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By : Vivek Jikar
Date : November 21 2020, 07:31 AM
it fixes the issue The relevant issue is https://github.com/sympy/sympy/issues/5904.
When evaluate=False, the args property is not sorted: code :
``````>>> a = sympify('x**2 + 1', evaluate=False)
>>> b = sympify('x**2 + 1')
>>> a == b
False
>>> a.args
(x**2, 1)
>>> b.args
(1, x**2)
``````
``````>>> a._sorted_args
[1, x**2]
>>> b._sorted_args
[1, x**2]
`````` ## Sympy function evaluation

By : Christopher Kroll
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further I may be wrong, but I don't think you can make it yell that way, because that's a scientific library so it is made for supporting imaginary numbers, but you can change it a bit:
code :
``````x=Symbol('x', real=True)
v = sqrt(1-x).subs(x, 9).evalf()

if not v.is_real:
raise ValueError, "math domain error"
``````
``````def assert_real(v):
if not v.is_real:
raise ValueError, "math domain error"
return v
``````
``````x = Symbol('x', real=True)
v = assert_real(sqrt(1-x).subs(x, 9).evalf())
`````` ## Sympy - Comparing expressions

By : Todd Scopio
Date : March 29 2020, 07:55 AM
code :
``````>>> from sympy import simplify
>>> from sympy.abc import x,y
>>> vers1 = (x+y)**2
>>> vers2 = x**2 + 2*x*y + y**2
>>> simplify(vers1-vers2) == 0
True
>>> simplify(vers1+vers2) == 0
False
`````` ## Pickle and evaluation of sympy expressions

By : Mx Dep
Date : March 29 2020, 07:55 AM
Any of those help The comment by user2357112 answers the question.
code :
``````>>>with evaluate(False) : x = atan(sqrt(3))
>>>x
atan(sqrt(3))
>>> y = pickle.dumps(x)
>>> with evaluate(False) : z = pickle.loads(y)
>>> z
atan(sqrt(3))
`````` ## Sympy - comparing equivalent expressions with equal (=) sign

By : user1343413
Date : March 29 2020, 07:55 AM
I wish this help you What makes these equations equivalent is that they have the same solution set or that they are the same when solved for x. Have sympy solve them and compare the solutions:
code :
``````from sympy import *
x, y = symbols('x y')

a = Eq(2*x,6)
b = Eq(x,3)
print(solve(a) == solve(b)) #True
``````
``````a = Eq(x*(y+1),6)
b = Eq(2*x*y + 2*x, 12)
print(solve(a)) # [{x: 6/(y + 1)}]
print(solve(b)) # [{x: 6/(y + 1)}]
print(solve(a) == solve(b)) # True
`````` ## Avoid evaluation of multiplication by 1 in sympy
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