DeRhamComputation/as_covers/as_function_class.sage

191 lines
6.0 KiB
Python

class as_function:
def __init__(self, C, g):
self.curve = C
F = C.base_ring
n = C.height
RxyzQ, Rxyz, x, y, z = C.fct_field
self.function = RxyzQ(g)
#self.function = as_reduction(AS, RxyzQ(g))
def __repr__(self):
return str(self.function)
def __eq__(self, other):
AS = self.curve
RxyzQ, Rxyz, x, y, z = AS.fct_field
aux = self - other
aux = RxyzQ(aux.function)
aux = aux.numerator()
aux = as_function(AS, aux)
aux = aux.expansion_at_infty()
if aux.valuation() >= 1:
return True
return False
def __add__(self, other):
C = self.curve
g1 = self.function
g2 = other.function
return as_function(C, g1 + g2)
def __sub__(self, other):
C = self.curve
g1 = self.function
g2 = other.function
return as_function(C, g1 - g2)
def __rmul__(self, constant):
C = self.curve
g = self.function
return as_function(C, constant*g)
def __neg__(self):
C = self.curve
g = self.function
return as_function(C, -g)
def __mul__(self, other):
if isinstance(other, as_function):
C = self.curve
g1 = self.function
g2 = other.function
return as_function(C, g1*g2)
if isinstance(other, as_form):
C = self.curve
g1 = self.function
g2 = other.form
return as_form(C, g1*g2)
def __truediv__(self, other):
C = self.curve
g1 = self.function
g2 = other.function
return as_function(C, g1/g2)
def __pow__(self, exponent):
C = self.curve
g1 = self.function
return as_function(C, g1^(exponent))
def expansion_at_infty(self, place = 0):
C = self.curve
delta = C.nb_of_pts_at_infty
F = C.base_ring
x_series = C.x_series[place]
y_series = C.y_series[place]
z_series = C.z_series[place]
n = C.height
RxyzQ, Rxyz, x, y, z = C.fct_field
prec = C.prec
Rt.<t> = LaurentSeriesRing(F, default_prec=prec)
g = self.function
g = RxyzQ(g)
sub_list = {x : x_series, y : y_series} | {z[j] : z_series[j] for j in range(n)}
return g.substitute(sub_list)
def expansion(self, pt = 0):
C = self.curve
delta = C.nb_of_pts_at_infty
F = C.base_ring
x_series = C.x_series[pt]
y_series = C.y_series[pt]
z_series = C.z_series[pt]
n = C.height
RxyzQ, Rxyz, x, y, z = C.fct_field
prec = C.prec
Rt.<t> = LaurentSeriesRing(F, default_prec=prec)
g = self.function
g = RxyzQ(g)
sub_list = {x : x_series, y : y_series} | {z[j] : z_series[j] for j in range(n)}
return g.substitute(sub_list)
def group_action(self, elt):
C = self.curve
RxyzQ, Rxyz, x, y, z = C.fct_field
Rzf, zgen, fgen = C.cover_template.fct_field
if isinstance(elt, group_elt):
elt = elt.as_tuple
AS = self.curve
n = AS.height
G = AS.group
if elt in G.gens:
ind = G.gens.index(elt)
gp_action_list = C.cover_template.gp_action[ind]
sub_list = {x : x, y : y} | {z[j] : Rxyz(gp_action_list[j].subs({zgen[i] : z[i] for i in range(n)})) for j in range(n)}
g = self.function
return as_function(C, g.substitute(sub_list))
result = self
for i in range(len(G.gens)):
if isinstance(elt, list): #elt can be a tuple...
range_limit = elt[i]
else: # ... or an integer.
range_limit = elt
for j in range(range_limit):
print(G.gens[i])
result = result.group_action(G.gens[i])
return result
def reduce(self):
aux = as_reduction(self.curve, self.function)
return as_function(self.curve, aux)
def trace(self, super=True):
C = self.curve
C_super = C.quotient
n = C.height
F = C.base_ring
RxyzQ, Rxyz, x, y, z = C.fct_field
result = as_function(C, 0)
G = C.group.elts
for a in G:
result += self.group_action(a)
result = result.function
Rxy.<x, y> = PolynomialRing(F, 2)
Qxy = FractionField(Rxy)
result = as_reduction(C, result)
if super:
return superelliptic_function(C_super, Qxy(result))
return as_function(AS, Qxy(result))
def coordinates(self, prec = 100, basis = 0):
"Return coordinates in H^1(X, OX)."
AS = self.curve
if basis == 0:
basis = [AS.holomorphic_differentials_basis(), AS.cohomology_of_structure_sheaf_basis()]
holo_diffs = basis[0]
coh_basis = basis[1]
f_products = []
for f in coh_basis:
f_products += [[omega.serre_duality_pairing(f) for omega in holo_diffs]]
product_of_fct_and_omegas = []
product_of_fct_and_omegas = [omega.serre_duality_pairing(self) for omega in holo_diffs]
V = (F^(AS.genus())).span_of_basis([vector(a) for a in f_products])
coh_coordinates = V.coordinates(product_of_fct_and_omegas)
return coh_coordinates
def diffn(self):
C = self.curve
C_super = C.quotient
n = C.height
RxyzQ, Rxyz, x, y, z = C.fct_field
f = self.function
y_super = superelliptic_function(C_super, y)
dy_super = y_super.diffn().form
dz = C.dz
result = f.derivative(x)
result += f.derivative(y)*dy_super
for i in range(n):
result += f.derivative(z[i])*dz[i]
return as_form(C, result)
def valuation(self, place = 0):
'''Return valuation at i-th place at infinity.'''
C = self.curve
F = C.base_ring
Rt.<t> = LaurentSeriesRing(F)
return Rt(self.expansion_at_infty(place = place)).valuation()