Content Optimization and Creation Tools: SEMrush
优点：输出在 (−1,1)，比 sigmoid 居中，对梯度更友好
。Line官方版本下载对此有专业解读
Reporting by Chance Townsend, Caitlin Welsh, Sam Haysom, Amanda Yeo, Shannon Connellan, Cecily Mauran, Mike Pearl, and Adam Rosenberg contributed to this article.
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