def test_correct_arguments():
raises(ValueError, lambda: R2.e_x(R2.e_x))
raises(ValueError, lambda: R2.e_x(R2.dx))
raises(ValueError, lambda: Commutator(R2.e_x, R2.x))
raises(ValueError, lambda: Commutator(R2.dx, R2.e_x))
raises(ValueError, lambda: Differential(Differential(R2.e_x)))
raises(ValueError, lambda: R2.dx(R2.x))
raises(ValueError, lambda: LieDerivative(R2.dx, R2.dx))
raises(ValueError, lambda: LieDerivative(R2.x, R2.dx))
raises(ValueError, lambda: CovarDerivativeOp(R2.dx, []))
raises(ValueError, lambda: CovarDerivativeOp(R2.x, []))
a = Symbol('a')
raises(ValueError, lambda: intcurve_series(R2.dx, a, R2_r.point([1, 2])))
raises(ValueError, lambda: intcurve_series(R2.x, a, R2_r.point([1, 2])))
raises(ValueError, lambda: intcurve_diffequ(R2.dx, a, R2_r.point([1, 2])))
raises(ValueError, lambda: intcurve_diffequ(R2.x, a, R2_r.point([1, 2])))
raises(ValueError, lambda: contravariant_order(R2.e_x + R2.dx))
raises(ValueError, lambda: covariant_order(R2.e_x + R2.dx))
raises(ValueError, lambda: contravariant_order(R2.e_x * R2.e_y))
raises(ValueError, lambda: covariant_order(R2.dx * R2.dy))
def test_correct_arguments():
raises(ValueError, lambda : R2.e_x(R2.e_x))
raises(ValueError, lambda : R2.e_x(R2.dx))
raises(ValueError, lambda : Commutator(R2.e_x, R2.x))
raises(ValueError, lambda : Commutator(R2.dx, R2.e_x))
raises(ValueError, lambda : Differential(Differential(R2.e_x)))
raises(ValueError, lambda : R2.dx(R2.x))
raises(ValueError, lambda : TensorProduct(R2.e_x, R2.dx))
raises(ValueError, lambda : LieDerivative(R2.dx, R2.dx))
raises(ValueError, lambda : LieDerivative(R2.x, R2.dx))
raises(ValueError, lambda : CovarDerivativeOp(R2.dx, []))
raises(ValueError, lambda : CovarDerivativeOp(R2.x, []))
a = Symbol('a')
raises(ValueError, lambda : intcurve_series(R2.dx, a, R2_r.point([1,2])))
raises(ValueError, lambda : intcurve_series(R2.x, a, R2_r.point([1,2])))
raises(ValueError, lambda : intcurve_diffequ(R2.dx, a, R2_r.point([1,2])))
raises(ValueError, lambda : intcurve_diffequ(R2.x, a, R2_r.point([1,2])))
raises(ValueError, lambda : contravariant_order(R2.e_x + R2.dx))
raises(ValueError, lambda : covariant_order(R2.e_x + R2.dx))
raises(ValueError, lambda : contravariant_order(R2.e_x*R2.e_y))
raises(ValueError, lambda : covariant_order(R2.dx*R2.dy))
def test_functional_diffgeom_ch3():
x0, y0 = symbols('x0, y0', real=True)
x, y, t = symbols('x, y, t', real=True)
f = Function('f')
b1 = Function('b1')
b2 = Function('b2')
p_r = R2_r.point([x0, y0])
s_field = f(R2.x, R2.y)
v_field = b1(R2.x)*R2.e_x + b2(R2.y)*R2.e_y
assert v_field.rcall(s_field).rcall(p_r).doit() == b1(
x0)*Derivative(f(x0, y0), x0) + b2(y0)*Derivative(f(x0, y0), y0)
assert R2.e_x(R2.r**2).rcall(p_r) == 2*x0
v = R2.e_x + 2*R2.e_y
s = R2.r**2 + 3*R2.x
assert v.rcall(s).rcall(p_r).doit() == 2*x0 + 4*y0 + 3
circ = -R2.y*R2.e_x + R2.x*R2.e_y
series = intcurve_series(circ, t, R2_r.point([1, 0]), coeffs=True)
series_x, series_y = zip(*series)
assert all(
[term == cos(t).taylor_term(i, t) for i, term in enumerate(series_x)])
assert all(
[term == sin(t).taylor_term(i, t) for i, term in enumerate(series_y)])
def test_functional_diffgeom_ch3():
x0, y0 = symbols('x0, y0', real=True)
x, y, t = symbols('x, y, t', real=True)
f = Function('f')
b1 = Function('b1')
b2 = Function('b2')
p_r = R2_r.point([x0, y0])
s_field = f(R2.x, R2.y)
v_field = b1(R2.x)*R2.e_x + b2(R2.y)*R2.e_y
assert v_field.rcall(s_field).rcall(p_r).doit() == b1(
x0)*Derivative(f(x0, y0), x0) + b2(y0)*Derivative(f(x0, y0), y0)
assert R2.e_x(R2.r**2).rcall(p_r) == 2*x0
v = R2.e_x + 2*R2.e_y
s = R2.r**2 + 3*R2.x
assert v.rcall(s).rcall(p_r).doit() == 2*x0 + 4*y0 + 3
circ = -R2.y*R2.e_x + R2.x*R2.e_y
series = intcurve_series(circ, t, R2_r.point([1, 0]), coeffs=True)
series_x, series_y = zip(*series)
assert all(
[term == cos(t).taylor_term(i, t) for i, term in enumerate(series_x)])
assert all(
[term == sin(t).taylor_term(i, t) for i, term in enumerate(series_y)])
from sympy.diffgeom import metric_to_Christoffel_2nd, TensorProduct TP = TensorProduct ch = metric_to_Christoffel_2nd(TP(R2.dx, R2.dx) + TP(R2.dy, R2.dy)) ch cvd = CovarDerivativeOp(R2.x*R2.e_x, ch) cvd(R2.x) cvd(R2.x*R2.e_x) #intcurve_series from sympy.abc import t, x, y from sympy.diffgeom.rn import R2, R2_p, R2_r from sympy.diffgeom import intcurve_series # Specify a starting point and a vector field: start_point = R2_r.point([x, y]) vector_field = R2_r.e_x # Calculate the series: intcurve_series(vector_field, t, start_point, n=3) # Or get the elements of the expansion in a list: series = intcurve_series(vector_field, t, start_point, n=3, coeffs=True) series[0] series[1] series[2] #intcurve_diffequ from sympy.abc import t from sympy.diffgeom.rn import R2, R2_p, R2_r from sympy.diffgeom import intcurve_diffequ #Specify a starting point and a vector field: start_point = R2_r.point([0, 1]) vector_field = -R2.y*R2.e_x + R2.x*R2.e_y # get the equations, equations, init_cond = intcurve_diffequ(vector_field, t, start_point) equations
