实际运用例子:
https://zhuanlan.zhihu.com/p/35709485
pytorch CrossEntropyLoss,参考博客如下:
https://mathpretty.com/12068.html
https://blog.csdn.net/wyyang2/article/details/109218251?utm_medium=distribute.pc_relevant.none-task-blog-title-2&spm=1001.2101.3001.4242