def _init_from_Vrepresentation(self, vertices, rays, lines, minimize=True, verbose=False):
r"""
Construct polyhedron from V-representation data.
INPUT:
- ``vertices`` -- list of point; each point can be specified
as any iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``rays`` -- list of rays; each ray can be specified as any
iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``lines`` -- list of lines; each line can be specified as
any iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``verbose`` -- boolean (default: ``False``); whether to print
verbose output for debugging purposes
EXAMPLES::
sage: p = Polyhedron(backend='polymake') # optional - polymake
sage: from sage.geometry.polyhedron.backend_polymake import Polyhedron_polymake # optional - polymake
sage: Polyhedron_polymake._init_from_Vrepresentation(p, [], [], []) # optional - polymake
"""
from sage.interfaces.polymake import polymake
polymake_field = polymake(self.base_ring().fraction_field())
p = polymake.new_object("Polytope<{}>".format(polymake_field),
CONE_AMBIENT_DIM=1+self.parent().ambient_dim(),
POINTS= [ [1] + v for v in vertices ] \
+ [ [0] + r for r in rays ],
INPUT_LINEALITY=[ [0] + l for l in lines ])
self._init_from_polymake_polytope(p)
def _init_from_Hrepresentation(self,
ieqs,
eqns,
minimize=True,
verbose=False):
r"""
Construct polyhedron from H-representation data.
INPUT:
- ``ieqs`` -- list of inequalities; each line can be specified
as any iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``eqns`` -- list of equalities; each line can be specified
as any iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``minimize`` -- boolean (default: ``True``); ignored
- ``verbose`` -- boolean (default: ``False``); whether to print
verbose output for debugging purposes
EXAMPLES::
sage: p = Polyhedron(backend='polymake') # optional - polymake
sage: from sage.geometry.polyhedron.backend_polymake import Polyhedron_polymake # optional - polymake
sage: Polyhedron_polymake._init_from_Hrepresentation(p, [], []) # optional - polymake
"""
from sage.interfaces.polymake import polymake
data = self._polymake_Hrepresentation_data(ieqs, eqns)
polymake_field = polymake(self.base_ring().fraction_field())
p = polymake.new_object("Polytope<{}>".format(polymake_field), **data)
self._init_from_polymake_polytope(p)
def _init_from_Hrepresentation(self,
ieqs,
eqns,
minimize=True,
verbose=False):
r"""
Construct polyhedron from H-representation data.
INPUT:
- ``ieqs`` -- list of inequalities; each line can be specified
as any iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``eqns`` -- list of equalities; each line can be specified
as any iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``minimize`` -- boolean (default: ``True``); ignored
- ``verbose`` -- boolean (default: ``False``); whether to print
verbose output for debugging purposes
EXAMPLES::
sage: p = Polyhedron(backend='polymake') # optional - polymake
sage: from sage.geometry.polyhedron.backend_polymake import Polyhedron_polymake # optional - polymake
sage: Polyhedron_polymake._init_from_Hrepresentation(p, [], []) # optional - polymake
"""
from sage.interfaces.polymake import polymake
if ieqs is None: ieqs = []
if eqns is None: eqns = []
# Polymake 3.0r2 and 3.1 crash with a segfault for a test case
# using QuadraticExtension, when some all-zero inequalities are input.
# https://forum.polymake.org/viewtopic.php?f=8&t=547
# Filter them out.
ieqs = [v for v in ieqs if not all(self._is_zero(x) for x in v)]
# We do a similar filtering for equations.
# Since Polymake 3.2, we can not give all zero vectors in equations
eqns = [v for v in eqns if not all(self._is_zero(x) for x in v)]
if not ieqs:
# Put in one trivial (all-zero) inequality. This is so that
# the ambient dimension is set correctly.
# Since Polymake 3.2, the constant should not be zero.
ieqs.append([1] + [0] * self.ambient_dim())
polymake_field = polymake(self.base_ring().fraction_field())
p = polymake.new_object("Polytope<{}>".format(polymake_field),
EQUATIONS=eqns,
INEQUALITIES=ieqs)
self._init_from_polymake_polytope(p)
def _init_from_Hrepresentation(self, ieqs, eqns, minimize=True, verbose=False):
r"""
Construct polyhedron from H-representation data.
INPUT:
- ``ieqs`` -- list of inequalities; each line can be specified
as any iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``eqns`` -- list of equalities; each line can be specified
as any iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``minimize`` -- boolean (default: ``True``); ignored
- ``verbose`` -- boolean (default: ``False``); whether to print
verbose output for debugging purposes
EXAMPLES::
sage: p = Polyhedron(backend='polymake') # optional - polymake
sage: from sage.geometry.polyhedron.backend_polymake import Polyhedron_polymake # optional - polymake
sage: Polyhedron_polymake._init_from_Hrepresentation(p, [], []) # optional - polymake
"""
from sage.interfaces.polymake import polymake
if ieqs is None: ieqs = []
if eqns is None: eqns = []
# Polymake 3.0r2 and 3.1 crash with a segfault for a test case
# using QuadraticExtension, when some all-zero inequalities are input.
# https://forum.polymake.org/viewtopic.php?f=8&t=547
# Filter them out.
ieqs = [ v for v in ieqs if not all(self._is_zero(x) for x in v) ]
if not ieqs:
# Put in one trivial (all-zero) inequality. This is so that
# the ambient dimension is set correctly.
ieqs.append([0] + [0]*self.ambient_dim())
polymake_field = polymake(self.base_ring().fraction_field())
p = polymake.new_object("Polytope<{}>".format(polymake_field),
EQUATIONS=eqns,
INEQUALITIES=ieqs)
self._init_from_polymake_polytope(p)
def _init_from_Vrepresentation(self,
vertices,
rays,
lines,
minimize=True,
verbose=False):
r"""
Construct polyhedron from V-representation data.
INPUT:
- ``vertices`` -- list of point; each point can be specified
as any iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``rays`` -- list of rays; each ray can be specified as any
iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``lines`` -- list of lines; each line can be specified as
any iterable container of
:meth:`~sage.geometry.polyhedron.base.base_ring` elements
- ``verbose`` -- boolean (default: ``False``); whether to print
verbose output for debugging purposes
EXAMPLES::
sage: p = Polyhedron(backend='polymake') # optional - polymake
sage: from sage.geometry.polyhedron.backend_polymake import Polyhedron_polymake # optional - polymake
sage: Polyhedron_polymake._init_from_Vrepresentation(p, [], [], []) # optional - polymake
"""
from sage.interfaces.polymake import polymake
polymake_field = polymake(self.base_ring().fraction_field())
p = polymake.new_object("Polytope<{}>".format(polymake_field),
CONE_AMBIENT_DIM=1+self.parent().ambient_dim(),
POINTS= [ [1] + v for v in vertices ] \
+ [ [0] + r for r in rays ],
INPUT_LINEALITY=[ [0] + l for l in lines ])
self._init_from_polymake_polytope(p)
def _polymake_polytope_from_Vrepresentation_and_Hrepresentation(
self, Vrep, Hrep):
if not any(Vrep):
# The empty polyhedron.
return
from sage.interfaces.polymake import polymake
data = self._polymake_Vrepresentation_data(*Vrep, minimal=True)
if any(Vrep[1:]):
from sage.matrix.constructor import Matrix
polymake_rays = [r for r in data['VERTICES'] if r[0] == 0]
if Matrix(data['VERTICES']).rank(
) == Matrix(polymake_rays).rank() + 1:
# The recession cone is full-dimensional.
# In this case the homogenized inequalities
# do not ensure nonnegativy in the last coordinate.
# In the homogeneous cone the far face is a facet.
Hrep[0] += [[1] + [0] * self.ambient_dim()]
data.update(self._polymake_Hrepresentation_data(*Hrep, minimal=True))
polymake_field = polymake(self.base_ring().fraction_field())
return polymake.new_object("Polytope<{}>".format(polymake_field),
**data)
def Polyhedra(ambient_space_or_base_ring=None,
ambient_dim=None,
backend=None,
*,
ambient_space=None,
base_ring=None):
r"""
Construct a suitable parent class for polyhedra
INPUT:
- ``base_ring`` -- A ring. Currently there are backends for `\ZZ`,
`\QQ`, and `\RDF`.
- ``ambient_dim`` -- integer. The ambient space dimension.
- ``ambient_space`` -- A free module.
- ``backend`` -- string. The name of the backend for computations. There are
several backends implemented:
* ``backend="ppl"`` uses the Parma Polyhedra Library
* ``backend="cdd"`` uses CDD
* ``backend="normaliz"`` uses normaliz
* ``backend="polymake"`` uses polymake
* ``backend="field"`` a generic Sage implementation
OUTPUT:
A parent class for polyhedra over the given base ring if the
backend supports it. If not, the parent base ring can be larger
(for example, `\QQ` instead of `\ZZ`). If there is no
implementation at all, a ``ValueError`` is raised.
EXAMPLES::
sage: from sage.geometry.polyhedron.parent import Polyhedra
sage: Polyhedra(AA, 3)
Polyhedra in AA^3
sage: Polyhedra(ZZ, 3)
Polyhedra in ZZ^3
sage: type(_)
<class 'sage.geometry.polyhedron.parent.Polyhedra_ZZ_ppl_with_category'>
sage: Polyhedra(QQ, 3, backend='cdd')
Polyhedra in QQ^3
sage: type(_)
<class 'sage.geometry.polyhedron.parent.Polyhedra_QQ_cdd_with_category'>
CDD does not support integer polytopes directly::
sage: Polyhedra(ZZ, 3, backend='cdd')
Polyhedra in QQ^3
Using a more general form of the constructor::
sage: V = VectorSpace(QQ, 3)
sage: Polyhedra(V) is Polyhedra(QQ, 3)
True
sage: Polyhedra(V, backend='field') is Polyhedra(QQ, 3, 'field')
True
sage: Polyhedra(backend='field', ambient_space=V) is Polyhedra(QQ, 3, 'field')
True
sage: M = FreeModule(ZZ, 2)
sage: Polyhedra(M, backend='ppl') is Polyhedra(ZZ, 2, 'ppl')
True
TESTS::
sage: Polyhedra(RR, 3, backend='field')
Traceback (most recent call last):
...
ValueError: the 'field' backend for polyhedron cannot be used with non-exact fields
sage: Polyhedra(RR, 3)
Traceback (most recent call last):
...
ValueError: no default backend for computations with Real Field with 53 bits of precision
sage: Polyhedra(QQ[I], 2)
Traceback (most recent call last):
...
ValueError: invalid base ring: Number Field in I with defining polynomial x^2 + 1 with I = 1*I cannot be coerced to a real field
sage: Polyhedra(AA, 3, backend='polymake') # optional - polymake
Traceback (most recent call last):
...
ValueError: the 'polymake' backend for polyhedron cannot be used with Algebraic Real Field
sage: Polyhedra(QQ, 2, backend='normaliz') # optional - pynormaliz
Polyhedra in QQ^2
sage: Polyhedra(SR, 2, backend='normaliz') # optional - pynormaliz # optional - sage.symbolic
Polyhedra in (Symbolic Ring)^2
sage: SCR = SR.subring(no_variables=True) # optional - sage.symbolic
sage: Polyhedra(SCR, 2, backend='normaliz') # optional - pynormaliz # optional - sage.symbolic
Polyhedra in (Symbolic Constants Subring)^2
"""
if ambient_space_or_base_ring is not None:
if ambient_space_or_base_ring in Rings():
base_ring = ambient_space_or_base_ring
else:
ambient_space = ambient_space_or_base_ring
if ambient_space is not None:
if ambient_space not in Modules:
# There is no category of free modules, unfortunately
# (see https://trac.sagemath.org/ticket/30164)...
raise ValueError('ambient_space must be a free module')
if base_ring is None:
base_ring = ambient_space.base_ring()
if ambient_dim is None:
try:
ambient_dim = ambient_space.rank()
except AttributeError:
# ... so we test whether it is free using the existence of
# a rank method
raise ValueError('ambient_space must be a free module')
if ambient_space is not FreeModule(base_ring, ambient_dim):
raise NotImplementedError(
'ambient_space must be a standard free module')
if backend is None:
if base_ring is ZZ or base_ring is QQ:
backend = 'ppl'
elif base_ring is RDF:
backend = 'cdd'
elif base_ring.is_exact():
# TODO: find a more robust way of checking that the coefficients are indeed
# real numbers
if not RDF.has_coerce_map_from(base_ring):
raise ValueError(
"invalid base ring: {} cannot be coerced to a real field".
format(base_ring))
backend = 'field'
else:
raise ValueError(
"no default backend for computations with {}".format(
base_ring))
try:
from sage.symbolic.ring import SR
except ImportError:
SR = None
if backend == 'ppl' and base_ring is QQ:
return Polyhedra_QQ_ppl(base_ring, ambient_dim, backend)
elif backend == 'ppl' and base_ring is ZZ:
return Polyhedra_ZZ_ppl(base_ring, ambient_dim, backend)
elif backend == 'normaliz' and base_ring is QQ:
return Polyhedra_QQ_normaliz(base_ring, ambient_dim, backend)
elif backend == 'normaliz' and base_ring is ZZ:
return Polyhedra_ZZ_normaliz(base_ring, ambient_dim, backend)
elif backend == 'normaliz' and (isinstance(
base_ring, sage.rings.abc.SymbolicRing) or base_ring.is_exact()):
return Polyhedra_normaliz(base_ring, ambient_dim, backend)
elif backend == 'cdd' and base_ring in (ZZ, QQ):
return Polyhedra_QQ_cdd(QQ, ambient_dim, backend)
elif backend == 'cdd' and base_ring is RDF:
return Polyhedra_RDF_cdd(RDF, ambient_dim, backend)
elif backend == 'polymake':
base_field = base_ring.fraction_field()
try:
from sage.interfaces.polymake import polymake
polymake_base_field = polymake(base_field)
except TypeError:
raise ValueError(
f"the 'polymake' backend for polyhedron cannot be used with {base_field}"
)
return Polyhedra_polymake(base_field, ambient_dim, backend)
elif backend == 'field':
if not base_ring.is_exact():
raise ValueError(
"the 'field' backend for polyhedron cannot be used with non-exact fields"
)
return Polyhedra_field(base_ring.fraction_field(), ambient_dim,
backend)
else:
raise ValueError('No such backend (=' + str(backend) +
') implemented for given basering (=' +
str(base_ring) + ').')
