def _print_Assignment(self, expr):
lhs = expr.lhs
rhs = expr.rhs
# We special case assignments that take multiple lines
if isinstance(expr.rhs, C.Piecewise):
# Here we modify Piecewise so each expression is now
# an Assignment, and then continue on the print.
expressions = []
conditions = []
for (e, c) in rhs.args:
expressions.append(Assignment(lhs, e))
conditions.append(c)
temp = C.Piecewise(*zip(expressions, conditions))
return self._print(temp)
elif isinstance(lhs, C.MatrixSymbol):
# Here we form an Assignment for each element in the array,
# printing each one.
lines = []
for (i, j) in self._traverse_matrix_indices(lhs):
temp = Assignment(lhs[i, j], rhs[i, j])
code0 = self._print(temp)
lines.append(code0)
return "\n".join(lines)
elif self._settings["contract"] and (lhs.has(C.IndexedBase)
or rhs.has(C.IndexedBase)):
# Here we check if there is looping to be done, and if so
# print the required loops.
return self._doprint_loops(rhs, lhs)
else:
lhs_code = self._print(lhs)
rhs_code = self._print(rhs)
return self._get_statement("%s = %s" % (lhs_code, rhs_code))
def real_root(arg, n=None):
"""Return the real nth-root of arg if possible. If n is omitted then
all instances of (-n)**(1/odd) will be changed to -n**(1/odd); this
will only create a real root of a principle root -- the presence of
other factors may cause the result to not be real.
Examples
========
>>> from sympy import root, real_root, Rational
>>> from sympy.abc import x, n
>>> real_root(-8, 3)
-2
>>> root(-8, 3)
2*(-1)**(1/3)
>>> real_root(_)
-2
If one creates a non-principle root and applies real_root, the
result will not be real (so use with caution):
>>> root(-8, 3, 2)
-2*(-1)**(2/3)
>>> real_root(_)
-2*(-1)**(2/3)
See Also
========
sympy.polys.rootoftools.RootOf
sympy.core.power.integer_nthroot
root, sqrt
"""
if n is not None:
try:
n = as_int(n)
arg = sympify(arg)
if arg.is_positive or arg.is_negative:
rv = root(arg, n)
else:
raise ValueError
except ValueError:
return root(arg, n)*C.Piecewise(
(S.One, ~C.Equality(C.im(arg), 0)),
(C.Pow(S.NegativeOne, S.One/n)**(2*C.floor(n/2)), C.And(
C.Equality(n % 2, 1),
arg < 0)),
(S.One, True))
else:
rv = sympify(arg)
n1pow = Transform(lambda x: -(-x.base)**x.exp,
lambda x:
x.is_Pow and
x.base.is_negative and
x.exp.is_Rational and
x.exp.p == 1 and x.exp.q % 2)
return rv.xreplace(n1pow)
def _print_Assignment(self, expr):
# Copied from codeprinter, but remove special MatrixSymbol treatment
lhs = expr.lhs
rhs = expr.rhs
# We special case assignments that take multiple lines
if not self._settings["inline"] and isinstance(expr.rhs, C.Piecewise):
# Here we modify Piecewise so each expression is now
# an Assignment, and then continue on the print.
expressions = []
conditions = []
for (e, c) in rhs.args:
expressions.append(Assignment(lhs, e))
conditions.append(c)
temp = C.Piecewise(*zip(expressions, conditions))
return self._print(temp)
if self._settings["contract"] and (lhs.has(C.IndexedBase)
or rhs.has(C.IndexedBase)):
# Here we check if there is looping to be done, and if so
# print the required loops.
return self._doprint_loops(rhs, lhs)
else:
lhs_code = self._print(lhs)
rhs_code = self._print(rhs)
return self._get_statement("%s = %s" % (lhs_code, rhs_code))
