示例#1
0
def FormsRing(analytic_type, group=3, base_ring=ZZ, red_hom=False):
    r"""
    Return the FormsRing with the given ``analytic_type``, ``group``
    ``base_ring`` and variable ``red_hom``.

    INPUT:

    - ``analytic_type``  -- An element of ``AnalyticType()`` describing
                            the analytic type of the space.

    - ``group``          -- The index of the (Hecke triangle) group of the space
                            (default: 3`).

    - ``base_ring``      -- The base ring of the space
                            (default: ``ZZ``).

    - ``red_hom``        -- The (boolean= variable ``red_hom`` of the space
                            (default: ``False``).

    For the variables ``group``, ``base_ring``, ``red_hom``
    the same arguments as for the class ``FormsRing_abstract`` can be used.
    The variables will then be put in canonical form.

    OUTPUT:

    The FormsRing with the given properties.

    EXAMPLES::

        sage: from sage.modular.modform_hecketriangle.constructor import FormsRing
        sage: FormsRing("cusp", group=5, base_ring=CC)
        CuspFormsRing(n=5) over Complex Field with 53 bits of precision

        sage: FormsRing("holo")
        ModularFormsRing(n=3) over Integer Ring

        sage: FormsRing("weak", group=6, base_ring=ZZ, red_hom=True)
        WeakModularFormsRing(n=6) over Integer Ring

        sage: FormsRing("mero", group=7, base_ring=ZZ)
        MeromorphicModularFormsRing(n=7) over Integer Ring

        sage: FormsRing(["quasi", "cusp"], group=5, base_ring=CC)
        QuasiCuspFormsRing(n=5) over Complex Field with 53 bits of precision

        sage: FormsRing(["quasi", "holo"])
        QuasiModularFormsRing(n=3) over Integer Ring

        sage: FormsRing(["quasi", "weak"], group=6, base_ring=ZZ, red_hom=True)
        QuasiWeakModularFormsRing(n=6) over Integer Ring

        sage: FormsRing(["quasi", "mero"], group=7, base_ring=ZZ, red_hom=True)
        QuasiMeromorphicModularFormsRing(n=7) over Integer Ring

        sage: FormsRing(["quasi", "cusp"], group=infinity)
        QuasiCuspFormsRing(n=+Infinity) over Integer Ring
    """

    from graded_ring import canonical_parameters
    (group, base_ring, red_hom,
     n) = canonical_parameters(group, base_ring, red_hom)

    from analytic_type import AnalyticType
    AT = AnalyticType()
    analytic_type = AT(analytic_type)

    if analytic_type <= AT("mero"):
        if analytic_type <= AT("weak"):
            if analytic_type <= AT("holo"):
                if analytic_type <= AT("cusp"):
                    if analytic_type <= AT([]):
                        raise ValueError(
                            "Analytic type Zero is not valid for forms rings.")
                    else:
                        from graded_ring import CuspFormsRing
                        return CuspFormsRing(group=group,
                                             base_ring=base_ring,
                                             red_hom=red_hom)
                else:
                    from graded_ring import ModularFormsRing
                    return ModularFormsRing(group=group,
                                            base_ring=base_ring,
                                            red_hom=red_hom)
            else:
                from graded_ring import WeakModularFormsRing
                return WeakModularFormsRing(group=group,
                                            base_ring=base_ring,
                                            red_hom=red_hom)
        else:
            from graded_ring import MeromorphicModularFormsRing
            return MeromorphicModularFormsRing(group=group,
                                               base_ring=base_ring,
                                               red_hom=red_hom)
    elif analytic_type <= AT(["mero", "quasi"]):
        if analytic_type <= AT(["weak", "quasi"]):
            if analytic_type <= AT(["holo", "quasi"]):
                if analytic_type <= AT(["cusp", "quasi"]):
                    if analytic_type <= AT(["quasi"]):
                        raise ValueError(
                            "Analytic type Zero is not valid for forms rings.")
                    else:
                        from graded_ring import QuasiCuspFormsRing
                        return QuasiCuspFormsRing(group=group,
                                                  base_ring=base_ring,
                                                  red_hom=red_hom)
                else:
                    from graded_ring import QuasiModularFormsRing
                    return QuasiModularFormsRing(group=group,
                                                 base_ring=base_ring,
                                                 red_hom=red_hom)
            else:
                from graded_ring import QuasiWeakModularFormsRing
                return QuasiWeakModularFormsRing(group=group,
                                                 base_ring=base_ring,
                                                 red_hom=red_hom)
        else:
            from graded_ring import QuasiMeromorphicModularFormsRing
            return QuasiMeromorphicModularFormsRing(group=group,
                                                    base_ring=base_ring,
                                                    red_hom=red_hom)
    else:
        raise NotImplementedError("Analytic type not implemented.")
示例#2
0
def FormsSpace(analytic_type, group=3, base_ring=ZZ, k=QQ(0), ep=None):
    r"""
    Return the FormsSpace with the given ``analytic_type``, ``group``
    ``base_ring`` and degree (``k``, ``ep``).

    INPUT:

    - ``analytic_type``   -- An element of ``AnalyticType()`` describing
                             the analytic type of the space.

    - ``group``           -- The index of the (Hecke triangle) group of the
                             space (default: `3`).

    - ``base_ring``       -- The base ring of the space
                             (default: ``ZZ``).

    - ``k``               -- The weight of the space, a rational number
                             (default: ``0``).

    - ``ep``              -- The multiplier of the space, `1`, `-1`
                             or ``None`` (in case ``ep`` should be
                             determined from ``k``). Default: ``None``.

    For the variables ``group``, ``base_ring``, ``k``, ``ep``
    the same arguments as for the class ``FormsSpace_abstract`` can be used.
    The variables will then be put in canonical form.
    In particular the multiplier ``ep`` is calculated
    as usual from ``k`` if ``ep == None``.

    OUTPUT:

    The FormsSpace with the given properties.

    EXAMPLES::

        sage: from sage.modular.modform_hecketriangle.constructor import FormsSpace
        sage: FormsSpace([])
        ZeroForms(n=3, k=0, ep=1) over Integer Ring
        sage: FormsSpace(["quasi"]) # not implemented

        sage: FormsSpace("cusp", group=5, base_ring=CC, k=12, ep=1)
        CuspForms(n=5, k=12, ep=1) over Complex Field with 53 bits of precision

        sage: FormsSpace("holo")
        ModularForms(n=3, k=0, ep=1) over Integer Ring

        sage: FormsSpace("weak", group=6, base_ring=ZZ, k=0, ep=-1)
        WeakModularForms(n=6, k=0, ep=-1) over Integer Ring

        sage: FormsSpace("mero", group=7, base_ring=ZZ, k=2, ep=-1)
        MeromorphicModularForms(n=7, k=2, ep=-1) over Integer Ring

        sage: FormsSpace(["quasi", "cusp"], group=5, base_ring=CC, k=12, ep=1)
        QuasiCuspForms(n=5, k=12, ep=1) over Complex Field with 53 bits of precision

        sage: FormsSpace(["quasi", "holo"])
        QuasiModularForms(n=3, k=0, ep=1) over Integer Ring

        sage: FormsSpace(["quasi", "weak"], group=6, base_ring=ZZ, k=0, ep=-1)
        QuasiWeakModularForms(n=6, k=0, ep=-1) over Integer Ring

        sage: FormsSpace(["quasi", "mero"], group=7, base_ring=ZZ, k=2, ep=-1)
        QuasiMeromorphicModularForms(n=7, k=2, ep=-1) over Integer Ring

        sage: FormsSpace(["quasi", "cusp"], group=infinity, base_ring=ZZ, k=2, ep=-1)
        QuasiCuspForms(n=+Infinity, k=2, ep=-1) over Integer Ring
    """

    from space import canonical_parameters
    (group, base_ring, k, ep,
     n) = canonical_parameters(group, base_ring, k, ep)

    from analytic_type import AnalyticType
    AT = AnalyticType()
    analytic_type = AT(analytic_type)

    if analytic_type <= AT("mero"):
        if analytic_type <= AT("weak"):
            if analytic_type <= AT("holo"):
                if analytic_type <= AT("cusp"):
                    if analytic_type <= AT([]):
                        from space import ZeroForm
                        return ZeroForm(group=group,
                                        base_ring=base_ring,
                                        k=k,
                                        ep=ep)
                    else:
                        from space import CuspForms
                        return CuspForms(group=group,
                                         base_ring=base_ring,
                                         k=k,
                                         ep=ep)
                else:
                    from space import ModularForms
                    return ModularForms(group=group,
                                        base_ring=base_ring,
                                        k=k,
                                        ep=ep)
            else:
                from space import WeakModularForms
                return WeakModularForms(group=group,
                                        base_ring=base_ring,
                                        k=k,
                                        ep=ep)
        else:
            from space import MeromorphicModularForms
            return MeromorphicModularForms(group=group,
                                           base_ring=base_ring,
                                           k=k,
                                           ep=ep)
    elif analytic_type <= AT(["mero", "quasi"]):
        if analytic_type <= AT(["weak", "quasi"]):
            if analytic_type <= AT(["holo", "quasi"]):
                if analytic_type <= AT(["cusp", "quasi"]):
                    if analytic_type <= AT(["quasi"]):
                        raise ValueError(
                            "There should be only non-quasi ZeroForms. That could be changed but then this exception should be removed."
                        )
                        from space import ZeroForm
                        return ZeroForm(group=group,
                                        base_ring=base_ring,
                                        k=k,
                                        ep=ep)
                    else:
                        from space import QuasiCuspForms
                        return QuasiCuspForms(group=group,
                                              base_ring=base_ring,
                                              k=k,
                                              ep=ep)
                else:
                    from space import QuasiModularForms
                    return QuasiModularForms(group=group,
                                             base_ring=base_ring,
                                             k=k,
                                             ep=ep)
            else:
                from space import QuasiWeakModularForms
                return QuasiWeakModularForms(group=group,
                                             base_ring=base_ring,
                                             k=k,
                                             ep=ep)
        else:
            from space import QuasiMeromorphicModularForms
            return QuasiMeromorphicModularForms(group=group,
                                                base_ring=base_ring,
                                                k=k,
                                                ep=ep)
    else:
        raise NotImplementedError("Analytic type not implemented.")
示例#3
0
class FormsRingFunctor(ConstructionFunctor):
    r"""
    Construction functor for forms rings.

    NOTE:

    When the base ring is not a ``BaseFacade`` the functor is first
    merged with the ConstantFormsSpaceFunctor.  This case occurs in
    the pushout constructions.  (when trying to find a common parent
    between a forms ring and a ring which is not a ``BaseFacade``).
    """

    from analytic_type import AnalyticType
    AT = AnalyticType()

    rank = 10

    def __init__(self, analytic_type, group, red_hom):
        r"""
        Construction functor for the forms ring
        with the given ``analytic_type``, ``group``
        and variable ``red_hom``

        See :meth:`__call__` for a description of the functor.

        INPUT:

        - ``analytic_type``  -- An element of ``AnalyticType()``.

        - ``group``          -- The index of a Hecke Triangle group.

        - ``red_hom``        -- A boolean variable for the parameter ``red_hom``
                                (also see ``FormsRing_abstract``).

        OUTPUT:

        The construction functor for the corresponding forms ring.

        EXAMPLES::

            sage: from sage.modular.modform_hecketriangle.functors import FormsRingFunctor
            sage: FormsRingFunctor(["quasi", "mero"], group=6, red_hom=False)
            QuasiMeromorphicModularFormsRingFunctor(n=6)
            sage: FormsRingFunctor(["quasi", "mero"], group=6, red_hom=True)
            QuasiMeromorphicModularFormsRingFunctor(n=6, red_hom=True)
        """

        Functor.__init__(self, Rings(), Rings())
        from graded_ring import canonical_parameters
        (self._group, R, red_hom, n) = canonical_parameters(group, ZZ, red_hom)
        self._red_hom = bool(red_hom)
        self._analytic_type = self.AT(analytic_type)

    def __call__(self, R):
        r"""
        If ``R`` is a ``BaseFacade(S)`` then return the corresponding
        forms ring with base ring ``_get_base_ring(S)``.

        If not then we first merge the functor with the ConstantFormsSpaceFunctor.

        EXAMPLES::

            sage: from sage.modular.modform_hecketriangle.functors import (FormsRingFunctor, BaseFacade)
            sage: F = FormsRingFunctor(["quasi", "mero"], group=6, red_hom=False)
            sage: F(BaseFacade(ZZ))
            QuasiMeromorphicModularFormsRing(n=6) over Integer Ring
            sage: F(BaseFacade(CC))
            QuasiMeromorphicModularFormsRing(n=6) over Complex Field with 53 bits of precision
            sage: F(CC)
            QuasiMeromorphicModularFormsRing(n=6) over Complex Field with 53 bits of precision
            sage: F(CC).has_reduce_hom()
            False
        """

        if (isinstance(R, BaseFacade)):
            R = _get_base_ring(R._ring)
            return FormsRing(self._analytic_type, self._group, R,
                             self._red_hom)
        else:
            R = BaseFacade(_get_base_ring(R))
            merged_functor = self.merge(ConstantFormsSpaceFunctor(self._group))
            return merged_functor(R)

    def __str__(self):
        r"""
        Return the string representation of ``self``.

        EXAMPLES::

            sage: from sage.modular.modform_hecketriangle.functors import FormsRingFunctor
            sage: str(FormsRingFunctor(["quasi", "mero"], group=6, red_hom=True))
            'QuasiMeromorphicModularFormsRingFunctor(n=6, red_hom=True)'
            sage: FormsRingFunctor(["quasi", "mero"], group=6, red_hom=False)
            QuasiMeromorphicModularFormsRingFunctor(n=6)
        """

        if (self._red_hom):
            red_arg = ", red_hom=True"
        else:
            red_arg = ""
        return "{}FormsRingFunctor(n={}{})".format(
            self._analytic_type.analytic_space_name(), self._group.n(),
            red_arg)

    def merge(self, other):
        r"""
        Return the merged functor of ``self`` and ``other``.

        It is only possible to merge instances of ``FormsSpaceFunctor``
        and ``FormsRingFunctor``. Also only if they share the same group.
        An ``FormsSubSpaceFunctors`` is replaced by its ambient space functor.

        The analytic type of the merged functor is the extension
        of the two analytic types of the functors.
        The ``red_hom`` parameter of the merged functor
        is the logical ``and`` of the two corresponding ``red_hom``
        parameters (where a forms space is assumed to have it
        set to ``True``).

        Two ``FormsSpaceFunctor`` with different (k,ep) are merged to a
        corresponding ``FormsRingFunctor``. Otherwise the corresponding
        (extended) ``FormsSpaceFunctor`` is returned.

        A ``FormsSpaceFunctor`` and ``FormsRingFunctor``
        are merged to a corresponding (extended) ``FormsRingFunctor``.

        Two ``FormsRingFunctors`` are merged to the corresponding
        (extended) ``FormsRingFunctor``.


        EXAMPLES::

            sage: from sage.modular.modform_hecketriangle.functors import (FormsSpaceFunctor, FormsRingFunctor)
            sage: functor1 = FormsRingFunctor("mero", group=6, red_hom=True)
            sage: functor2 = FormsRingFunctor(["quasi", "cusp"], group=6, red_hom=False)
            sage: functor3 = FormsSpaceFunctor("weak", group=6, k=0, ep=1)
            sage: functor4 = FormsRingFunctor("mero", group=5, red_hom=True)

            sage: functor1.merge(functor1) is functor1
            True
            sage: functor1.merge(functor4) is None
            True
            sage: functor1.merge(functor2)
            QuasiMeromorphicModularFormsRingFunctor(n=6)
            sage: functor1.merge(functor3)
            MeromorphicModularFormsRingFunctor(n=6, red_hom=True)
        """

        if (self == other):
            return self

        if isinstance(other, FormsSubSpaceFunctor):
            other = other._ambient_space_functor

        if isinstance(other, FormsSpaceFunctor):
            if not (self._group == other._group):
                return None
            red_hom = self._red_hom
            analytic_type = self._analytic_type + other._analytic_type
            return FormsRingFunctor(analytic_type, self._group, red_hom)
        elif isinstance(other, FormsRingFunctor):
            if not (self._group == other._group):
                return None
            red_hom = self._red_hom & other._red_hom
            analytic_type = self._analytic_type + other._analytic_type
            return FormsRingFunctor(analytic_type, self._group, red_hom)

    def __eq__(self, other):
        r"""
        Compare ``self`` and ``other``.

        EXAMPLES::

            sage: from sage.modular.modform_hecketriangle.functors import FormsRingFunctor
            sage: functor1 = FormsRingFunctor("holo", group=4, red_hom=True)
            sage: functor2 = FormsRingFunctor("holo", group=4, red_hom=False)
            sage: functor1 == functor2
            False
        """

        if    ( type(self)          == type(other)\
            and self._group         == other._group\
            and self._analytic_type == other._analytic_type\
            and self._red_hom       == other._red_hom ):
            return True
        else:
            return False
示例#4
0
def rational_type(f, n=ZZ(3), base_ring=ZZ):
    r"""
    Return the basic analytic properties that can be determined
    directly from the specified rational function ``f``
    which is interpreted as a representation of an
    element of a FormsRing for the Hecke Triangle group
    with parameter ``n`` and the specified ``base_ring``.

    In particular the following degree of the generators is assumed:

    `deg(1) := (0, 1)`
    `deg(x) := (4/(n-2), 1)`
    `deg(y) := (2n/(n-2), -1)`
    `deg(z) := (2, -1)`

    The meaning of homogeneous elements changes accordingly.

    INPUT:

    - ``f``              -- A rational function in ``x,y,z,d`` over ``base_ring``.

    - ``n``              -- An integer greater or equal to `3` corresponding
                            to the ``HeckeTriangleGroup`` with that parameter
                            (default: `3`).

    - ``base_ring``      -- The base ring of the corresponding forms ring, resp.
                            polynomial ring (default: ``ZZ``).

    OUTPUT:

    A tuple ``(elem, h**o, k, ep, analytic_type)`` describing the basic
    analytic properties of `f` (with the interpretation indicated above).

    - ``elem``           -- ``True`` if `f` has a homogeneous denominator.

    - ``h**o``           -- ``True`` if `f` also has a homogeneous numerator.

    - ``k``              -- ``None`` if `f` is not homogeneneous, otherwise
                            the weight of `f` (which is the first component
                            of its degree).

    - ``ep``             -- ``None`` if `f` is not homogeneous, otherwise
                            the multiplier of `f` (which is the second component
                            of its degree)

    - ``analytic_type``  -- The ``AnalyticType`` of `f`.

    For the zero function the degree `(0, 1)` is choosen.

    This function is (heavily) used to determine the type of elements
    and to check if the element really is contained in its parent.


    EXAMPLES::

        sage: from sage.modular.modform_hecketriangle.constructor import rational_type
        sage: (x,y,z,d) = var("x,y,z,d")

        sage: rational_type(0, n=4)
        (True, True, 0, 1, zero)

        sage: rational_type(1, n=12)
        (True, True, 0, 1, modular)

        sage: rational_type(x^3 - y^2)
        (True, True, 12, 1, cuspidal)

        sage: rational_type(x * z, n=7)
        (True, True, 14/5, -1, quasi modular)

        sage: rational_type(1/(x^3 - y^2) + z/d)
        (True, False, None, None, quasi weakly holomorphic modular)

        sage: rational_type(x^3/(x^3 - y^2))
        (True, True, 0, 1, weakly holomorphic modular)

        sage: rational_type(1/(x + z))
        (False, False, None, None, None)

        sage: rational_type(1/x + 1/z)
        (True, False, None, None, quasi meromorphic modular)

        sage: rational_type(d/x, n=10)
        (True, True, -1/2, 1, meromorphic modular)

        sage: rational_type(1.1 * z * (x^8-y^2), n=8, base_ring=CC)
        (True, True, 22/3, -1, quasi cuspidal)

        sage: rational_type(x-y^2, n=infinity)
        (True, True, 4, 1, modular)

        sage: rational_type(x*(x-y^2), n=infinity)
        (True, True, 8, 1, cuspidal)

        sage: rational_type(1/x, n=infinity)
        (True, True, -4, 1, weakly holomorphic modular)
    """

    from analytic_type import AnalyticType
    AT = AnalyticType()

    # Determine whether f is zero
    if (f == 0):
        #       elem, h**o, k,     ep,    analytic_type
        return (True, True, QQ(0), ZZ(1), AT([]))

    analytic_type = AT(["quasi", "mero"])

    R = PolynomialRing(base_ring, 'x,y,z,d')
    F = FractionField(R)
    (x, y, z, d) = R.gens()
    R2 = PolynomialRing(PolynomialRing(base_ring, 'd'), 'x,y,z')
    dhom = R.hom(R2.gens() + (R2.base().gen(), ), R2)

    f = F(f)

    num = R(f.numerator())
    denom = R(f.denominator())
    ep_num = set([
        ZZ(1) - 2 * ((sum([g.exponents()[0][m] for m in [1, 2]])) % 2)
        for g in dhom(num).monomials()
    ])
    ep_denom = set([
        ZZ(1) - 2 * ((sum([g.exponents()[0][m] for m in [1, 2]])) % 2)
        for g in dhom(denom).monomials()
    ])

    if (n == infinity):
        hom_num = R(num.subs(x=x**4, y=y**2, z=z**2))
        hom_denom = R(denom.subs(x=x**4, y=y**2, z=z**2))
    else:
        n = ZZ(n)
        hom_num = R(num.subs(x=x**4, y=y**(2 * n), z=z**(2 * (n - 2))))
        hom_denom = R(denom.subs(x=x**4, y=y**(2 * n), z=z**(2 * (n - 2))))

    # Determine whether the denominator of f is homogeneous
    if (len(ep_denom) == 1 and dhom(hom_denom).is_homogeneous()):
        elem = True
    else:
        #       elem,  h**o,  k,    ep,   analytic_type
        return (False, False, None, None, None)

    # Determine whether f is homogeneous
    if (len(ep_num) == 1 and dhom(hom_num).is_homogeneous()):
        h**o = True
        if (n == infinity):
            weight = (dhom(hom_num).degree() - dhom(hom_denom).degree())
        else:
            weight = (dhom(hom_num).degree() - dhom(hom_denom).degree()) / (n -
                                                                            2)
        ep = ep_num.pop() / ep_denom.pop()
    # TODO: decompose f (resp. its degrees) into homogeneous parts
    else:
        h**o = False
        weight = None
        ep = None

    # Note that we intentially leave out the d-factor!
    if (n == infinity):
        finf_pol = (x - y**2)
    else:
        finf_pol = x**n - y**2

    # Determine whether f is modular
    if not ((num.degree(z) > 0) or (denom.degree(z) > 0)):
        analytic_type = analytic_type.reduce_to("mero")

    # Determine whether f is holomorphic
    if (dhom(denom).is_constant()):
        analytic_type = analytic_type.reduce_to(["quasi", "holo"])
        # Determine whether f is cuspidal in the sense that finf divides it...
        # Bug in singular: finf_pol.dividess(1.0) fails over RR
        if (not dhom(num).is_constant() and finf_pol.divides(num)):
            if (n != infinity or x.divides(num)):
                analytic_type = analytic_type.reduce_to(["quasi", "cusp"])
    else:
        # -> Because of a bug with singular in some cases
        try:
            while (finf_pol.divides(denom)):
                # a simple "denom /= finf_pol" is strangely not enough for non-exact rings
                # and dividing would/may result with an element of the quotient ring of the polynomial ring
                denom = denom.quo_rem(finf_pol)[0]
                denom = R(denom)
            if (n == infinity):
                while (x.divides(denom)):
                    # a simple "denom /= x" is strangely not enough for non-exact rings
                    # and dividing would/may result with an element of the quotient ring of the polynomial ring
                    denom = denom.quo_rem(x)[0]
                    denom = R(denom)
        except TypeError:
            pass

        # Determine whether f is weakly holomorphic in the sense that at most powers of finf occur in denom
        if (dhom(denom).is_constant()):
            analytic_type = analytic_type.reduce_to(["quasi", "weak"])

    return (elem, h**o, weight, ep, analytic_type)
示例#5
0
class FormsSpaceFunctor(ConstructionFunctor):
    r"""
    Construction functor for forms spaces.

    NOTE:

    When the base ring is not a ``BaseFacade`` the functor is first
    merged with the ConstantFormsSpaceFunctor.  This case occurs in
    the pushout constructions (when trying to find a common parent
    between a forms space and a ring which is not a ``BaseFacade``).
    """

    from analytic_type import AnalyticType
    AT = AnalyticType()

    rank = 10

    def __init__(self, analytic_type, group, k, ep):
        r"""
        Construction functor for the forms space
        (or forms ring, see above) with
        the given ``analytic_type``, ``group``,
        weight ``k`` and multiplier ``ep``.

        See :meth:`__call__` for a description of the functor.

        INPUT:

        - ``analytic_type``  -- An element of ``AnalyticType()``.

        - ``group``          -- The index of a Hecke Triangle group.

        - ``k``              -- A rational number, the weight of the space.

        - ``ep``             -- `1` or `-1`, the multiplier of the space.

        OUTPUT:

        The construction functor for the corresponding forms space/ring.

        EXAMPLES::

            sage: from sage.modular.modform_hecketriangle.functors import FormsSpaceFunctor
            sage: FormsSpaceFunctor(["holo", "weak"], group=4, k=0, ep=-1)
            WeakModularFormsFunctor(n=4, k=0, ep=-1)
        """

        Functor.__init__(self, Rings(), CommutativeAdditiveGroups())
        from space import canonical_parameters
        (self._group, R, self._k, self._ep,
         n) = canonical_parameters(group, ZZ, k, ep)

        self._analytic_type = self.AT(analytic_type)

    def __call__(self, R):
        r"""
        If ``R`` is a ``BaseFacade(S)`` then return the corresponding
        forms space with base ring ``_get_base_ring(S)``.

        If not then we first merge the functor with the ConstantFormsSpaceFunctor.

        EXAMPLES::

            sage: from sage.modular.modform_hecketriangle.functors import (FormsSpaceFunctor, BaseFacade)
            sage: F = FormsSpaceFunctor(["holo", "weak"], group=4, k=0, ep=-1)
            sage: F(BaseFacade(ZZ))
            WeakModularForms(n=4, k=0, ep=-1) over Integer Ring
            sage: F(BaseFacade(CC))
            WeakModularForms(n=4, k=0, ep=-1) over Complex Field with 53 bits of precision
            sage: F(CC)
            WeakModularFormsRing(n=4) over Complex Field with 53 bits of precision
            sage: F(CC).has_reduce_hom()
            True
        """

        if (isinstance(R, BaseFacade)):
            R = _get_base_ring(R._ring)
            return FormsSpace(self._analytic_type, self._group, R, self._k,
                              self._ep)
        else:
            R = BaseFacade(_get_base_ring(R))
            merged_functor = self.merge(ConstantFormsSpaceFunctor(self._group))
            return merged_functor(R)

    def __str__(self):
        r"""
        Return the string representation of ``self``.

        EXAMPLES::

            sage: from sage.modular.modform_hecketriangle.functors import FormsSpaceFunctor
            sage: F = FormsSpaceFunctor(["cusp", "quasi"], group=5, k=10/3, ep=-1)
            sage: str(F)
            'QuasiCuspFormsFunctor(n=5, k=10/3, ep=-1)'
            sage: F
            QuasiCuspFormsFunctor(n=5, k=10/3, ep=-1)
        """

        return "{}FormsFunctor(n={}, k={}, ep={})".format(
            self._analytic_type.analytic_space_name(), self._group.n(),
            self._k, self._ep)

    def merge(self, other):
        r"""
        Return the merged functor of ``self`` and ``other``.

        It is only possible to merge instances of ``FormsSpaceFunctor``
        and ``FormsRingFunctor``. Also only if they share the same group.
        An ``FormsSubSpaceFunctors`` is replaced by its ambient space functor.

        The analytic type of the merged functor is the extension
        of the two analytic types of the functors.
        The ``red_hom`` parameter of the merged functor
        is the logical ``and`` of the two corresponding ``red_hom``
        parameters (where a forms space is assumed to have it
        set to ``True``).

        Two ``FormsSpaceFunctor`` with different (k,ep) are merged to a
        corresponding ``FormsRingFunctor``. Otherwise the corresponding
        (extended) ``FormsSpaceFunctor`` is returned.

        A ``FormsSpaceFunctor`` and ``FormsRingFunctor``
        are merged to a corresponding (extended) ``FormsRingFunctor``.

        Two ``FormsRingFunctors`` are merged to the corresponding
        (extended) ``FormsRingFunctor``.


        EXAMPLES::

            sage: from sage.modular.modform_hecketriangle.functors import (FormsSpaceFunctor, FormsRingFunctor)
            sage: functor1 = FormsSpaceFunctor("holo", group=5, k=0, ep=1)
            sage: functor2 = FormsSpaceFunctor(["quasi", "cusp"], group=5, k=10/3, ep=-1)
            sage: functor3 = FormsSpaceFunctor(["quasi", "mero"], group=5, k=0, ep=1)
            sage: functor4 = FormsRingFunctor("cusp", group=5, red_hom=False)
            sage: functor5 = FormsSpaceFunctor("holo", group=4, k=0, ep=1)

            sage: functor1.merge(functor1) is functor1
            True
            sage: functor1.merge(functor5) is None
            True
            sage: functor1.merge(functor2)
            QuasiModularFormsRingFunctor(n=5, red_hom=True)
            sage: functor1.merge(functor3)
            QuasiMeromorphicModularFormsFunctor(n=5, k=0, ep=1)
            sage: functor1.merge(functor4)
            ModularFormsRingFunctor(n=5)
        """

        if (self == other):
            return self

        if isinstance(other, FormsSubSpaceFunctor):
            other = other._ambient_space_functor

        if isinstance(other, FormsSpaceFunctor):
            if not (self._group == other._group):
                return None
            analytic_type = self._analytic_type + other._analytic_type
            if (self._k == other._k) and (self._ep == other._ep):
                return FormsSpaceFunctor(analytic_type, self._group, self._k,
                                         self._ep)
            else:
                return FormsRingFunctor(analytic_type, self._group, True)
        elif isinstance(other, FormsRingFunctor):
            if not (self._group == other._group):
                return None
            red_hom = other._red_hom
            analytic_type = self._analytic_type + other._analytic_type
            return FormsRingFunctor(analytic_type, self._group, red_hom)

    def __eq__(self, other):
        r"""
        Compare ``self`` and ``other``.

        EXAMPLES::

            sage: from sage.modular.modform_hecketriangle.functors import FormsSpaceFunctor
            sage: functor1 = FormsSpaceFunctor("holo", group=4, k=12, ep=1)
            sage: functor2 = FormsSpaceFunctor("holo", group=4, k=12, ep=-1)
            sage: functor1 == functor2
            False
        """

        if (type(self) is type(other) and self._group == other._group
                and self._analytic_type == other._analytic_type
                and self._k == other._k and self._ep == other._ep):
            return True
        else:
            return False