def test_no_exception_raised_passing_christoffel_with_unconventional_indices():
sch = schwarzschild_metric()
ch = ChristoffelSymbols.from_metric(sch)
ch2 = ch.change_config("uuu")
try:
rm = RiemannCurvatureTensor.from_christoffels(ch2)
assert True
except:
assert False
def test_properties():
sch_inv = schwarzschild_metric()
ch = ChristoffelSymbols.from_metric(sch_inv)
assert ch.parent_metric == ch._parent_metric
# test change_config, should raise ValueError
ch._parent_metric = None
try:
ch_new = ch.change_config("lll")
assert False
except Exception:
return True
def get_christoffel_symbols(self, input_vectors=None):
"""
returns the christoffel symbols in the standard order:
`cf[i,j,k]`= $\Gamma^i_{jk}$
einsteinpy is used to obtain the tensor
"""
cf = ChristoffelSymbols.from_metric(self.get_metric_tensor())
if input_vectors is not None:
cf = self.model.apply(cf.tensor(), input_vectors)
return cf
def test_ChristoffelSymbols():
sch = schwarzschild_metric()
chl = ChristoffelSymbols.from_metric(sch)
mat = chl.tensor()
symbolstr = "t r theta phi"
syms = sympy.symbols(symbolstr)
G, M, c, a = sympy.symbols("G M c a")
assert (
sympy.simplify(mat[2, 3, 3] -
(-1 * sympy.cos(syms[2]) * sympy.sin(syms[2]))) == 0)
assert sympy.simplify(mat[3, 3, 1] - syms[1] / (syms[1]**2)) == 0
assert (sympy.simplify((mat[1, 1, 1].subs({a: (2 * G * M / (c**2))})) -
(G * M /
(2 * G * M * syms[1] - c**2 * syms[1]**2))) == 0)
assert chl.symbols() == syms
def christoffel_symbol(self):
from einsteinpy.symbolic import ChristoffelSymbols
return ChristoffelSymbols.from_metric(self.metric_tensor)
def get_tensor():
metric = AntiDeSitter()
return ChristoffelSymbols.from_metric(metric)