def test_dimensions_of_expressions(self):
a = Quantity("a")
SI.set_quantity_dimension(a, length)
t = Quantity("t")
SI.set_quantity_dimension(t, time)
res = a**2 / t
# we can now determine the physical dimension of res
res_dim = SI.get_dimensional_expr(res)
self.assertTrue(dimsys_SI.equivalent_dims(res_dim, length**2 / time))
# In parameter dicts we can describe values along with units
a_val = Quantity("a_val")
SI.set_quantity_dimension(a_val, length)
SI.set_quantity_scale_factor(a_val, 5 * meter)
parameter_dict = {a: 5 * meter, t: 4 * second}
res_val = res.subs(parameter_dict)
# we can now determine the physical dimension of res_val
# and check it against the expected
print(SI.get_dimensional_expr(res_val))
self.assertTrue(
dimsys_SI.equivalent_dims(SI.get_dimensional_expr(res),
SI.get_dimensional_expr(res_val)))
def v_unit(t):
# Note:
# At the moment t has to be a scalar
cond_1 = simplify(t) == 0
cond_2 = dimsys_SI.equivalent_dims(SI.get_dimensional_expr(t),
time)
assert cond_1 | cond_2
omega = 2 * pi / second
# phi = 0
phi = pi / 8
V_0 = 20 * meter / second
V_range = 5 * meter / second
return V_0 + V_range * sin(omega * t + phi)
def test_Dimension_mul_div_exp():
assert 2*length == length*2 == length/2 == length
assert 2/length == 1/length
x = Symbol('x')
m = x*length
assert m == length*x and m.is_Mul and set(m.args) == {x, length}
d = x/length
assert d == x*length**-1 and d.is_Mul and set(d.args) == {x, 1/length}
d = length/x
assert d == length*x**-1 and d.is_Mul and set(d.args) == {1/x, length}
velo = length / time
assert (length * length) == length ** 2
assert dimsys_SI.get_dimensional_dependencies(length * length) == {"length": 2}
assert dimsys_SI.get_dimensional_dependencies(length ** 2) == {"length": 2}
assert dimsys_SI.get_dimensional_dependencies(length * time) == { "length": 1, "time": 1}
assert dimsys_SI.get_dimensional_dependencies(velo) == { "length": 1, "time": -1}
assert dimsys_SI.get_dimensional_dependencies(velo ** 2) == {"length": 2, "time": -2}
assert dimsys_SI.get_dimensional_dependencies(length / length) == {}
assert dimsys_SI.get_dimensional_dependencies(velo / length * time) == {}
assert dimsys_SI.get_dimensional_dependencies(length ** -1) == {"length": -1}
assert dimsys_SI.get_dimensional_dependencies(velo ** -1.5) == {"length": -1.5, "time": 1.5}
length_a = length**"a"
assert dimsys_SI.get_dimensional_dependencies(length_a) == {"length": Symbol("a")}
assert length != 1
assert length / length != 1
length_0 = length ** 0
assert dimsys_SI.get_dimensional_dependencies(length_0) == {}
# issue 18738
a = Symbol('a')
b = Symbol('b')
c = sqrt(a**2 + b**2)
c_dim = c.subs({a: length, b: length})
assert dimsys_SI.equivalent_dims(c_dim, length)