Terminology

English Chinese Notes
minuend − subtrahend = difference 被减数 - 减数 = 差
arithmetic progression (AP) / arithmetic sequence 等差数列
geometric progression (GP) / geometric sequence 等比数列
derivative 导数
turning point := at which the derivative changes sign 极值点 := 导数正负分界点(导数为0且变号) $f'=0$ && $f'(x-\delta) \cdot f'(x+\delta)<0$==单调性发生变化(但$x_0$处不一定可导)
stationary point / critical point, of a differentiable function := at which the derivative/slope is 0 可微函数 的 驻点 := 导数为0的点 $f'=0$,$x_0$可导是前提. 极值点+可导=驻点
saddle point (stationary points that are neither local maxima nor minima) 鞍点 (既不是最大值,也不是最小值的驻点)(导数为0,不变号) $f'=0$ && $f'(x-\delta) \cdot f'(x+\delta)>0$
inflection [point] == flex 拐点/反曲点,(凹凸分界点) $f''=0$ && $f''(x-\delta) \cdot f''(x+\delta)<0$ == 曲率变号
concave == convex upward 凹函数(头向上,两腿向下) $f''>0$
convex == concave upward 凸函数(头向下,两腿向上) $f''<0$

saddle point 鞍点:

秃子看头,凹看腿: (//秃 = 凸)

Linear Algebra

《Introduction to Applied Linear Algebra Vectors, Matrices, and Least Squares》,目前作为 Stanford 的 EE103 和 UCLA 的 EE133A 教材所使用。 <473页斯坦福和UCLA的线性代数教科书公开,还有配套PPT下载!> via Python数据科学.

Math is fun

ref: