目录
激活函数
Logistic
Softmax
Relu
Tanh
损失函数
0-1损失函数
平方损失函数
绝对值损失函数
对数损失函数
代价函数
均方误差
均方根误差
平均绝对值误差
交叉熵误差
激活函数
Logistic
二分类的sigmoid函数,如果叠加实现多分类,分类结果不是互斥的。比如某个结果可能既是苹果,又是水果
![](https://img-blog.csdnimg.cn/20200822210228833.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzdGN6aG5nMjAxMg==,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/2020082221035136.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzdGN6aG5nMjAxMg==,size_16,color_FFFFFF,t_70)
Softmax
多分类simoid函数,分类结果是互斥的。
Relu
![](https://img-blog.csdnimg.cn/20200822210544247.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzdGN6aG5nMjAxMg==,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20200822211522192.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzdGN6aG5nMjAxMg==,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/2020082221073418.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzdGN6aG5nMjAxMg==,size_16,color_FFFFFF,t_70)
Tanh
![](https://img-blog.csdnimg.cn/2020082221045764.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzdGN6aG5nMjAxMg==,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20200822210621705.png)
损失函数
0-1损失函数
![](https://img-blog.csdnimg.cn/20200822125647172.png)
平方损失函数
![](https://img-blog.csdnimg.cn/20200822130054242.png)
绝对值损失函数
![](https://img-blog.csdnimg.cn/20200822130138286.png)
对数损失函数
![](https://img-blog.csdnimg.cn/20200822130506820.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzdGN6aG5nMjAxMg==,size_16,color_FFFFFF,t_70)
代价函数
均方误差
![](https://img-blog.csdnimg.cn/20200822130605841.png)
均方根误差
![](https://img-blog.csdnimg.cn/20200822130632339.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzdGN6aG5nMjAxMg==,size_16,color_FFFFFF,t_70)
平均绝对值误差
![](https://img-blog.csdnimg.cn/20200822130727890.png)
交叉熵误差
![](https://img-blog.csdnimg.cn/20200822130751756.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VzdGN6aG5nMjAxMg==,size_16,color_FFFFFF,t_70)