SymPyで不等式を解く

solve_univariate_inequality()を使うのが良さそう。

環境

  • SymPy 1.11

例

import sympy as sp

x = sp.Symbol('x', nonnegative=True)
expr = x ** 2 + 4 * x + 4
threshold = 9

sp.solve_univariate_inequality(expr >= threshold, x, relational=False, continuous=True)

> (−∞,−5]∪[1,∞)

domainを使うことで、正数範囲のみを指定できたりする。

import sympy as sp

x = sp.Symbol('x', nonnegative=True)
expr = x ** 2 + 4 * x + 4
threshold = 9
domain = sp.Interval(0, sp.S.Infinity)

sp.solve_univariate_inequality(expr >= threshold, x, relational=False, continuous=True, domain=domain)

> [1,∞)

参考