from sympy import *if __name__ == '__main__':# 函数表达式变量x, y = symbols('x y')# 二元函数表达式f = x ** 2 + 3 * x * y + y - 1# f关于x的偏导数,y是常量fx = diff(f, x)print(fx)# f关于y的偏导数,x是常量fy = diff(f, y)print(fy)result1 = fx.subs({x: 4, y: -5})print(result1)result2 = fy.subs([(x, 4), (y, -5)])print(result2)# 再来一例二元三角函数的偏导数# 求 f = y*sin(x*y)关于y的偏导数，x是常量print(diff(y * sin(x * y), y))
输出：
2*x + 3*y
3*x + 1
-7
13
x*y*cos(x*y) + sin(x*y)