def _parallel_dict_from_expr_if_gens(exprs, opt):
"""Transform expressions into a multinomial form given generators. """
k, indices = len(opt.gens), {}
for i, g in enumerate(opt.gens):
indices[g] = i
polys = []
for expr in exprs:
poly = {}
if expr.is_Equality:
expr = expr.lhs - expr.rhs
for term in Add.make_args(expr):
coeff, monom = [], [0] * k
for factor in Mul.make_args(term):
if not _not_a_coeff(factor) and factor.is_Number:
coeff.append(factor)
else:
try:
base, exp = decompose_power(factor)
if exp < 0:
exp, base = -exp, Pow(base, -S.One)
monom[indices[base]] += exp
except KeyError:
if not factor.free_symbols.intersection(opt.gens):
coeff.append(factor)
else:
raise PolynomialError(
"%s contains an element of the generators set"
% factor)
monom = tuple(monom)
if monom in poly:
poly[monom] += Mul(*coeff)
else:
poly[monom] = Mul(*coeff)
polys.append(poly)
return polys, opt.gens
def test_decompose_power():
assert decompose_power(x) == (x, 1)
assert decompose_power(x**2) == (x, 2)
assert decompose_power(x**(2 * y)) == (x**y, 2)
assert decompose_power(x**(2 * y / 3)) == (x**(y / 3), 2)
def test_decompose_power():
assert decompose_power(x) == (x, 1)
assert decompose_power(x**2) == (x, 2)
assert decompose_power(x**(2*y)) == (x**y, 2)
assert decompose_power(x**(2*y/3)) == (x**(y/3), 2)
def _parallel_dict_from_expr_no_gens(exprs, opt):
"""Transform expressions into a multinomial form and figure out generators. """
if opt.domain is not None:
def _is_coeff(factor):
return factor in opt.domain
elif opt.extension is True:
def _is_coeff(factor):
return factor.is_algebraic
elif opt.greedy is not False:
def _is_coeff(factor):
return False
else:
def _is_coeff(factor):
return factor.is_number
gens, reprs = set(), []
for expr in exprs:
terms = []
if expr.is_Equality:
expr = expr.lhs - expr.rhs
for term in Add.make_args(expr):
coeff, elements = [], defaultdict(int)
for factor in Mul.make_args(term):
if not _not_a_coeff(factor) and (factor.is_Number
or _is_coeff(factor)):
coeff.append(factor)
else:
base, exp = decompose_power(factor)
if exp < 0:
exp, base = -exp, Pow(base, -S.One)
elements[base] += exp
gens.add(base)
terms.append((coeff, elements))
reprs.append(terms)
if not gens:
if len(exprs) == 1:
arg = exprs[0]
else:
arg = (exprs, )
raise GeneratorsNeeded("specify generators to give %s a meaning" % arg)
gens = _sort_gens(gens, opt=opt)
k, indices = len(gens), {}
for i, g in enumerate(gens):
indices[g] = i
polys = []
for terms in reprs:
poly = {}
for coeff, term in terms:
monom = [0] * k
for base, exp in term.items():
monom[indices[base]] = exp
monom = tuple(monom)
if monom in poly:
poly[monom] += Mul(*coeff)
else:
poly[monom] = Mul(*coeff)
polys.append(poly)
return polys, tuple(gens)