如何理解傅里叶变换？

https://www.zhihu.com/question/19714540

 

https://www.cnblogs.com/tenderwx/p/5245859.html

 

http://blog.csdn.net/abcjennifer/article/details/7622228

卷积
https://www.zhihu.com/question/22298352

 

https://zhuanlan.zhihu.com/p/19759362

 

https://www.cnblogs.com/bithuaning/p/6924978.html