擅长:python、mysql、java
<p>可以说,避免这个问题的最简洁的方法是告诉<code>sympify</code>对选定的符号/字符串使用自定义定义,例如:</p>
<pre><code>from sympy.abc import *
from sympy import sin, pi, Lambda, sympify
sin_degree = Lambda(x, sin(x*pi/180))
degree_trigs = {"sin": sin_degree}
expr_string = "sin(a) + sin(b**d + exp(c))"
expr = sympify(expr_string, locals=degree_trigs)
print(expr)
</code></pre>
<p>这将返回:</p>
<pre><code>sin(pi*a/180) + sin(pi*(b**d/180 + exp(c)/180))
</code></pre>