'''

isolve.py

Single variable inequality solver

'''

from sympy import Symbol, sympify, SympifyError

from sympy import solve_poly_inequality, solve_rational_inequalities

from sympy import solve_univariate_inequality, Poly

from sympy.core.relational import Relational, Equality

def isolve(ineq_obj):

x = Symbol('x')

expr = ineq_obj.lhs

rel = ineq_obj.rel_op

if expr.is_polynomial():

p = Poly(expr, x)

return solve_poly_inequality(p, rel)

elif expr.is_rational_function():

p1, p2 = expr.as_numer_denom()

num = Poly(p1)

denom = Poly(p2)

return solve_rational_inequalities([[((num, denom), rel)]])

else:

return solve_univariate_inequality(ineq_obj , x, relational=False)

if __name__ == '__main__':

ineq = input('Enter the inequality to solve: ')

try:

ineq_obj = sympify(ineq)

except SympifyError:

print('Invalid inequality')

else:

# We check if the input expression is an inequality here

if isinstance(ineq_obj, Relational) and not isinstance(ineq_obj, Equality):

print(isolve(ineq_obj))

else:

print('Invalid inequality')