Sigmoid函数求导

Sigmoid函数求导

flyfish

实现Python

import math
import numpy as np

#基础版本 只能是一个值
def basic_sigmoid(x):
    s = 1.0 / (1 + 1/ math.exp(x))
    return s
#numpy 版
def sigmoid(x):
    s = 1.0 / (1 + 1 / np.exp(x))
    return s

#求导
def sigmoid_derivative(x):
    s = 1.0 / (1 + 1 / np.exp(x))
    ds = s * (1 - s)
    return ds

#求导过程

x = np.array([1, 2, 3])
print ("basic_sigmoid(x) = ",basic_sigmoid(1))
print ("sigmoid(x) = ",sigmoid(x))
print ("sigmoid_derivative(x) = ",(sigmoid_derivative(x)))

输出结果
basic_sigmoid(x) = 0.7310585786300049
sigmoid(x) = [0.73105858 0.88079708 0.95257413]
sigmoid_derivative(x) = [0.19661193 0.10499359 0.04517666]

过程

来源