def expand(self, **hints):
expr = self.args[0]
condition = self._condition
if not is_random(expr):
return expr
if isinstance(expr, Add):
return Add.fromiter(
Expectation(a, condition=condition).expand()
for a in expr.args)
expand_expr = _expand(expr)
if isinstance(expand_expr, Add):
return Add.fromiter(
Expectation(a, condition=condition).expand()
for a in expand_expr.args)
elif isinstance(expr, Mul):
rv = []
nonrv = []
for a in expr.args:
if is_random(a):
rv.append(a)
else:
nonrv.append(a)
return Mul.fromiter(nonrv) * Expectation(Mul.fromiter(rv),
condition=condition)
return self
def cancel_terms(sym, x_term, coef):
if coef.is_Add:
for arg_c in coef.args:
sym = cancel_terms(sym, x_term, arg_c)
else:
terms = Add.make_args(sym)
return Add.fromiter(t for t in terms if t != x_term*coef)
def expand(self, **hints):
arg1 = self.args[0]
arg2 = self.args[1]
condition = self._condition
if arg1 == arg2:
return Variance(arg1, condition).expand()
if not is_random(arg1):
return S.Zero
if not is_random(arg2):
return S.Zero
arg1, arg2 = sorted([arg1, arg2], key=default_sort_key)
if isinstance(arg1, RandomSymbol) and isinstance(arg2, RandomSymbol):
return Covariance(arg1, arg2, condition)
coeff_rv_list1 = self._expand_single_argument(arg1.expand())
coeff_rv_list2 = self._expand_single_argument(arg2.expand())
addends = [
a * b * Covariance(*sorted([r1, r2], key=default_sort_key),
condition=condition)
for (a, r1) in coeff_rv_list1 for (b, r2) in coeff_rv_list2
]
return Add.fromiter(addends)
def _eval_derivative(self, x):
from sympy import Add
terms = []
args = list(self.args)
for i in range(len(args)):
factors = args[:i] + [args[i].diff(x)] + args[i+1:]
terms.append(hadamard_product(*factors))
return Add.fromiter(terms)
def _print_Add(self, expr):
if len(expr.args) != 2:
return "add({}, {})".format(
self._print(expr.args[0]),
self._print(Add.fromiter(expr.args[1:])))
return "add({}, {})".format(
self._print(expr.args[0]),
self._print(expr.args[1]),
)
def _print_Add(self, expr):
if len(expr.args) != 2:
return "add({}, {})".format(
self._print(expr.args[0]),
self._print(Add.fromiter(expr.args[1:]))
)
return "add({}, {})".format(
self._print(expr.args[0]),
self._print(expr.args[1]),
)
def expand(self, **hints):
expr = self.args[0]
condition = self._condition
if not is_random(expr):
return expr
if isinstance(expr, Add):
return Add.fromiter(
Expectation(a, condition=condition).expand()
for a in expr.args)
expand_expr = _expand(expr)
if isinstance(expand_expr, Add):
return Add.fromiter(
Expectation(a, condition=condition).expand()
for a in expand_expr.args)
elif isinstance(expr, (Mul, MatMul)):
rv = []
nonrv = []
postnon = []
for a in expr.args:
if is_random(a):
if rv:
rv.extend(postnon)
else:
nonrv.extend(postnon)
postnon = []
rv.append(a)
elif a.is_Matrix:
postnon.append(a)
else:
nonrv.append(a)
# In order to avoid infinite-looping (MatMul may call .doit() again),
# do not rebuild
if len(nonrv) == 0:
return self
return Mul.fromiter(nonrv) * Expectation(
Mul.fromiter(rv), condition=condition) * Mul.fromiter(postnon)
return self
def dot(vect1, vect2):
"""
Returns dot product of two vectors.
Examples
========
>>> from sympy.vector import CoordSys3D
>>> from sympy.vector.vector import dot
>>> R = CoordSys3D('R')
>>> v1 = R.i + R.j + R.k
>>> v2 = R.x * R.i + R.y * R.j + R.z * R.k
>>> dot(v1, v2)
R.x + R.y + R.z
"""
if isinstance(vect1, Add):
return Add.fromiter(dot(i, vect2) for i in vect1.args)
if isinstance(vect2, Add):
return Add.fromiter(dot(vect1, i) for i in vect2.args)
if isinstance(vect1, BaseVector) and isinstance(vect2, BaseVector):
if vect1._sys == vect2._sys:
return S.One if vect1 == vect2 else S.Zero
from .functions import express
try:
v = express(vect2, vect1._sys)
except ValueError:
return Dot(vect1, vect2)
else:
return dot(vect1, v)
if isinstance(vect1, VectorZero) or isinstance(vect2, VectorZero):
return S.Zero
if isinstance(vect1, VectorMul):
v1, m1 = next(iter(vect1.components.items()))
return m1 * dot(v1, vect2)
if isinstance(vect2, VectorMul):
v2, m2 = next(iter(vect2.components.items()))
return m2 * dot(vect1, v2)
return Dot(vect1, vect2)
def dot(vect1, vect2):
"""
Returns dot product of two vectors.
Examples
========
>>> from sympy.vector import CoordSys3D
>>> from sympy.vector.vector import dot
>>> R = CoordSys3D('R')
>>> v1 = R.i + R.j + R.k
>>> v2 = R.x * R.i + R.y * R.j + R.z * R.k
>>> dot(v1, v2)
R.x + R.y + R.z
"""
if isinstance(vect1, Add):
return Add.fromiter(dot(i, vect2) for i in vect1.args)
if isinstance(vect2, Add):
return Add.fromiter(dot(vect1, i) for i in vect2.args)
if isinstance(vect1, BaseVector) and isinstance(vect2, BaseVector):
if vect1._sys == vect2._sys:
return S.One if vect1 == vect2 else S.Zero
try:
from .functions import express
return dot(vect1, express(vect2, vect1._sys))
except:
return Dot(vect1, vect2)
if isinstance(vect1, VectorZero) or isinstance(vect2, VectorZero):
return S.Zero
if isinstance(vect1, VectorMul):
v1, m1 = next(iter(vect1.components.items()))
return m1*dot(v1, vect2)
if isinstance(vect2, VectorMul):
v2, m2 = next(iter(vect2.components.items()))
return m2*dot(vect1, v2)
return Dot(vect1, vect2)
def expand(self, **hints):
arg1 = self.args[0]
arg2 = self.args[1]
condition = self._condition
if arg1 == arg2:
return VarianceMatrix(arg1, condition).expand()
if not is_random(arg1) or not is_random(arg2):
return ZeroMatrix(*self.shape)
if isinstance(arg1, RandomSymbol) and isinstance(arg2, RandomSymbol):
return CrossCovarianceMatrix(arg1, arg2, condition)
coeff_rv_list1 = self._expand_single_argument(arg1.expand())
coeff_rv_list2 = self._expand_single_argument(arg2.expand())
addends = [a*CrossCovarianceMatrix(r1, r2, condition=condition)*b.transpose()
for (a, r1) in coeff_rv_list1 for (b, r2) in coeff_rv_list2]
return Add.fromiter(addends)
def convert_to(expr, target_units):
"""
Convert ``expr`` to the same expression with all of its units and quantities
represented as factors of ``target_units``, whenever the dimension is compatible.
``target_units`` may be a single unit/quantity, or a collection of
units/quantities.
Examples
========
>>> from sympy.physics.units import speed_of_light, meter, gram, second, day
>>> from sympy.physics.units import mile, newton, kilogram, atomic_mass_constant
>>> from sympy.physics.units import kilometer, centimeter
>>> from sympy.physics.units import convert_to
>>> convert_to(mile, kilometer)
25146*kilometer/15625
>>> convert_to(mile, kilometer).n()
1.609344*kilometer
>>> convert_to(speed_of_light, meter/second)
299792458*meter/second
>>> convert_to(day, second)
86400*second
>>> 3*newton
3*newton
>>> convert_to(3*newton, kilogram*meter/second**2)
3*kilogram*meter/second**2
>>> convert_to(atomic_mass_constant, gram)
1.66053904e-24*gram
Conversion to multiple units:
>>> convert_to(speed_of_light, [meter, second])
299792458*meter/second
>>> convert_to(3*newton, [centimeter, gram, second])
300000*centimeter*gram/second**2
Conversion to Planck units:
>>> from sympy.physics.units import gravitational_constant, hbar
>>> convert_to(atomic_mass_constant, [gravitational_constant, speed_of_light, hbar]).n()
7.62950196312651e-20*gravitational_constant**(-0.5)*hbar**0.5*speed_of_light**0.5
"""
if not isinstance(target_units, (collections.Iterable, Tuple)):
target_units = [target_units]
if isinstance(expr, Add):
return Add.fromiter(convert_to(i, target_units) for i in expr.args)
expr = sympify(expr)
if not isinstance(expr, Quantity) and expr.has(Quantity):
expr = expr.replace(lambda x: isinstance(x, Quantity), lambda x: x.convert_to(target_units))
def get_total_scale_factor(expr):
if isinstance(expr, Mul):
return reduce(lambda x, y: x * y, [get_total_scale_factor(i) for i in expr.args])
elif isinstance(expr, Pow):
return get_total_scale_factor(expr.base) ** expr.exp
elif isinstance(expr, Quantity):
return expr.scale_factor
return expr
depmat = _get_conversion_matrix_for_expr(expr, target_units)
if depmat is None:
return expr
expr_scale_factor = get_total_scale_factor(expr)
return expr_scale_factor * Mul.fromiter((1/get_total_scale_factor(u) * u) ** p for u, p in zip(target_units, depmat))
def recurse_expr(expr, index_ranges={}):
if expr.is_Mul:
nonmatargs = []
pos_arg = []
pos_ind = []
dlinks = {}
link_ind = []
counter = 0
args_ind = []
for arg in expr.args:
retvals = recurse_expr(arg, index_ranges)
assert isinstance(retvals, list)
if isinstance(retvals, list):
for i in retvals:
args_ind.append(i)
else:
args_ind.append(retvals)
for arg_symbol, arg_indices in args_ind:
if arg_indices is None:
nonmatargs.append(arg_symbol)
continue
if isinstance(arg_symbol, MatrixElement):
arg_symbol = arg_symbol.args[0]
pos_arg.append(arg_symbol)
pos_ind.append(arg_indices)
link_ind.append([None] * len(arg_indices))
for i, ind in enumerate(arg_indices):
if ind in dlinks:
other_i = dlinks[ind]
link_ind[counter][i] = other_i
link_ind[other_i[0]][other_i[1]] = (counter, i)
dlinks[ind] = (counter, i)
counter += 1
counter2 = 0
lines = {}
while counter2 < len(link_ind):
for i, e in enumerate(link_ind):
if None in e:
line_start_index = (i, e.index(None))
break
cur_ind_pos = line_start_index
cur_line = []
index1 = pos_ind[cur_ind_pos[0]][cur_ind_pos[1]]
while True:
d, r = cur_ind_pos
if pos_arg[d] != 1:
if r % 2 == 1:
cur_line.append(transpose(pos_arg[d]))
else:
cur_line.append(pos_arg[d])
next_ind_pos = link_ind[d][1 - r]
counter2 += 1
# Mark as visited, there will be no `None` anymore:
link_ind[d] = (-1, -1)
if next_ind_pos is None:
index2 = pos_ind[d][1 - r]
lines[(index1, index2)] = cur_line
break
cur_ind_pos = next_ind_pos
ret_indices = list(j for i in lines for j in i)
lines = {
k: MatMul.fromiter(v) if len(v) != 1 else v[0]
for k, v in lines.items()
}
return [(Mul.fromiter(nonmatargs), None)] + [(MatrixElement(
a, i, j), (i, j)) for (i, j), a in lines.items()]
elif expr.is_Add:
res = [recurse_expr(i) for i in expr.args]
d = collections.defaultdict(list)
for res_addend in res:
scalar = 1
for elem, indices in res_addend:
if indices is None:
scalar = elem
continue
indices = tuple(sorted(indices, key=default_sort_key))
d[indices].append(scalar *
remove_matelement(elem, *indices))
scalar = 1
return [(MatrixElement(Add.fromiter(v), *k), k)
for k, v in d.items()]
elif isinstance(expr, KroneckerDelta):
i1, i2 = expr.args
return [(MatrixElement(S.One, i1, i2), (i1, i2))]
elif isinstance(expr, MatrixElement):
matrix_symbol, i1, i2 = expr.args
if i1 in index_ranges:
r1, r2 = index_ranges[i1]
if r1 != 0 or matrix_symbol.shape[0] != r2 + 1:
raise ValueError(
"index range mismatch: {0} vs. (0, {1})".format(
(r1, r2), matrix_symbol.shape[0]))
if i2 in index_ranges:
r1, r2 = index_ranges[i2]
if r1 != 0 or matrix_symbol.shape[1] != r2 + 1:
raise ValueError(
"index range mismatch: {0} vs. (0, {1})".format(
(r1, r2), matrix_symbol.shape[1]))
if (i1 == i2) and (i1 in index_ranges):
return [(trace(matrix_symbol), None)]
return [(MatrixElement(matrix_symbol, i1, i2), (i1, i2))]
elif isinstance(expr, Sum):
return recurse_expr(
expr.args[0],
index_ranges={i[0]: i[1:]
for i in expr.args[1:]})
else:
return [(expr, None)]
def get_max_coef(sym, x_term):
return Add.fromiter(
get_max_coef_mul(s, x_term) for s in Add.make_args(sym)
)
def divergence(vect, coord_sys=None, doit=True):
"""
Returns the divergence of a vector field computed wrt the base
scalars of the given coordinate system.
Parameters
==========
vector : Vector
The vector operand
coord_sys : CoordSys3D
The coordinate system to calculate the gradient in
Deprecated since version 1.1
doit : bool
If True, the result is returned after calling .doit() on
each component. Else, the returned expression contains
Derivative instances
Examples
========
>>> from sympy.vector import CoordSys3D, divergence
>>> R = CoordSys3D('R')
>>> v1 = R.x*R.y*R.z * (R.i+R.j+R.k)
>>> divergence(v1)
R.x*R.y + R.x*R.z + R.y*R.z
>>> v2 = 2*R.y*R.z*R.j
>>> divergence(v2)
2*R.z
"""
coord_sys = _get_coord_sys_from_expr(vect, coord_sys)
if len(coord_sys) == 0:
return S.Zero
elif len(coord_sys) == 1:
if isinstance(vect, (Cross, Curl, Gradient)):
return Divergence(vect)
# TODO: is case of many coord systems, this gets a random one:
coord_sys = next(iter(coord_sys))
i, j, k = coord_sys.base_vectors()
x, y, z = coord_sys.base_scalars()
h1, h2, h3 = coord_sys.lame_coefficients()
vx = _diff_conditional(vect.dot(i), x, h2, h3) \
/ (h1 * h2 * h3)
vy = _diff_conditional(vect.dot(j), y, h3, h1) \
/ (h1 * h2 * h3)
vz = _diff_conditional(vect.dot(k), z, h1, h2) \
/ (h1 * h2 * h3)
res = vx + vy + vz
if doit:
return res.doit()
return res
else:
if isinstance(vect, (Add, VectorAdd)):
return Add.fromiter(divergence(i, doit=doit) for i in vect.args)
elif isinstance(vect, (Mul, VectorMul)):
vector = [i for i in vect.args if isinstance(i, (Vector, Cross, Gradient))][0]
scalar = Mul.fromiter(i for i in vect.args if not isinstance(i, (Vector, Cross, Gradient)))
res = Dot(vector, gradient(scalar)) + scalar*divergence(vector, doit=doit)
if doit:
return res.doit()
return res
elif isinstance(vect, (Cross, Curl, Gradient)):
return Divergence(vect)
else:
raise Divergence(vect)
def recurse_expr(expr, index_ranges={}):
if expr.is_Mul:
nonmatargs = []
pos_arg = []
pos_ind = []
dlinks = {}
link_ind = []
counter = 0
args_ind = []
for arg in expr.args:
retvals = recurse_expr(arg, index_ranges)
assert isinstance(retvals, list)
if isinstance(retvals, list):
for i in retvals:
args_ind.append(i)
else:
args_ind.append(retvals)
for arg_symbol, arg_indices in args_ind:
if arg_indices is None:
nonmatargs.append(arg_symbol)
continue
if isinstance(arg_symbol, MatrixElement):
arg_symbol = arg_symbol.args[0]
pos_arg.append(arg_symbol)
pos_ind.append(arg_indices)
link_ind.append([None]*len(arg_indices))
for i, ind in enumerate(arg_indices):
if ind in dlinks:
other_i = dlinks[ind]
link_ind[counter][i] = other_i
link_ind[other_i[0]][other_i[1]] = (counter, i)
dlinks[ind] = (counter, i)
counter += 1
counter2 = 0
lines = {}
while counter2 < len(link_ind):
for i, e in enumerate(link_ind):
if None in e:
line_start_index = (i, e.index(None))
break
cur_ind_pos = line_start_index
cur_line = []
index1 = pos_ind[cur_ind_pos[0]][cur_ind_pos[1]]
while True:
d, r = cur_ind_pos
if pos_arg[d] != 1:
if r % 2 == 1:
cur_line.append(transpose(pos_arg[d]))
else:
cur_line.append(pos_arg[d])
next_ind_pos = link_ind[d][1-r]
counter2 += 1
# Mark as visited, there will be no `None` anymore:
link_ind[d] = (-1, -1)
if next_ind_pos is None:
index2 = pos_ind[d][1-r]
lines[(index1, index2)] = cur_line
break
cur_ind_pos = next_ind_pos
ret_indices = list(j for i in lines for j in i)
lines = {k: MatMul.fromiter(v) if len(v) != 1 else v[0] for k, v in lines.items()}
return [(Mul.fromiter(nonmatargs), None)] + [
(MatrixElement(a, i, j), (i, j)) for (i, j), a in lines.items()
]
elif expr.is_Add:
res = [recurse_expr(i) for i in expr.args]
d = collections.defaultdict(list)
for res_addend in res:
scalar = 1
for elem, indices in res_addend:
if indices is None:
scalar = elem
continue
indices = tuple(sorted(indices, key=default_sort_key))
d[indices].append(scalar*remove_matelement(elem, *indices))
scalar = 1
return [(MatrixElement(Add.fromiter(v), *k), k) for k, v in d.items()]
elif isinstance(expr, KroneckerDelta):
i1, i2 = expr.args
if dimensions is not None:
identity = Identity(dimensions[0])
else:
identity = S.One
return [(MatrixElement(identity, i1, i2), (i1, i2))]
elif isinstance(expr, MatrixElement):
matrix_symbol, i1, i2 = expr.args
if i1 in index_ranges:
r1, r2 = index_ranges[i1]
if r1 != 0 or matrix_symbol.shape[0] != r2+1:
raise ValueError("index range mismatch: {0} vs. (0, {1})".format(
(r1, r2), matrix_symbol.shape[0]))
if i2 in index_ranges:
r1, r2 = index_ranges[i2]
if r1 != 0 or matrix_symbol.shape[1] != r2+1:
raise ValueError("index range mismatch: {0} vs. (0, {1})".format(
(r1, r2), matrix_symbol.shape[1]))
if (i1 == i2) and (i1 in index_ranges):
return [(trace(matrix_symbol), None)]
return [(MatrixElement(matrix_symbol, i1, i2), (i1, i2))]
elif isinstance(expr, Sum):
return recurse_expr(
expr.args[0],
index_ranges={i[0]: i[1:] for i in expr.args[1:]}
)
else:
return [(expr, None)]
def convert_to(expr, target_units, unit_system="SI"):
"""
Convert ``expr`` to the same expression with all of its units and quantities
represented as factors of ``target_units``, whenever the dimension is compatible.
``target_units`` may be a single unit/quantity, or a collection of
units/quantities.
Examples
========
>>> from sympy.physics.units import speed_of_light, meter, gram, second, day
>>> from sympy.physics.units import mile, newton, kilogram, atomic_mass_constant
>>> from sympy.physics.units import kilometer, centimeter
>>> from sympy.physics.units import gravitational_constant, hbar
>>> from sympy.physics.units import convert_to
>>> convert_to(mile, kilometer)
25146*kilometer/15625
>>> convert_to(mile, kilometer).n()
1.609344*kilometer
>>> convert_to(speed_of_light, meter/second)
299792458*meter/second
>>> convert_to(day, second)
86400*second
>>> 3*newton
3*newton
>>> convert_to(3*newton, kilogram*meter/second**2)
3*kilogram*meter/second**2
>>> convert_to(atomic_mass_constant, gram)
1.660539060e-24*gram
Conversion to multiple units:
>>> convert_to(speed_of_light, [meter, second])
299792458*meter/second
>>> convert_to(3*newton, [centimeter, gram, second])
300000*centimeter*gram/second**2
Conversion to Planck units:
>>> from sympy.physics.units import gravitational_constant, hbar
>>> convert_to(atomic_mass_constant, [gravitational_constant, speed_of_light, hbar]).n()
7.62963085040767e-20*gravitational_constant**(-0.5)*hbar**0.5*speed_of_light**0.5
"""
from sympy.physics.units import UnitSystem
unit_system = UnitSystem.get_unit_system(unit_system)
if not isinstance(target_units, (Iterable, Tuple)):
target_units = [target_units]
if isinstance(expr, Add):
return Add.fromiter(
convert_to(i, target_units, unit_system) for i in expr.args)
expr = sympify(expr)
if not isinstance(expr, Quantity) and expr.has(Quantity):
expr = expr.replace(lambda x: isinstance(x, Quantity),
lambda x: x.convert_to(target_units, unit_system))
def get_total_scale_factor(expr):
if isinstance(expr, Mul):
return reduce(lambda x, y: x * y,
[get_total_scale_factor(i) for i in expr.args])
elif isinstance(expr, Pow):
return get_total_scale_factor(expr.base)**expr.exp
elif isinstance(expr, Quantity):
return unit_system.get_quantity_scale_factor(expr)
return expr
depmat = _get_conversion_matrix_for_expr(expr, target_units, unit_system)
if depmat is None:
return expr
expr_scale_factor = get_total_scale_factor(expr)
return expr_scale_factor * Mul.fromiter(
(1 / get_total_scale_factor(u) * u)**p
for u, p in zip(target_units, depmat))
def as_explicit(self):
return Add.fromiter([arg.as_explicit() for arg in self.args])
def do_convert(self, expr, indices):
if isinstance(expr, ArrayTensorProduct):
cumul = list(accumulate([0] + [get_rank(arg) for arg in expr.args]))
indices_grp = [indices[cumul[i]:cumul[i+1]] for i in range(len(expr.args))]
return Mul.fromiter(self.do_convert(arg, ind) for arg, ind in zip(expr.args, indices_grp))
if isinstance(expr, ArrayContraction):
new_indices = [None for i in range(get_rank(expr.expr))]
limits = []
bottom_shape = get_shape(expr.expr)
for contraction_index_grp in expr.contraction_indices:
d = Dummy(f"d{self.count_dummies}")
self.count_dummies += 1
dim = bottom_shape[contraction_index_grp[0]]
limits.append((d, 0, dim-1))
for i in contraction_index_grp:
new_indices[i] = d
j = 0
for i in range(len(new_indices)):
if new_indices[i] is None:
new_indices[i] = indices[j]
j += 1
newexpr = self.do_convert(expr.expr, new_indices)
return Sum(newexpr, *limits)
if isinstance(expr, ArrayDiagonal):
new_indices = [None for i in range(get_rank(expr.expr))]
ind_pos = expr._push_indices_down(expr.diagonal_indices, list(range(len(indices))), get_rank(expr))
for i, index in zip(ind_pos, indices):
if isinstance(i, collections.abc.Iterable):
for j in i:
new_indices[j] = index
else:
new_indices[i] = index
newexpr = self.do_convert(expr.expr, new_indices)
return newexpr
if isinstance(expr, PermuteDims):
permuted_indices = _apply_permutation_to_list(expr.permutation, indices)
return self.do_convert(expr.expr, permuted_indices)
if isinstance(expr, ArrayAdd):
return Add.fromiter(self.do_convert(arg, indices) for arg in expr.args)
if isinstance(expr, _ArrayExpr):
return expr.__getitem__(tuple(indices))
if isinstance(expr, ArrayElementwiseApplyFunc):
return expr.function(self.do_convert(expr.expr, indices))
if isinstance(expr, Reshape):
shape_up = expr.shape
shape_down = get_shape(expr.expr)
cumul = list(accumulate([1] + list(reversed(shape_up)), operator.mul))
one_index = Add.fromiter(i*s for i, s in zip(reversed(indices), cumul))
dest_indices = [None for _ in shape_down]
c = 1
for i, e in enumerate(reversed(shape_down)):
if c == 1:
if i == len(shape_down) - 1:
dest_indices[i] = one_index
else:
dest_indices[i] = one_index % e
elif i == len(shape_down) - 1:
dest_indices[i] = one_index // c
else:
dest_indices[i] = one_index // c % e
c *= e
dest_indices.reverse()
return self.do_convert(expr.expr, dest_indices)
return _get_array_element_or_slice(expr, indices)
def convert_unit_to(expr,
target_units,
unit_system=kamodo_unit_system,
raise_errors=True):
"""
Same as sympy.convert_to but accepts equations and allows functions of units to pass
Convert ``expr`` to the same expression with all of its units and quantities
represented as factors of ``target_units``, whenever the dimension is compatible.
``target_units`` may be a single unit/quantity, or a collection of
units/quantities.
Examples
========
>>> from sympy.physics.units import speed_of_light, meter, gram, second, day
>>> from sympy.physics.units import mile, newton, kilogram, atomic_mass_constant
>>> from sympy.physics.units import kilometer, centimeter
>>> from sympy.physics.units import gravitational_constant, hbar
>>> from sympy.physics.units import convert_to
>>> convert_to(mile, kilometer)
25146*kilometer/15625
>>> convert_to(mile, kilometer).n()
1.609344*kilometer
>>> convert_to(speed_of_light, meter/second)
299792458*meter/second
>>> convert_to(day, second)
86400*second
>>> 3*newton
3*newton
>>> convert_to(3*newton, kilogram*meter/second**2)
3*kilogram*meter/second**2
>>> convert_to(atomic_mass_constant, gram)
1.660539060e-24*gram
Conversion to multiple units:
>>> convert_to(speed_of_light, [meter, second])
299792458*meter/second
>>> convert_to(3*newton, [centimeter, gram, second])
300000*centimeter*gram/second**2
Conversion to Planck units:
>>> from sympy.physics.units import gravitational_constant, hbar
>>> convert_to(atomic_mass_constant, [gravitational_constant, speed_of_light, hbar]).n()
7.62963085040767e-20*gravitational_constant**(-0.5)*hbar**0.5*speed_of_light**0.5
"""
from sympy.physics.units import UnitSystem
unit_system = UnitSystem.get_unit_system(unit_system)
if not isinstance(target_units, (Iterable, Tuple)):
target_units = [target_units]
if hasattr(expr, 'rhs'):
return Eq(convert_unit_to(expr.lhs, target_units, unit_system),
convert_unit_to(expr.rhs, target_units, unit_system))
# if type(type(expr)) is UndefinedFunction:
if is_function(expr):
# print('undefined input expr:{}'.format(expr))
return nsimplify(expr, rational=True)
if isinstance(expr, Add):
return Add.fromiter(
convert_unit_to(i, target_units, unit_system) for i in expr.args)
expr = sympify(expr)
if not isinstance(expr, Quantity) and expr.has(Quantity):
try:
expr = expr.replace(
lambda x: isinstance(x, Quantity),
lambda x: x.convert_to(target_units, unit_system))
except OSError:
raise OSError('problem converting {} to {}\n{}'.format(
expr, target_units, unit_system))
def get_total_scale_factor(expr):
if isinstance(expr, Mul):
return reduce(lambda x, y: x * y,
[get_total_scale_factor(i) for i in expr.args])
elif isinstance(expr, Pow):
return get_total_scale_factor(expr.base)**expr.exp
elif isinstance(expr, Quantity):
return unit_system.get_quantity_scale_factor(expr)
return expr
if expr == target_units:
return expr
depmat = _get_conversion_matrix_for_expr(expr, target_units, unit_system)
if depmat is None:
if raise_errors:
raise NameError('cannot convert {} to {} {}'.format(
expr, target_units, unit_system))
return nsimplify(expr, rational=True)
expr_scale_factor = get_total_scale_factor(expr)
result = expr_scale_factor * Mul.fromiter(
(1 / get_total_scale_factor(u) * u)**p
for u, p in zip(target_units, depmat))
return nsimplify(result, rational=True)
def divergence(vect, coord_sys=None, doit=True):
"""
Returns the divergence of a vector field computed wrt the base
scalars of the given coordinate system.
Parameters
==========
vector : Vector
The vector operand
coord_sys : CoordSys3D
The coordinate system to calculate the gradient in
Deprecated since version 1.1
doit : bool
If True, the result is returned after calling .doit() on
each component. Else, the returned expression contains
Derivative instances
Examples
========
>>> from sympy.vector import CoordSys3D, divergence
>>> R = CoordSys3D('R')
>>> v1 = R.x*R.y*R.z * (R.i+R.j+R.k)
>>> divergence(v1)
R.x*R.y + R.x*R.z + R.y*R.z
>>> v2 = 2*R.y*R.z*R.j
>>> divergence(v2)
2*R.z
"""
coord_sys = _get_coord_sys_from_expr(vect, coord_sys)
if len(coord_sys) == 0:
return S.Zero
elif len(coord_sys) == 1:
if isinstance(vect, (Cross, Curl, Gradient)):
return Divergence(vect)
# TODO: is case of many coord systems, this gets a random one:
coord_sys = next(iter(coord_sys))
i, j, k = coord_sys.base_vectors()
x, y, z = coord_sys.base_scalars()
h1, h2, h3 = coord_sys.lame_coefficients()
vx = _diff_conditional(vect.dot(i), x, h2, h3) \
/ (h1 * h2 * h3)
vy = _diff_conditional(vect.dot(j), y, h3, h1) \
/ (h1 * h2 * h3)
vz = _diff_conditional(vect.dot(k), z, h1, h2) \
/ (h1 * h2 * h3)
res = vx + vy + vz
if doit:
return res.doit()
return res
else:
if isinstance(vect, (Add, VectorAdd)):
return Add.fromiter(divergence(i, doit=doit) for i in vect.args)
elif isinstance(vect, (Mul, VectorMul)):
vector = [
i for i in vect.args
if isinstance(i, (Vector, Cross, Gradient))
][0]
scalar = Mul.fromiter(
i for i in vect.args
if not isinstance(i, (Vector, Cross, Gradient)))
res = Dot(
vector,
gradient(scalar)) + scalar * divergence(vector, doit=doit)
if doit:
return res.doit()
return res
elif isinstance(vect, (Cross, Curl, Gradient)):
return Divergence(vect)
else:
raise Divergence(vect)
def unify(expr, unit_registry, to_symbol=None, verbose=False):
"""adds unit conversion factors to composed functions"""
if verbose:
print('unify: to_symbol:', to_symbol)
if hasattr(expr, 'rhs'):
return Eq(
expr.lhs,
unify(expr.rhs, unit_registry, to_symbol=expr.lhs,
verbose=verbose))
if isinstance(expr, Add):
if verbose:
print('unify: Adding expression: {} -> {}'.format(
expr, get_expr_unit(to_symbol, unit_registry, verbose)))
return Add.fromiter([
unify(arg, unit_registry, to_symbol, verbose) for arg in expr.args
])
expr_unit = get_expr_unit(expr, unit_registry, verbose)
if verbose:
print('unify: {} unit {}'.format(expr, expr_unit))
print('unify: {} symbols {}'.format(expr, expr.free_symbols))
print('unify: {} symbols {}'.format(to_symbol, to_symbol.free_symbols))
try:
assert expr.free_symbols.issubset(to_symbol.free_symbols)
except:
raise NameError("{} arguments not in {}".format(
expr.free_symbols, to_symbol.free_symbols))
if is_function(expr):
if verbose:
print('unify: function expression: {}'.format(expr))
if to_symbol is not None:
if verbose:
print('\nunify: to_symbol args: {}'.format(to_symbol.args))
print('unify: to_symbol free symbols: {}'.format(
to_symbol.free_symbols))
print('unify: expr args: {}'.format(expr.args))
print('unify: expr free symbols: {}'.format(expr.free_symbols))
for k, v in unit_registry.items():
if isinstance(expr, type(k)):
if len(k.free_symbols) > 0:
if verbose:
print('unify: found matching {} -> {}'.format(
expr, k))
arg_units = get_arg_units(k, unit_registry)
if verbose:
print('unify: func units:', arg_units)
print('unify: {}->{}'.format(expr.args, k.args))
expr_units = {}
for arg, sym in zip(expr.args, k.args):
to_unit = arg_units.get(sym)
from_unit = get_expr_unit(arg, unit_registry)
if (from_unit is not None) and (to_unit
is not None):
expr_units[arg] = convert_unit_to(
arg * from_unit, to_unit,
kamodo_unit_system) / to_unit
expr = expr.subs(expr_units)
if verbose:
print('unify: replaced args', expr)
expr = unify_args(expr, unit_registry, to_symbol, verbose)
if (to_symbol is not None) & (expr_unit is not None):
to_unit = get_expr_unit(to_symbol, unit_registry, verbose)
if verbose:
print('unify: to_unit {}'.format(to_unit))
expr_dimensions = get_dimensions(expr_unit)
to_dimensions = get_dimensions(to_unit)
if expr_dimensions.compare(to_dimensions) == 0:
if verbose:
print('unify: {} [{}] -> to_symbol: {}[{}]'.format(
expr, expr_unit, to_symbol, to_unit))
expr = convert_unit_to(expr * expr_unit, to_unit,
kamodo_unit_system) / to_unit
else:
if verbose:
print('unify: registry:')
for k, v in unit_registry.items():
print('unify:\t{} -> {}'.format(k, v))
print('compare:{}'.format(
expr_dimensions.compare(to_dimensions)))
error_msg = 'cannot convert {} [{}] {} to {}[{}] {}'.format(
expr, expr_unit, expr_dimensions, to_symbol, to_unit,
to_dimensions)
print(error_msg)
raise NameError(error_msg)
return expr
