Lagrange's Notation (prime notation)y′=f′(x), y″f_x(x,y), \ f_{xx}(x,y), \ f_{xy}(x,y)日本ではy'をワイダッシュ,f'(x)をエフダッシュエクスと読むことが多いですが,英語では"y prime","f prime of x"と読むのでprime notationともいいます.2行目は偏微分の記法で,こちらはsubscript(添え字)を使うのでsubscript notationのひとつになります.
Leibniz's Notation (differential notation)\frac{dy}{dx}=\frac{d}{dx}f(x), \quad \frac{d}{dx}\left( \frac{dy}{dx}\right)=\frac{d^2y}{dx^2}\frac{\partial f}{\partial x}, \ \frac{\partial^2 f}{\partial x^2}, \ \frac{\partial^2 f}{\partial x \partial y}\frac{dy}{dx}は"the derivative of y with respect to x"と読みますが,短く言う場合は,分数のように"dy over dx"とは読まず,単に"dy dx"と読みます.分数ではないのですが,置換積分のときに,\frac{dx}{dt}=g'(t)を形式的にdx=g'(t)dtとして分数のように扱うことで式変形が容易になっています.
偏微分の\frac{\partial f}{\partial x}は,"the partial derivative of f with respect to x"とか"the partial derivative of f in the x direction"と読みますが,"dee f dee x","del f del x","day f day x"などと短く言うことがあります.\partial単独では"curly dee","rounded dee"などと言います
以上はよく使われる記法ですが,他にも次のような記法があります.
Euler's Notation (D notation or operator notation)Dy=Df, \ D^2y=D^2f\ D_xf, \ D_{xx}f, \ D_{xy}fこの表記は多変数の関数でよく使われます.例えばD_xfは"D sub x of f"と読みます.
Newton's Notation (Dot Notation)\dot{y}, \ \ddot{y}この表記はkinematics(運動学)でよく使われ,時刻tにおける位置をyとするとき,velocity(速度)を\dot{y},acceleration(加速度)を\ddot{y}で表します.
[Lagrange's Notation, Leibniz's Notation 問題]
Let x be the number of thousands of units of an item produced. The revenue for
selling x units is r(x) = 4 \sqrt x and the cost of producing x units is c(x) = 2x^2
a) The profit p(x)=r(x)-c(x). Write an expression for p(x).
b) Find \frac{dp}{dx} and \frac{d^2p}{dx^2}.
c) Hence find the number of units that should be produced in order to maximize
the profit.
(IB Mathematics Standard Level (Oxford University Press) exercise 7Y 5)
解答はこちら
[Reference]
IB Mathematics Standard Level (Oxford IB Diploma Programme 2012)
by Paul La Rondie, Ed Kem, Laurie Buchanan, Jim Fensom, Jill Stevens
Notation for differentiation
https://en.wikipedia.org/wiki/Notation_for_differentiation
The Notation of Differentiation
http://web.mit.edu/wwmath/calculus/differentiation/notation.html
∂
https://en.wikipedia.org/wiki/%E2%88%82
How do you pronounce (partial) derivatives?
https://math.stackexchange.com/questions/120504/how-do-you-pronounce-partial-derivatives
以上はよく使われる記法ですが,他にも次のような記法があります.
Euler's Notation (D notation or operator notation)Dy=Df, \ D^2y=D^2f\ D_xf, \ D_{xx}f, \ D_{xy}fこの表記は多変数の関数でよく使われます.例えばD_xfは"D sub x of f"と読みます.
Newton's Notation (Dot Notation)\dot{y}, \ \ddot{y}この表記はkinematics(運動学)でよく使われ,時刻tにおける位置をyとするとき,velocity(速度)を\dot{y},acceleration(加速度)を\ddot{y}で表します.
[Lagrange's Notation, Leibniz's Notation 問題]
Let x be the number of thousands of units of an item produced. The revenue for
selling x units is r(x) = 4 \sqrt x and the cost of producing x units is c(x) = 2x^2
a) The profit p(x)=r(x)-c(x). Write an expression for p(x).
b) Find \frac{dp}{dx} and \frac{d^2p}{dx^2}.
c) Hence find the number of units that should be produced in order to maximize
the profit.
(IB Mathematics Standard Level (Oxford University Press) exercise 7Y 5)
解答はこちら
[Reference]
IB Mathematics Standard Level (Oxford IB Diploma Programme 2012)
by Paul La Rondie, Ed Kem, Laurie Buchanan, Jim Fensom, Jill Stevens
Notation for differentiation
https://en.wikipedia.org/wiki/Notation_for_differentiation
The Notation of Differentiation
http://web.mit.edu/wwmath/calculus/differentiation/notation.html
∂
https://en.wikipedia.org/wiki/%E2%88%82
How do you pronounce (partial) derivatives?
https://math.stackexchange.com/questions/120504/how-do-you-pronounce-partial-derivatives
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