def _get_element_nullspace(self, M):
## We take the domain where our elements will lie
## conversion->lazy domain->domain
parent = self.__conversion.base().base()
## We assume the matrix is in the correct space
M = self.__conversion.simplify(M)
## We clean denominators to lie in the polynomial ring
lcms = [lcm([el.denominator() for el in row]) for row in M]
R = M.parent().base().base()
M = Matrix(R,
[[el * lcms[i] for el in M[i]] for i in range(M.nrows())])
f = lambda p: self.__smart_is_null(p)
try:
assert (f(1) == False)
except Exception:
raise ValueError("The method to check membership is not correct")
from sage.rings.polynomial.polynomial_ring import is_PolynomialRing as isUniPolynomial
from sage.rings.polynomial.multi_polynomial_ring import is_MPolynomialRing as isMPolynomial
## Computing the kernell of the matrix
if (isUniPolynomial(R) or isMPolynomial(R)):
bareiss_algorithm = BareissAlgorithm(R, M, f)
ker = bareiss_algorithm.syzygy().transpose()
## If some relations are found during this process, we add it to the conversion system
self.__conversion.add_relations(bareiss_algorithm.relations())
else:
ker = [v for v in M.right_kernel_matrix()]
## If the nullspace has high dimension, we try to reduce the final vector computing zeros at the end
aux = [row for row in ker]
i = 1
while (len(aux) > 1):
new = []
current = None
for j in range(len(aux)):
if (aux[j][-(i)] == 0):
new += [aux[j]]
elif (current is None):
current = j
else:
new += [
aux[current] * aux[j][-(i)] -
aux[j] * aux[current][-(i)]
]
current = j
aux = [el / gcd(el) for el in new]
i = i + 1
## When exiting the loop, aux has just one vector
sol = aux[0]
sol = [self.__conversion.simplify(a) for a in sol]
## This steps for clearing denominator are no longer needed
#lazyLcm = lcm([a.denominator() for a in sol])
#finalLazySolution = [a.numerator()*(lazyLcm/(a.denominator())) for a in sol]
## Just to be sure everything is as simple as possible, we divide again by the gcd of all our
## coefficients and simplify them using the relations known.
fin_gcd = gcd(sol)
finalSolution = [a / fin_gcd for a in sol]
finalSolution = [self.__conversion.simplify(a) for a in finalSolution]
## We transform our polynomial into elements of our destiny domain
finalSolution = [
self.__conversion.to_real(a).raw() for a in finalSolution
]
return vector(parent, finalSolution)
def _get_element_nullspace(self, M):
## We take the Conversion System
R = self.__conversion
## We assume the matrix is in the correct space
M = Matrix(R.poly_field(),
[[R.simplify(el.poly()) for el in row] for row in M])
## We clean denominators to lie in the polynomial ring
lcms = [self.__get_lcm([el.denominator() for el in row]) for row in M]
M = Matrix(R.poly_ring(),
[[el * lcms[i] for el in M[i]] for i in range(M.nrows())])
f = lambda p: R(p).is_zero()
try:
assert (f(1) == False)
except Exception:
raise ValueError("The method to check membership is not correct")
## Computing the kernell of the matrix
if (len(R.map_of_vars()) > 0):
bareiss_algorithm = BareissAlgorithm(
R.poly_ring(), M, f, R._ConversionSystem__relations)
ker = bareiss_algorithm.syzygy().transpose()
## If some relations are found during this process, we add it to the conversion system
R.add_relations(bareiss_algorithm.relations())
else:
ker = [v for v in M.right_kernel_matrix()]
## If the nullspace has high dimension, we try to reduce the final vector computing zeros at the end
aux = [row for row in ker]
i = 1
while (len(aux) > 1):
new = []
current = None
for j in range(len(aux)):
if (aux[j][-(i)] == 0):
new += [aux[j]]
elif (current is None):
current = j
else:
new += [
aux[current] * aux[j][-(i)] -
aux[j] * aux[current][-(i)]
]
current = j
aux = [el / gcd(el) for el in new]
i = i + 1
## When exiting the loop, aux has just one vector
sol = aux[0]
sol = [R.simplify(a) for a in sol]
## Just to be sure everything is as simple as possible, we divide again by the gcd of all our
## coefficients and simplify them using the relations known.
fin_gcd = gcd(sol)
finalSolution = [a / fin_gcd for a in sol]
finalSolution = [R.simplify(a) for a in finalSolution]
## We transform our polynomial into elements of our destiny domain
realSolution = [R.to_real(a) for a in finalSolution]
for i in range(len(realSolution)):
try:
realSolution[i].built = ("polynomial", (finalSolution[i], {
str(key): R.map_of_vars()[str(key)]
for key in finalSolution[i].variables()
}))
except AttributeError:
pass
return vector(R.base(), realSolution)
