyhedron(vertices=[(1,0), (1,0)]) sage: ri_P = P.relative_interior(); ri_P Relative interior of a 1dimensional polyhedron in ZZ^2 defined as the convex hull of 2 vertices sage: (0, 0) in ri_P True sage: (1, 0) in ri_P False
ConvexSet_base is a subclass of the new abstract base class Set_base. #32013
This makes various methods that were previously only defined for sets constructed using the Set constructor available for polyhedra and other convex sets. As an example, we can now do:
sage: polytopes.cube().union(polytopes.tetrahedron()) Settheoretic union of Set of elements of A 3dimensional polyhedron in ZZ^3 defined as the convex hull of 8 vertices and Set of elements of A 3dimensional polyhedron in ZZ^3 defined as the convex hull of 4 vertices
New operations on faces of convex polyhedra
PolyhedronFace has a new method affine_tangent_cone. #29811
sage: c = polytopes.cube() sage: edge = min(c.faces(1)) sage: edge.vertices() (A vertex at (1, 1, 1), A vertex at (1, 1, 1)) sage: T_edge = edge.affine_tangent_cone() sage: T_edge.Vrepresentation() (A line in the direction (0, 1, 0), A ray in the direction (0, 0, 1), A vertex at (1, 0, 1), A ray in the direction (1, 0, 0))
Sage 9.4 also defines two new Polyhedron_base methods that look up a face in the face lattice of a polyhedron. #29683
meet_of_Vrep (alias: least_common_superface_of_Vrep) finds the smallest face containing specified Vrepresentatives
join_of_Hrep (alias: greatest_common_subface_of_Hrep) finds the largest face contained specified facets
Parallel face iterator
The fvector of polyhedra is now computed in parallel on many platforms.
For developers: This is done with a parallel face iterator. Instead of just counting the faces, one can also perform different operations in parallel.
Polyhedral complexes
Sage 9.4 defines a new subclass of GenericCellComplex for (geometric) polyhedral complexes, PolyhedralComplex #31748
sage: pc = PolyhedralComplex([ ....: Polyhedron(vertices=[(1/3, 1/3), (0, 0), (1/7, 2/7)]), ....: Polyhedron(vertices=[(1/7, 2/7), (0, 0), (0, 1/4)])]) sage: [p.Vrepresentation() for p in pc.cells_sorted()] [(A vertex at (0, 0), A vertex at (0, 1/4), A vertex at (1/7, 2/7)), (A vertex at (0, 0), A vertex at (1/3, 1/3), A vertex at (1/7, 2/7)), (A vertex at (0, 0), A vertex at (0, 1/4)), ... (A vertex at (1/7, 2/7),), (A vertex at (1/3, 1/3),)] sage: pc.plot() Graphics object consisting of 10 graphics primitives sage: pc.is_pure() True sage: pc.is_full_dimensional() True sage: pc.is_compact() True sage: pc.boundary_subcomplex() Polyhedral complex with 4 maximal cells sage: pc.is_convex() True sage: pc.union_as_polyhedron().Hrepresentation() (An inequality (1, 4) x + 1 >= 0, An inequality (1, 1) x + 0 >= 0, An inequality (1, 0) x + 0 >= 0) sage: pc.face_poset() Finite poset containing 11 elements sage: pc.is_connected() True sage: pc.connected_component() == pc True
The homogeneous analogue to a polyhedral complex is a polyhedral fan. The constructor Fan for instances of the class RationalPolyhedralFan has been generalized: If the new keyword allow_arrangement=True is passed, the input is allowed to be an arbitrary finite set (arrangement) of rational polyhedral cones; Sage then computes a suitable common refinement that is a fan. #25122
More details
Some smaller improvements that are listed in the release notes for optimization and polyhedral geometry software interactions in Sage.
Knot theory
Databases
A direct access to the contents of the KnotInfo and LinkInfo databases is available as an optional Sage package, now (see Trac #30352). It can be installed via
sage i database_knotinfo
For example, you can obtain the Kauffman polynomial of a link via these databases which has no implementation in Sage, so far:
sage: B = BraidGroup(8) sage: L = Link(B([1, 1, 1, 2, 1, 2, 3, 2, 3])) sage: K, mirrored = L.get_knotinfo(); K, mirrored (<KnotInfo.K8_14: '8_14'>, True) sage: K.kauffman_polynomial() z^4 + 2*a^1*z^5 + 2*a^2*z^6 + a^3*z^7  2*z^2  3*a^1*z^3  a^2*z^4 + 3*a^3*z^5 + 5*a^4*z^6 + a^5*z^7 + 1 + a^1*z  a^2*z^2  6*a^3*z^3  7*a^4*z^4 + 4*a^5*z^5 + 3*a^6*z^6 + 3*a^3*z + 3*a^4*z^2  8*a^5*z^3  4*a^6*z^4 + 3*a^7*z^5 + 3*a^5*z + a^6*z^2  5*a^7*z^3 + a^8*z^4 + a^7*z  a^8*z^2
See also the reference manual.
Testing isotopy
There is a new method is_isotopic which allows to check if two links are isotopic to each other:
sage: l1 = Link([[2, 9, 3, 10], [4, 13, 5, 14], [6, 11, 7, 12], ....: [8, 1, 9, 2], [10, 7, 11, 8], [12, 5, 13, 6], ....: [14, 3, 1, 4]]) sage: l2 = Link([[1, 8, 2, 9], [9, 2, 10, 3], [3, 14, 4, 1], ....: [13, 4, 14, 5], [5, 12, 6, 13], [11, 6, 12, 7], ....: [7, 10, 8, 11]]) sage: l1 == l2 False sage: l1.is_isotopic(l2) True sage: l3 = l2.mirror_image() sage: l1.is_isotopic(l3) False
Manifolds
The full list of changes is available in this changelog.
Unicode characters for various symbols in plain text outputs
In plain text mode, various symbols are now displayed by means of Unicode characters instead of ASCII workarounds (#30473). This regards
 arrows for maps on manifolds:
sage: M = Manifold(2, 'M') sage: X.<x,y> = M.chart() sage: M.identity_map().display() Id_M: M → M (x, y) ↦ (x, y) sage: f = M.scalar_field(x^2 + y^2, name='f') sage: f.display() f: M → ℝ (x, y) ↦ x^2 + y^2
 partial derivatives for coordinate vector fields:
sage: v = M.vector_field(y, x, name='v') sage: v.display() v = y ∂/∂x + x ∂/∂y sage: X.frame() Coordinate frame (M, (∂/∂x,∂/∂y))
 circled times for tensor products:
sage: (v*diff(f)).display() v⊗df = 2*x*y ∂/∂x⊗dx  2*y^2 ∂/∂x⊗dy + 2*x^2 ∂/∂y⊗dx + 2*x*y ∂/∂y⊗dy
 wedge symbol for exterior products:
sage: v.wedge(X.frame()[0]).display() v∧∂/∂x = x ∂/∂x∧∂/∂y
Specifying coordinate restrictions while declaring a new chart
The manifold method chart has been endowed with the new argument coord_restrictions, allowing to define conditions restricting the range of coordinates (#32102). For instance to define a half disk above the diagonal x+y=0:
sage: M = Manifold(2, 'M') sage: X.<x,y> = M.chart(coord_restrictions=lambda x,y: [x^2+y^2<1, x+y>0]) sage: X.plot(max_range=1, number_values=41)
Previously, to achieve the same result, one had to invoke X.add_restrictions([x^2+y^2<1, x+y>0]) after the declaration of the chart X. The method add_restrictions is now deprecated.
Defining submanifolds and manifold subsets by pullbacks from Sage sets
Given a continuous map Φ from a topological or differentiable manifold N and a subset S of the codomain of Φ, we define the pullback (preimage) of S as the subset of N of points p with Φ(p) in S. #31688
Generically, such pullbacks are represented by instances of the new class ManifoldSubsetPullback. But because Φ is continuous, topological closures and interiors pull back accordingly. Hence, in some cases we are able to give the pullback additional structure, such as creating a submanifold rather than merely a manifold subset.
In addition to the case when Φ is a continuous map between manifolds, there are two situations that connect Sage manifolds to sets defined by other components of Sage:
If Φ: N > R is a real scalar field, then any RealSet S (i.e., a finite union of intervals) can be pulled back.
If Φ is a chart – viewed as a continuous function from the chart's domain to R^n – then any subset of R^n can be pulled back to define a manifold subset. This can be a polyhedron, a lattice, a linear subspace, a finite set, or really any object with a __contains__ method.
 For example, defining a "chart polyhedron" by pulling back a polyhedron:
sage: M = Manifold(2, 'R^2', structure='topological') sage: c_cart.<x,y> = M.chart() # Cartesian coordinates on R^2 sage: P = Polyhedron(vertices=[[0, 0], [1, 2], [2, 1]]); P A 2dimensional polyhedron in ZZ^2 defined as the convex hull of 3 vertices sage: McP = c_cart.preimage(P); McP Subset x_y_inv_P of the 2dimensional topological manifold R^2 sage: M((1, 2)) in McP True sage: M((2, 0)) in McP False
Pulling back the interior of a polytope under a chart:sage: int_P = P.interior(); int_P Relative interior of a 2dimensional polyhedron in ZZ^2 defined as the convex hull of 3 vertices sage: McInt_P = c_cart.preimage(int_P, name='McInt_P'); McInt_P Open subset McInt_P of the 2dimensional topological manifold R^2 sage: M((0, 0)) in McInt_P False sage: M((1, 1)) in McInt_P True
 For example, defining a "chart polyhedron" by pulling back a polyhedron:
In a similar direction, the new method ConvexSet_base.affine_hull_manifold makes the affine hull of a convex set available as a Riemannian submanifold embedded into the ambient Euclidean space. #31659
Manifold options for RealSet constructors
As an application of chart pullbacks, the RealSet constructors have been extended so that they can optionally build manifolds or manifolds subsets. #31881
This is activated by passing the manifold keyword structure='differentiable':
sage: RealSet(oo, oo, structure='differentiable') Real number line ℝ sage: RealSet([0, 1], structure='differentiable') Subset [0, 1] of the Real number line ℝ
It is also implied when a coordinate name is given using the keyword coordinate:
sage: RealSet(0, 1, coordinate='λ') Open subset (0, 1) of the Real number line ℝ sage: _.category() Join of Category of smooth manifolds over Real Field with 53 bits of precision and Category of connected manifolds over Real Field with 53 bits of precision and Category of subobjects of sets
It is also implied by assigning a coordinate name using generator notation:
sage: R_xi.<ξ> = RealSet.real_line(); R_xi Real number line ℝ sage: R_xi.canonical_chart() Chart (ℝ, (ξ,))
The above example showed the use of the new constructor RealSet.real_line. The manifold keywords work for all other specialized constructors for various types of intervals, as well.
Constructor 
Interval 

RealSet.open 
(a, b) 

RealSet.closed 
[a, b] 

RealSet.point 
{a} 

RealSet.open_closed 
(a, b] 

RealSet.closed_open 
[a, b) 

RealSet.unbounded_below_closed 
(oo, b] 

RealSet.unbounded_below_open 
(oo, b) 

RealSet.unbounded_above_closed 
[a, +oo) 

RealSet.unbounded_above_open 
(a, +oo) 

RealSet.real_line 
(oo, +oo) 
new in Sage 9.4 
RealSet.interval 
any 
new in Sage 9.4 
The global bindings RealLine and OpenInterval, which create manifolds, are now deprecated, but these constructors will remain available through the manifolds catalog, via manifolds.RealLine and manifolds.OpenInterval. The objects made by these constructors are now also valid input for RealSet. #30832
Families and posets of manifold subsets
In Sage 9.4, the system for declaring (named) subsets of topological and differentiable manifolds has become more general and powerful.
In addition to declare_union and declare_intersection, there are now methods declare_empty, declare_nonempty, declare_subset, declare_superset, and declare_equal.
The declared subset relations define a quasiorder on the named subsets. To visualize the subset relations, methods subset_digraph and superset_digraph are now available.
Through a sequence of subset declarations, or directly through declare_equal, several named subsets (which are distinct as Python objects) can become necessarily equal as mathematical sets. By quotienting out by this equivalence relation, we obtain a partially ordered set, which is available through the new methods subset_poset and superset_poset.
The new class ManifoldSubsetFiniteFamily serves as a container for storing arbitrary finite families of manifold subsets, indexed by their names. The new methods subset_family, superset_family, and open_superset_family return instances of ManifoldSubsetFiniteFamily. Such instances are automatically sorted by name, are hashable, compare with each other lexicographically, and print more compactly than lists/tuples/sets of manifold subsets.
For more information, see Metaticket #31740.
New method for constructing a tangent vector
Manifolds have been endowed with the method tangent_vector (shortcut alias vector) for the direct construction of a tangent vector at a given point (#31609):
sage: M = Manifold(2, 'M') sage: X.<x,y> = M.chart() sage: p = M((1, 2), name='p') sage: v = M.tangent_vector(p, 1, 3); v Tangent vector at Point p on the 2dimensional differentiable manifold M sage: v.display() ∂/∂x + 3 ∂/∂y
Previously, tangent vectors could only be constructed as elements of the tangent space at the given point:
sage: Tp = M.tangent_space(p) sage: v = Tp((1, 3))
De Rham cohomology
De Rham cohomology has been implemented via the new classes DeRhamCohomologyRing and DeRhamCohomologyClass; the algebra of mixed differential forms has been turned into a de Rham complex (#31691)
Internal code improvements and bug fixes
Various improvements/refactoring of the code have been performed in this release:
In addition, various bugs have been fixed: #31784, #31904, #31923, #32112.
Coding theory
AG codes
Algebraic geometry codes (shortly AG codes) and their decoders are now available in Sage 9.4 (see #27957).
It is first time that all AG codes as originally defined by Goppa in 1981 are equipped with an efficient decoding algorithm implemented in free software. This has become possible when global function fields machinery was implemented in Sage 8. Most famous error correcting codes such as ReedSolomon codes and Goppa codes (the workhorse of the McEliece cryptosystem which is a candidate of the NIST standardization process for postquantum cryptography) are special cases of AG codes.
A user should be warned that creating a decoder for a long AG code may take a long time, but decoding with the created decoder should be quick.
sage: F.<a> = GF(64) sage: A1 = AffineSpace(F,1) sage: C = Curve(A1) sage: C Affine Line over Finite Field in a of size 2^6 sage: pls = C.places() sage: Q, = C.places_at_infinity() sage: pls.remove(Q) sage: code = codes.EvaluationAGCode(pls, 31*Q) # creating a ReedSolomon code; be patient sage: code [64, 32] evaluation AG code over GF(64) sage: decoder = code.decoder('K') # be patient once more sage: tau = decoder.decoding_radius() sage: tau 16 sage: channel = channels.StaticErrorRateChannel(code.ambient_space(), tau) # let's try decoding sage: message_space = decoder.message_space() sage: encoder = decoder.connected_encoder() sage: message = message_space.random_element() # a random message sage: codeword = encoder.encode(message) # codeword encoding the message sage: received_vector = channel(codeword) # codeword sent through the noisy channel sage: (received_vector  codeword).hamming_weight() 16 sage: decoder.decode_to_code(received_vector) == codeword # recovered the codeword True sage: decoder.decode_to_message(received_vector) == message # recovered the message True
Algebra
New algebraic objects
The alternating central extension of the Onsager (Lie) algebra #32142
Invariant module of a finitedimensional module under a semigroup action #31939
The twisted invariant module of a finitedimensional module under a group action #32145
The quantum Clifford algebra #32094
Bug fixes and improvements
Creating submodules of the module of matrices #31995
Class functions are now hashable #32190
float^complex now works #11323
x * ((3*i + 4)*x  5) no longer segfaults #31869
Improve computation of sign for QQbar elements #31767
Implement special class for quadratic number field elements to improve coefficient computations #31810
AdditiveAbelianGroupWrapper._discrete_log() now uses a proper blackbox group algorithm rather than brute force. #23940
Hyperbolic geometry
Bug fixed with computing the Möbius transform, midpoint, and perpendicular bisector in the hyperbolic plane. Now the computation of midpoint and perp. bisector is order independent. #29936
Configuration changes
Support for system gcc/g++/gfortran 11 added
Sage can now be built using GCC 11. #31786
This enables building Sage using the default compiler on Fedora 34, and on macOS with homebrew using the default compilers. (Previously, in Sage 9.3, specific older versions of the compilers had to be installed.)
Support for system Python 3.6 dropped
It was already deprecated in Sage 9.3. #30551
It is still possible to build the Sage distribution on systems with old Python versions, but Sage will build its own copy of Python 3.9.x in this case.
Support for optional packages on systems with gcc 4.x dropped
Sage is phasing out its support for building from source using very old compilers from the gcc 4.x series.
As of Sage 9.4, on systems such as ubuntutrusty (Ubuntu 14.04), debianjessie (8), linuxmint17, and centos7 that only provide gcc from the outdated 4.x series, it is still supported to build Sage from source with the system compilers. However, building optional and experimental packages is no longer supported, and we have removed these configurations from our CI. #31526
Users in scientific computing environments using these platforms should urge their system administrators to upgrade to a newer distribution, or at least to a newer toolchain.
For developers: ./configure prefix=SAGE_LOCAL withsagevenv=SAGE_VENV
Sage 9.4 makes it possible to configure the build to make a distinction between:
the installation tree for nonPython packages (SAGE_LOCAL, which defaults to SAGE_ROOT/local and can be set using the configure option prefix), and
the installation tree (virtual environment) for Python packages (SAGE_VENV). By default, SAGE_VENV is just the same as SAGE_LOCAL, but it can be set to an arbitrary directory using the configure option withsagevenv.
Package installation records are kept within each tree, and thus separately. This allows developers to switch between different system Python versions without having to rebuild the whole set of nonPython packages. See #29013 for details.
Package upgrades
FLINT and Arb
FLINT has been upgraded to 2.7.1 in #31069. Sage 9.4 has added support for using FLINT 2.8.x on systems that provide it in #32175. The minimum supported FLINT version is now 2.6.0 #31525. Sage developers can now make use of more FLINT features added in the 2.x development series, see Metaticket #31408: Use new features from FLINT 2.x.
Arb has been upgraded to 2.19.0, which brings various performance improvements.
NumPy and SciPy
Many upgrades were enabled by dropping support for Python 3.6.
In particular, NumPy has been upgraded to 1.20.3 in #31008. Sage users benefit from many improvements made in the NumPy 1.20 series. The minimum version of NumPy supported by the Sage library, according to build/pkgs/numpy/installrequires.txt, is still 1.19 (slightly ahead of the NEP 29 drop schedule).
SciPy has been upgraded to 1.6.3 in #31008; the minimum version supported by the Sage library, according to build/pkgs/scipy/installrequires.txt, is still 1.5. The SciPy 1.6 series has brought many improvements. Among the many highlights, the integration of the highperformance linear programming library HiGHS stands out. #32282 tracks the task of making use of it as a backend of MixedIntegerLinearProgram in Sage.
lrslib and polymake
lrslib, providing reverse search algorithms for vertex enumeration for polyhedra and equilibrium problems, has been upgraded to version 071b, which promises major speedups thanks to a new hybrid arithmetic. #27745
polymake, a powerful system for computations with convex polyhedra, simplicial complexes, matroids, graphs, and tropical hypersurfaces, has been upgraded to version 4.4 in #27745. The major upgrade from version 3.4 has brought many improvements made during the polymake 3.5, 3.6, 4.0, 4.1, 4.2, 4.3, and 4.4 development cycles. To use polymake from Sage, use sage i jupymake, which activates a more robust interface; the original pexpectbased interface is now deprecated. Sage 9.4 also contains a number of interface and packaging improvements for polymake. #26368, #31864, #31840
PARI/GP and GAP
PARI/GP, the computer algebra system designed for fast computations in number theory, has been upgraded to 2.13.1 in #30801. The upgrade from version 2.11.4 has brought many improvements.
GAP, the system for computational group theory and other discrete algebra, has been upgraded to 4.11.1. Although considered by upstream as a minor update from version 4.11.0, which was included in Sage 9.3, it provides many improvements and updates to GAP packages.
Maxima and FriCAS
The symbolics packages Maxima and FriCAS, both running on Embeddable Common Lisp (ECL), have been upgraded to 5.45.0 and 1.3.7, respectively.
Also, if ECL 21.2.1 is provided by a system package, Sage is now able to use it instead of building its own copy. #29617
New standard packages
memory_allocator is a new standard package. See #31591
Other upgrades
For developers and packagers: Refactoring, modernization, and modularization
Using type annotations (PEP 563) in the Sage library
Dropping support for Python 3.6 has allowed us to start using language and library features introduced in Python 3.7. Metaticket #29756 tracks such features by Python version.
One notable new feature of Python 3.7 is type annotations for function arguments and return values. Sage 9.4 has started to make use of this feature, in the revised form that PEP 563 provides (from __future__ import annotations). A new section in the developer's manual added in #32067 provides guidance on how to use this feature. See #32058, #32128, #32164 for examples.
New location for distribution package sources: SAGE_ROOT/pkgs
The Sage source tree contains a number of source trees of Python distribution packages. In Sage 9.4, they have been moved to a new central location. #31577
SAGE_ROOT  pkgs  sageconf  setup.py  bin/  sage_conf.py.in  sagedocbuild  setup.py  sage_docbuild > symlinks to SAGE_ROOT/sage_docbuild/  sagesws2rst  setup.py  bin/  sage_sws2rst/  sagemathstandard  setup.py  bin > symlinks to SAGE_ROOT/src/bin/  sage > symlinks to SAGE_ROOT/src/sage/  sage_setup > symlinks to SAGE_ROOT/src/sage_setup/
that is, the new directory pkgs is on the same level as
SAGE_ROOT  src
the unchanged monolithic sagelib source tree, which will continue to contain subdirectories
 bin/  doc/  sage/  sage_docbuild/ # was sage_setup/docbuild/ in Sage 9.2  sage_setup/
All files that contain Sage doctests (tested with sage t or make ptest) remain in the monolithic src/ source tree; the source trees of the distributions symlink there.
Other modularization tickets will add
SAGE_ROOT  pkgs  sagemathcore/  sagemathbrial/  sagemathgiac/  sagemathmeataxe/  sagemathtdlib/
etc.; see Metaticket #29705 for more information.
Modern Python packaging metadata for sagemathstandard
./bootstrap now generates modern Python packaging metadata (pyproject.toml and setup.cfg, as well as requirements.txt and Pipfile) for our distribution package sagemathstandard. #30913
The version information for dependencies comes from the existing files build/pkgs/*/installrequires.txt.
Using cython.parallel in sage
One can now use cython.parallel for parallel cython code, as demonstrated in #31245.
The following cython code will work (in a source file and compiled in the shell):
# distutils: extra_compile_args = OPENMP_CFLAGS # distutils: extra_link_args = OPENMP_CFLAGS from cython.parallel cimport prange, threadid def foo(): cdef int i, sum sum = 0 for i in prange(1000, num_threads=8, schedule='dynamic', nogil=True): sum += threadid() return sum
OPENMP_CFLAGS and OPENMP_CXXFLAGS will be configured nonempty on many systems, if OpenMP is detected and working. If empty, the above code will still compile fine and run on only 1 thread instead. In particular one needs to use cython.parallel functions and not call OpenMP directly, e.g. with omp_get_thread_num.
Availability of Sage 9.4 and installation help
Sage 9.4 was released on 20210822.
Sources
The Sage source code is available in the sage git repository, and the selfcontained source tarballs are available for download.
SageMath 9.4 supports most platforms that were supported by Sage 9.3. Sage 9.4 now has support for building Sage from source on macOS 11 ("Big Sur") with the default compilers from Xcode; and the default compilers from homebrew. Our CI now tests also several flavors of openSUSE Linux.
Sage 9.4 has been tested to compile from source on a wide variety of platforms, including:
Linux 64bit (x86_64)
 ubuntu{trusty⁺,xenial,bionic,focal,groovy,hirsute},
 debian{jessie⁺,stretch,buster,bullseye},
 linuxmint{17⁺,18,19,19.3,20.1},
 fedora{26,27,28,29,30,31,32,33,34},
 centos{7⁺,8},
 gentoo,
 archlinux,
 opensuse{15,15.3,tumbleweed},
 slackware14.2
Linux 32bit (i386)
 debianbuster
 ubuntubionic
 centos7⁺
 manylinux2_24
macOS
 macOS Catalina and older (macOS 10.x, with Xcode 11.x or Xcode 12.x)
 macOS Big Sur (macOS 11.x, with XCode 12.x)
 optionally, using Homebrew
Windows (Cygwin64).
(On platforms marked with ⁺, optional packages are only supported if configure withoutsystemgcc is in use.)
There are currently known issues with an installation from source on condaforge, both on Linux and macOS. This has been addressed in the Sage 9.5 development series.
Sage 9.4 does not support building on recent Linux distributions that use glibc >= 2.34 (fedora35, ubuntuimpish etc.) This has been addressed in the Sage 9.5 development series; you will need version 9.5.beta9 or later.
Installation FAQ
See README.md in the source distribution for installation instructions.
See sagerelease, sagedevel.
Availability as binaries and in distributions
The easiest way to install Sage 9.4 is through a distribution that provides it, see repology.org: sagemath.
A binary build of Sage 9.4 for macOS as a signed and notarized app is available. You can choose between two options: A 800 MB disk image with the standard Sage distribution, and a 1 GB disk image that adds many optional packages.
Binaries for Linux platforms are available.
If you get the error /usr/bin/env: 'python': No such file or directory. Error running the script 'relocateonce.py'.: Make sure that you have python installed in your system. On some recent Linux distributions, there is a python3 binary but no python binary. In this case, edit the first line of relocateonce.py to change python to python3; or install a package that provides the symlink /usr/bin/python>python3 (for Ubuntu 20.04, this is the package pythonispython3).
If Sage crashes when plotting or on other numerical operations, the binary distribution is not compatible with your CPU type. This is a known bug in the binary distribution that also affects the Sage 9.3 release; see #32424. Install from source instead.
Note also that the binary packages do not support installing optional Sage packages. If you need any of these packages, install Sage from source instead, see above.
Sage 9.4 is available on the CoCalc.com online workspace; however, the CoCalc docker image is still using Sage 9.3.
Alternative installation methods using pip
Since Sage 9.3, installation methods using pip are available.
$ python3 m pip install sage_conf
This will download the distribution package (sdist) sage_conf from PyPI, which will build the nonPython components of the Sage distribution in a subdirectory of $HOME/.sage.
After installation of sage_conf, a wheelhouse containing wheels of various Python packages is available; type ls $(sageconfig SAGE_SPKG_WHEELS) to list them and python3 m pip install $(sageconfig SAGE_SPKG_WHEELS)/*.whl to install them.
After this, you can install the Sage library, using any of these options:
using python3 m pip install sagemathstandard, which downloads the Sage library from PyPI
or, after obtaining the Sage sources from git, (make configure && cd src && python3 m pip install v editable .)
pipinstallable subset distributions
Two new, experimental distribution packages are available on PyPI: #29865