Solving an equation containing absolute value, with python 3

[Cesar Romani]

I'm trying to solve the following equation, with python 3.6.3 on Windows 7:

||x² - 1| - x| = x

I did

from sympy import *

x = Symbol('x', real=True)

solve(abs((abs(x**2-1)-x))-x)

but I get the following error:

--------------------

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "C:\Python36-32\lib\site-packages\sympy\solvers\solvers.py", line 1065, in solve

solution = _solve(f[0], *symbols, **flags)

  File "C:\Python36-32\lib\site-packages\sympy\solvers\solvers.py", line 1366, in _solve

candidates = _solve(piecewise_fold(expr), symbol, **flags)

  File "C:\Python36-32\lib\site-packages\sympy\solvers\solvers.py", line 1634, in _solve

raise NotImplementedError('\n'.join([msg, not_impl_msg % f]))

NotImplementedError: multiple generators [x, Abs(-x**2 + x + 1)]

No algorithms are implemented to solve equation -x + Abs(-x**2 + x + 1)

--------------------

I updated SymPy to the latest version, 1.4, but I get the same error.

But, with python 2.7.14 I get answers, namely [1, -1+sqrt(2), 1+sqrt(2)].

Am I missing something with Python 3?

Many thanks in advance,

-- 

Cesar

[Aaron Meurer]

Python 2 and Python 3 use separate installations, so it's likely that
you have different sympy versions installed. You can check which
version is being used with

import sympy
sympy.__version__

I checked and this did indeed used to work in an older version (I
tested 1.1) but doesn't work in the latest version or the git master.
Can you open an issue at https://github.com/sympy/sympy/issues for
this?

Aaron Meurer

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[Steve F]

Hi,

  Here is a simple problem that worked for me:

from sympy import *

x = Symbol('x', real=True)

solve((abs(2*x-4))-14)

[Chris Smith]

This is reported as a issue 17650.