Why wouldn't the input just be the inequality object itself?
Aaron Meurer
On Sun, May 10, 2015 at 7:23 AM, Amit Saha <amitsaha...@gmail.com> wrote:
> Hi all,
>
> I was exploring the inequality solvers [1] and it seemed to me that
> for someone exploring inequality solving with sympy, a helper method
> which would just allow the user to feed in the expression and the
> relational operator would be useful:
>
> from sympy import Symbol, solve_poly_inequality,
> solve_rational_inequalities, solve_univariate_inequality
> def isolve(str_expr, rel):
> x = Symbol('x')
> expr = sympify(str_expr)
> if expr.is_polynomial():
> # create a Poly() object
> 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:
> # solve_univariate_uninequality() function expects
> # the expressesion in the form "expr" "rel" 0
> expr = sympify(str_expr + rel + '0')
> return solve_univariate_inequality(expr , x, relational=False)
>
> # polynomial
> print(isolve('x+2', '<'))
> # rational function
> print(isolve('(x-1)/(x+2)', '>'))
> # non-polynomial, non-rational
> print(isolve('sin(x)-1', '<'))
>
>
> Output:
>
> [(-oo, -2)]
> (-oo, -2) U (1, oo)
> (-oo, pi/2) U (pi/2, oo)
>
>
> [1] http://docs.sympy.org/dev/modules/solvers/inequalities.html
>
> What do you all think of this? Is there a better way to do this? If we
> have such a method, the user could just call isolve() function, and if
> needed learn more about each individual function.
>
> Best,
> Amit.
>
>
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