幾個重要數學讀法
(C是一個實數) x趨于C時(經常的情況是"趨于無窮大時"),f(x)的極限是L。 the limit of f of x, as x approaches c, is L ※ f(x) can be made to be as close to L as desired by making x sufficiently close to c. |
f'(x) 或:f一撇x,f(x) 的導(函)數,函數f(x)的一階導數(first derivative)。我們經常求某一函數的導函數在某一點的值。 ※ 導數所表示的是一個極限值,而不是兩個數量 dy、dx 的商。 f''(x):f兩撇x,f'(x) 的導(函)數,f(x)的二階導數(second derivative) ※ 二階導數是斜率變化快慢的反應,表征曲線的凸凹性。 |
,讀作:x的m次方的微分=m乘以x的m減1次方乘以dx。(dx中的意思是infinitesimal [ɪnfɪnɪˈtesɪm(ə)l] adj. 極小的) |
若z=f(x,y),那麼讀作"函數z對x的偏微分(the partial derivative of z with respect to x)",或讀作"偏捱副 偏捱克斯"; 因為這個符号是法國人發明的,一開始是叫round。 |
函數f(x)的不定積分 the indefinite integral of f(x) 函數f(x)在a,b的閉區間(即,[a, b])内的定積分 the definite integral of the function of x from a to b |
n元函數
一進制函數(function of one variable)的圖像y=f(x)在二維坐标裡是曲線; 二進制函數(function of two variables)的圖像z=f(x,y)在三維坐标裡是曲面; 三元函數(function of three variables)的圖像w=f(x,y,z)在四維坐标裡是立體; 隻不過因為現實空間是三維的,是以需要一點想像力來想像四維坐标,及坐标裡的立體。 |
極限
limit Thus for the limit of a function to exist as the independent variable approaches c , the left-hand and right-hand limits must be equal. if and only if ※ 如果函數f(x)在自變量x的變化過程中存在極限,即常數A,那麼我們可以說f(x)收斂到A,簡稱f(x)收斂(convergence);否則,稱f(x)發散(divergence)。 |
導數
Derivative The instantaneous rate of change of a function with respect to its variable. 函數随其變量的即時變化率 Derivative is the slope of the tangent line to a function graph, e.g. a curve, at a certain point. Also called differential coefficient ,fluxion 微商/倒數函數圖像(如曲線)某一點切線的斜率。 嚴格定義: 如果函數f(x)在(a,b)中每一點處都可導,則稱f(x)在(a,b)上可導,則可建立f(x)的導函數,簡稱導數,記為f'(x). |
微分
differentiation The process of computing a derivative is called differentiation 微分:計算導數的過程 |
導數與微分的計算
設 u = u(x),v = v(x)為可導函數,c 是常數,則有: |
偏導數/偏微商
partial derivative The derivative with respect to a single variable of a function of two or more variables, regarding other variables as constants. 偏導數/偏微商:多變量函數對其中一個變量的微商,其餘變量視作常數. |
二進制函數偏導數的幾何意義
過M0點作平面y=y0 / 過M0點作平面x=x0: |