工具
http://www.jihehuaban.com.cn/ 几何画板
https://www.geogebra.org/
https://www.geogebra.org/geometry
https://www.desmos.com/calculator
http://www.wolfram.com/
视频
http://www.3blue1brown.com/
http://www.numberphile.com/
做题
https://brilliant.org/
https://projecteuler.net/
https://artofproblemsolving.com/
科学计算
https://www.juliabox.com/ julia语言
https://octave-online.net/ gnu matlab 实现
https://matlab.mathworks.com/ 收费的matlab online
http://bigsec.net/b52/scipydoc/index.html python
https://processing.org/ processing
