def create_expand_pow_optimization(limit):
""" Creates an instance of :class:`ReplaceOptim` for expanding ``Pow``.
The requirements for expansions are that the base needs to be a symbol
and the exponent needs to be an Integer (and be less than or equal to
``limit``).
Parameters
==========
limit : int
The highest power which is expanded into multiplication.
Examples
========
>>> from sympy import Symbol, sin
>>> from sympy.codegen.rewriting import create_expand_pow_optimization
>>> x = Symbol('x')
>>> expand_opt = create_expand_pow_optimization(3)
>>> expand_opt(x**5 + x**3)
x**5 + x*x*x
>>> expand_opt(x**5 + x**3 + sin(x)**3)
x**5 + sin(x)**3 + x*x*x
"""
return ReplaceOptim(
lambda e: e.is_Pow and e.base.is_symbol and e.exp.is_Integer and abs(
e.exp) <= limit, lambda p:
(UnevaluatedExpr(Mul(*([p.base] * +p.exp), evaluate=False))
if p.exp > 0 else 1 / UnevaluatedExpr(
Mul(*([p.base] * -p.exp), evaluate=False))))
def test_UnevaluatedExpr():
p, q, r = symbols("p q r", real=True)
q_r = UnevaluatedExpr(q + r)
expr = abs(exp(p + q_r))
assert fcode(expr, source_format="free") == "exp(p + (q + r))"
x, y, z = symbols("x y z")
y_z = UnevaluatedExpr(y + z)
expr2 = abs(exp(x + y_z))
assert fcode(expr2, human=False)[2].lstrip() == "exp(re(x) + re(y + z))"
assert fcode(expr2, user_functions={
"re": "realpart"
}).lstrip() == "exp(realpart(x) + realpart(y + z))"
def ccode(eq) -> str:
"""Transforms a sympy expression into C99 code.
Applies C99 optimizations (`sympy.codegen.rewriting.optims_c99`).
Expands `pow(x; 2)` into `x*x` and `pow(x, 3)` into `x*x*x` for performance.
Args:
eq (sympy expression): expression to convert.
Returns:
a string representing the C code.
"""
# If the rhs is a int or float (v = 0.0), cast it to a symbol to avoid numerical errors.
if isinstance(eq, (float)):
eq = sp.Symbol(str(float(eq)))
elif isinstance(eq, (int)):
eq = sp.Symbol(str(int(eq)))
# Optimize for C99
try:
eq = optimize(eq, optims_c99)
except:
logger = logging.getLogger(__name__)
logger.exception(str(eq))
sys.exit(1)
# Explicitly expand the use of pow(x, 2)
pow2 = ReplaceOptim(
lambda p: p.is_Pow and p.exp == 2,
lambda p: UnevaluatedExpr(Mul(p.base, p.base, evaluate=False))
)
eq = pow2(eq)
# Explicitly expand the use of pow(x, 3)
pow3 = ReplaceOptim(
lambda p: p.is_Pow and p.exp == 3,
lambda p: UnevaluatedExpr(Mul(Mul(p.base, p.base, evaluate=False), p.base, evaluate=False))
)
eq = pow3(eq)
# Get the equivalent C code
eq = sp.ccode(
eq,
)
# Remove the extralines of Piecewise
return " ".join(eq.replace('\n', ' ').split())
def test_own_module():
f = lambdify(x, sin(x), math)
assert f(0) == 0.0
p, q, r = symbols("p q r", real=True)
ae = abs(exp(p + UnevaluatedExpr(q + r)))
f = lambdify([p, q, r], [ae, ae], modules=math)
results = f(1.0, 1e18, -1e18)
refvals = [math.exp(1.0)] * 2
for res, ref in zip(results, refvals):
assert abs((res - ref) / ref) < 1e-15
def create_expand_pow_optimization(limit, *, base_req=lambda b: b.is_symbol):
""" Creates an instance of :class:`ReplaceOptim` for expanding ``Pow``.
Explanation
===========
The requirements for expansions are that the base needs to be a symbol
and the exponent needs to be an Integer (and be less than or equal to
``limit``).
Parameters
==========
limit : int
The highest power which is expanded into multiplication.
base_req : function returning bool
Requirement on base for expansion to happen, default is to return
the ``is_symbol`` attribute of the base.
Examples
========
>>> from sympy import Symbol, sin
>>> from sympy.codegen.rewriting import create_expand_pow_optimization
>>> x = Symbol('x')
>>> expand_opt = create_expand_pow_optimization(3)
>>> expand_opt(x**5 + x**3)
x**5 + x*x*x
>>> expand_opt(x**5 + x**3 + sin(x)**3)
x**5 + sin(x)**3 + x*x*x
>>> opt2 = create_expand_pow_optimization(3 , base_req=lambda b: not b.is_Function)
>>> opt2((x+1)**2 + sin(x)**2)
sin(x)**2 + (x + 1)*(x + 1)
"""
return ReplaceOptim(
lambda e: e.is_Pow and base_req(e.base) and e.exp.is_Integer and abs(e.exp) <= limit,
lambda p: (
UnevaluatedExpr(Mul(*([p.base]*+p.exp), evaluate=False)) if p.exp > 0 else
1/UnevaluatedExpr(Mul(*([p.base]*-p.exp), evaluate=False))
))
def test_UnevaluatedExpr():
a, b = symbols("a b")
expr1 = 2*UnevaluatedExpr(a+b)
assert str(expr1) == "2*(a + b)"
