Sympy: Simplifying Square Roots Of Squares

Sympy does not seem to be able to simplify an expression where the square root of a square of a variable is involved: In [28]: a = x**2 In [29]: b = a**(1/2) In [30]: b Out[30]:

Solution 1:

There are two problems with your example.

First sqrt(x**2)==x only for positive real numbers.

Second, for SymPy 1/2 and 0.5 are not the same things. The first is a Rational instance, the second is a float instance.

Finally, an example:

>>>x = Symbol('x', real=True)>>>(x**2)**(1./2)
∣x∣**1.0
>>>(x**2)**(S(1)/2) # S() is short for sympify()
∣x∣

sympify transforms python objects to more adequate SymPy objects.

Solution 2:

I assume you declare x as x = Symbol('x'). If you change it to x = Symbol('x', real=True) the expression should be simplified. You can find the reason why you have to explicitly state that your variable is real in the sympy bugtracker.

Solution 3:

The function you want is powdenest. If passed the force=True parameter, it will ignore assumptions

>>>powdenest(sqrt(x**2), force=True)
x