$\operatorname{d}f$ : total differential of $f$
$\operatorname{d}f(x,y,\cdots)=\frac{\partial f}{\partial x}\operatorname{d} x+\frac{\partial f}{\partial y}\operatorname{d}y+\cdots$
from ISO 80000-2 https://people.engr.ncsu.edu/jwilson/files/mathsigns.pdf#page=23
아무튼 그래서 '''total differential''' of $u:$
$du=\frac{\partial u}{\partial x}dx+\frac{\partial u}{\partial y}dy$
'''principal part in the change in $u$'''로 불리기도 한다고.
그리고 [[미분연산자,differentiation_operator]] 얘기도 나오는데,
$\frac{du}{dt}=\frac{\partial u}{\partial x}\frac{dx}{dt}+\frac{\partial u}{\partial y}\frac{dy}{dt}$
그래서 이변수연속함수의 미분연산자는 이렇게된다??
$\frac{d\spadesuit}{dt}=\frac{\partial \spadesuit}{\partial x}\frac{dx}{dt}+\frac{\partial \spadesuit}{\partial y}\frac{dy}{dt}$
#noindex
''Moved to [[VG:전미분,total_differential]]''
MKL [[전미분,total_derivative]]
http://www.math.odu.edu/~jhh/Volume-1.PDF p159-160
Up: [[미분,differential]] [[VG:편미분,partial_derivative]]
Compare: [[전미분,total_derivative]] (MERGE?)
[[https://terms.naver.com/entry.naver?docId=1139534&cid=40942&categoryId=32220 두산백과: 전미분 total differential]]
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