如何计算π幂2？

Question

equations = [
    Eq(N_bRd, X_c * f_y * A * gamma_M1),
    Eq(L_c, L * beta),
    Eq(N_cr, (pi) ** 2 * E_E * i / (beta * L) ** 2),
    Eq(lamda, sqrt(N_bRd / N_cr)),
]
results = solve(equations)
# results = solve(equations, [m_A,m_D,theta_c,theta_b,delta])
results

我在sympy上遇到了以下错误 符号代数：

pi doesn't seem to be an algebraic element

当我把π改成3.14的时候，它工作得很好。你知道吗

Answer 1

公共mathematical constants在mpmath模块（一个sympy依赖项）中定义：

>>> from mpmath import mp
>>> mp.pi
<pi: 3.14159~>

>>> mp.pi**2
mpf('9.869604401089358')

从sympydocs开始：

These constants are implemented as lazy objects that can evaluate to any precision. Whenever the objects are used as function arguments or as operands in arithmetic operations, they automagically evaluate to the current working precision.