首先先回顾一下高中的通过定义求导
# 1.单变量求导
def f(x):
return 3. * x ** 2 + 2. * x - 1
def approximate_derivative(f, x, eps=1e-3):
return (f(x + eps) - f(x - eps)) / (2. * eps)
print(approximate_derivative(f, 1.)) # 7.999999
# 2.求偏导
def g(x1, x2):
return (x1 + 5) * (x2 ** 2)
def approximate_gradient(g, x