def pow_atom_common_terms(pair):
# print "pow_atom_common_terms: finding common terms of " + str(pair)
if Rule.is_a(pair[1], Const):
return []
if pair[0].base() != pair[1]:
return []
return [pair[1]]
def pow_common_terms(pair):
# print "pow_common_terms: finding common terms of " + str(pair)
if not Rule.all_equal([term.base() for term in pair]):
return []
if Rule.all_are([term.exponent() for term in pair], Var):
return []
if Rule.all_are([term.exponent() for term in pair], Const):
if Rule.all_are([term.exponent().value() for term in pair], int):
v1 = pair[0].exponent().value()
v2 = pair[1].exponent().value()
return [Power(pair[0].base(), Const(min(v1, v2)))]
common_in_exp = common_terms((pair[0].exponent(), pair[1].exponent()))
if len(common_in_exp) > 0:
if len(common_in_exp) > 1:
mults = Multiply(*common_in_exp)
else:
mults = common_in_exp[0]
return [Power(pair[0].base(), mults)]
return []
def distribute_op(matched):
new_args = copy(matched.args)
def distribute_modifying_args(term, addition):
new_args.remove(addition)
new_args.remove(term)
new_args.append(Add(*[Multiply(term, add_arg) for add_arg in addition.args]))
if len(matched.args) > 1 and Rule.is_a(matched.args[0], Add):
distribute_modifying_args(matched.args[1], matched.args[0])
else:
for idx in range(1, len(matched.args)):
current_arg = matched.args[idx]
if Rule.is_a(current_arg, Add):
distribute_modifying_args(matched.args[0], current_arg)
break
print "distributing: " + str(matched)
print "new args: " + str(new_args)
if len(new_args) == 1:
return new_args[0]
else:
return Multiply(*new_args)
def pull_pow_from_mult(power, mult):
new_args = []
for fact in mult.args:
if Rule.is_a(fact, Power) and fact.base() == power.base():
new_args.append(pull(power, fact))
else:
new_args.append(fact)
if len(new_args) == 0:
return Const(1)
elif len(new_args) == 1:
return new_args[0]
else:
return Multiply(*new_args)
def pull(factor, value):
if Rule.is_a(factor, Const):
#it's only possible to pull a constant out of a const or a multiplication
if Rule.is_a(value, Const) and float(value.value()) % float(factor.value()) == 0:
return Const(value.value() / factor.value())
elif Rule.is_a(value, Multiply):
return pull_factor_from_mult(factor, value)
elif Rule.is_a(factor, Var):
#a var can be pulled out of a var, a multiplication, or a power
if Rule.is_a(value, Var) and value == factor:
return Const(1)
elif Rule.is_a(value, Multiply):
return pull_factor_from_mult(factor, value)
elif Rule.is_a(value, Power):
return Power(value.base(), Add(value.exponent(), Const(-1)))
elif Rule.is_a(factor, Add):
#an addition can be pulled out of a multiplication or a power
if Rule.is_a(value, Multiply):
return pull_factor_from_mult(factor, value)
elif Rule.is_a(value, Power):
return Power(value.base(), Add(value.exponent(), Const(-1)))
elif Rule.is_a(factor, Power):
#a power can be pulled out of a multiply or a power
if Rule.is_a(value, Multiply):
return pull_pow_from_mult(factor, value)
elif Rule.is_a(value, Power):
return Power(value.base(), Add(value.exponent(), Multiply(Const(-1), factor.exponent())))
return value
def common_terms(pair):
# print "common_terms: finding common terms of " + str(pair)
if Rule.all_are(pair, Const):
return const_common_terms(pair)
if Rule.all_are(pair, Var):
if pair[0] == pair[1]:
return [pair[0]]
else:
return []
if Rule.all_are(pair, Atom):
return []
if Rule.all_are(pair, Multiply):
return mult_common_terms(pair)
if Rule.is_a(pair[0], Multiply) and Rule.is_a(pair[1], Atom):
return mult_atom_common_terms(pair)
if Rule.is_a(pair[0], Atom) and Rule.is_a(pair[1], Multiply):
return mult_atom_common_terms((pair[1], pair[0]))
if Rule.all_are(pair, Power):
return pow_common_terms(pair)
if Rule.is_a(pair[0], Power) and Rule.is_a(pair[1], Atom):
return pow_atom_common_terms(pair)
if Rule.is_a(pair[0], Atom) and Rule.is_a(pair[1], Power):
return pow_atom_common_terms((pair[1], pair[0]))
if Rule.is_a(pair[0], Multiply) and Rule.is_a(pair[1], Power):
return mult_pow_common_terms(pair)
if Rule.is_a(pair[0], Power) and Rule.is_a(pair[1], Multiply):
return mult_pow_common_terms((pair[1], pair[0]))
return []
