What version of SymPy is this? On master I get
In [1]: x = symbols('x', real=True)
In [2]: f = Lambda(x, 2*sqrt(x)*sqrt(x**3 - x**2 + 1) + 2*x**3 - x**2
+ x*sqrt(x**3 - x**2 + 1) + 2*x**1.5 + 2*x**2.5*sqrt(x**3 - x**2 + 1)
- 3*x**2.5 - 4*x**3.5*sqrt(x**3 - x**2 + 1) - 2*x**3.5 + 5*x**4.5 -
3*x**5.5 - 1)
In [3]: solve(f(x), x)
Out[3]: [0.149910458676117, 1.0]
(note that it takes a while)
Aaron Meurer
On Tue, May 19, 2015 at 6:29 AM, Arnaud Usciati <[email protected]> wrote:
> Hello,
>
> I tried to find the roots of : 2*sqrt(x)*sqrt(x**3 - x**2 + 1) + 2*x**3 -
> x**2 + x*sqrt(x**3 - x**2 + 1) + 2*x**1.5 + 2*x**2.5*sqrt(x**3 - x**2 + 1) -
> 3*x**2.5 - 4*x**3.5*sqrt(x**3 - x**2 + 1) - 2*x**3.5 + 5*x**4.5 - 3*x**5.5 -
> 1 = 0.
>
> x = symbols('x', real=True)
> f = Lambda(x, 2*sqrt(x)*sqrt(x**3 - x**2 + 1) + 2*x**3 - x**2 + x*sqrt(x**3
> - x**2 + 1) + 2*x**1.5 + 2*x**2.5*sqrt(x**3 - x**2 + 1) - 3*x**2.5 -
> 4*x**3.5*sqrt(x**3 - x**2 + 1) - 2*x**3.5 + 5*x**4.5 - 3*x**5.5 - 1)
>
> Input : solve(f(x), x)
> Output : [0.149910458676117, 0.865324593883105, 1.00000000000000,
> 1.24896947842683, 2.56371129870321, 3.02429035798029]
>
> But only 0.149910458676117 and 1 are really roots :
> f(0.865324593883105) = 0.735269457206734
> f(1.24896947842683) = -4.09736628717860
> f(2.56371129870321) = -509.709822051607
> f(3.02429035798029) = -1361.51149028959
>
> Arnaud,
>
> Python 3.4.2 (v3.4.2:ab2c023a9432, Oct 6 2014, 22:15:05) [MSC v.1600 32 bit
> (Intel)] on win32
>
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