Hi all,
I am new to sympy (and to symbolic computations...) and I meet a problem
for solving (possibly difficult) inequalities depending upon on real
symbol
(I have used k = symbols('k',real=True,positive=True)).
First I build a set of (5) inequalities, stored in a list L and I want to
find
for which subset (of real numbers) they are all true. Substition for a
given value
of the symbol k works, for instance :
for elem in L:
print(elem.subs(k,Rational(9,4)))
outputs five True. But solving this way :
res = solve([k>2, k <= 3, L[0], L[1], L[2], L[3], L[4]], k)
leads to the following error:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.7/site-packages/sympy/solvers/solvers.py", line 691,
in solve
return reduce_inequalities(f, symbols=symbols)
File "/usr/lib/python2.7/site-packages/sympy/solvers/inequalities.py", line
513, in reduce_inequalities
poly_reduced.append(reduce_rational_inequalities([exprs], gen))
File "/usr/lib/python2.7/site-packages/sympy/solvers/inequalities.py", line
255, in reduce_rational_inequalities
result = solution.as_relational(gen)
File "/usr/lib/python2.7/site-packages/sympy/sets/sets.py", line 1212, in
as_relational
return Or(*[set.as_relational(symbol) for set in self.args])
AttributeError: 'Complement' object has no attribute 'as_relational'
>From these messages, at first glance, I guessed for something wrong with my
relationals L but
each element of L seems to have a good type:
>>> type(L[1])
<class 'sympy.core.relational.StrictGreaterThan'>
the same than what returns: type(k>2). So I am wondering if I have made
some mistake or if this is due to some limitations as my relations are
quite complicated :
>>> L[1]
4*(-k**6 + 2*k**4 + 4*k**2 + 12)/(k*(-k**8 + 2*k**6 + 4*k**4 + 16*k**2 -
8)) > (k**8 - 4*k**6 + 16)/(k*(k**8 - 2*k**6 - 4*k**4 - 16*k**2 + 8))
Thanks for any help or advice
Bruno
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