Hello Sylvian, It seems `solve` is unable to handle this. However, you can try using the `solve_poly_system` function in your case.
`In []: result = solve_poly_system(system, unknowns)` This returns a NoneType result which is indicative of the system being inconsistent. I think we need to improve upon this in the codebase. Thanks for pointing it out. -------------------- Kshitij Saraogi On Wed, Mar 16, 2016 at 8:14 PM Sylvain Meunier <[email protected]> wrote: > Hello, > > I'm trying to prove the following system has no solution using sympy (one > of my first attempt to use sympy) : > > a_1 = Symbol('a_1') > a_2 = Symbol('a_2') > a_3 = Symbol('a_3') > a_4 = Symbol('a_4') > b_1 = Symbol('b_1') > b_2 = Symbol('b_2') > b_3 = Symbol('b_3') > b_4 = Symbol('b_4') > > system = [ > a_1*b_2 - a_2*b_1 - 1, > a_1*b_3 - a_3*b_1, > a_1*b_4 - a_4*b_1, > a_2*b_3 - a_3*b_2, > a_2*b_4 - a_4*b_2, > a_3*b_4 - a_4*b_3 - 1 > ] > > unknowns = [ > a_1, a_2, a_3, a_4, b_1, b_2, b_3, b_4 > ] > > result = solve(system, unknowns) > > I expect result would be an empty dictionary but an exception is raised : > > Traceback (most recent call last): > File "D:\Sandbox\galgebra\tests\test_chapter2.py", line 162, in test > R = solve(system, unknowns) > File > "D:\Tools\WinPython-2.7\python-2.7.10.amd64\lib\site-packages\sympy\solvers\solvers.py", > line 911, in solve > solution = _solve_system(f, symbols, **flags) > File > "D:\Tools\WinPython-2.7\python-2.7.10.amd64\lib\site-packages\sympy\solvers\solvers.py", > line 1522, in _solve_system > raise NotImplementedError('no valid subset found') > NotImplementedError: no valid subset found > > Best regards > > Sylvain > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/sympy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/3af4090c-6e34-455a-afc0-7e11bf39c172%40googlegroups.com > <https://groups.google.com/d/msgid/sympy/3af4090c-6e34-455a-afc0-7e11bf39c172%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAAOtw_CWevxY%2BD5J1oLBRK3hR38tpf%2BV7q7pSv-7Krh6y3gndA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
