Injective, Surjective, and Bijective
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Mathematics/Set Theory
InjectiveDefinition 1. A function f:XY is said to be injective or one-to-one if x1,x2X with f(x1)=f(x2), then x1=x2. SurjectiveDefinition 2. A function f:XY is said to be surjective or onto if yY, then there exists xX such that f(x)=y. In other words, f:XY is surjective f(X)=Y.Bijectiv..
Function
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Mathematics/Set Theory
FunctionDefinition 1. Let X,Y be sets. A function from X to Y is a relation f from X to Y satisfying (a) Dom(f) = X,(b) If (x,y)f and (x,z)f, then y=z.(x,y)f는 관습상 xfy가 아닌 y=f(x)라고 쓴다. 또한 X에서 Y로의 관계인 함수 ff:XY와 같이 표기한다. The Condition For Functions To Be EqualTheorem 1. Let f,g:XY be functions. The..
Partition
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Mathematics/Set Theory
PartitionDefinition 1. Let X be a nonempty set. A partition P of X is a set of nonempty subsets X such that (a) If A,BP and AB, then AB=(b) CPC=X.직관적으로 말하면, partiton은 집합 X를 겹치는 부분 없이 잘라놓은 집합이라고 할 수 있다. Equivalence Class, Quotient SetDefinition 2. Let R be an equivalence relation on a nonempty set X. F..
Indexed Families of Sets
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Mathematics/Set Theory
UnionDefinition 1. Let F be a family of sets. The union of the sets in F, denoted by AFA is the set of all elements that are in A for some AF. That is, AFA={xU|AF,xA}.IntersectionDefinition 2. Let F be a family of sets. The intersection of..
Divergence Theorem
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Mathematics/Calculus
Divergence TheoremTheorem 1. Let F be a vector field whose components have continuous first partial derivatives, and let S be a piecewise smooth oriented closed surface. The flux of F across S in the direction of the surface’s outward unit normal field n equals the triple integral of the divergence F over the region D enclosed by the..
Stokes's Theorem
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Mathematics/Calculus
Stokes's Theorem Theorem 1. Let S be a piecewise smooth oriented surface having a piecewise smooth boundary curve C. Let F=M,N,P be a vector field whose components have continuous first partial derivatives on an open region containing S. Then the circulation of F around C in the direction counterclockwise with respect to the surface’s un..
Surface Integral
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Mathematics/Calculus
Surface Integral of Scalar FunctionsLine integral이 임의의 곡선 위에서 함수를 적분하는 것이었다면, 이를 확장하여 임의의 surface 위에서 함수를 적분해보자. Scalar function G(x,y,z)와 smooth한 곡면 S가 있을 때, Suv 평면의 region R에서 좌표 공간으로의 transformation인 r(u,v)=f(u,v),g(u,v),h(u,v)에 의해 parametrization된다. S의 area를 구했을 때와 같이, R을 잘게 쪼갠 piece에 대응되는 S 위의 patch의 넓이를 Δσuv라고 하면 tangen..
Parametrization of Surfaces
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Mathematics/Calculus
Parametrization of SurfacesDefinition 1. Suppose r(u,v)=f(u,v),g(u,v),h(u,v) is a continuous vector function that is defined on a region R in the uv-plane and one-to-one on the interior of R. We call the range of r the surface S defined or traced by r. The vector function together with the domain R constitutes a parametrization o..
Spherical Coordinates
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Mathematics/Calculus
Spherical CoordinatesDefinition 1. Spherical coordinates represent a point P in space by ordered triples (r,θ,ϕ) in which r0 and 0ϕπ.위 그림과는 다른 기호를 사용하였다. r은 원점에서부터의 거리, θ는 원점과 점 P를 이은 선분과 z 축이 이루는 각도, ϕ는 cylindrical coordinates에서와 동일하게 x 축과 선분 OPxy 평면에 정사영한 선분이 이루는 각도이다.  마찬가지로 구 좌표계는 cartesian coordinates와 자유롭게 변환이 가능하다. $(x, y,..
Cylindrical Coordinates
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Mathematics/Calculus
Cylindrical CoordinatesDefinition 1. Cylindrical coordinates represent a point P in space by ordered triples (ρ,ϕ,z) in which r0. 단순히 polar coordinates에다가 z 성분만 추가한 3차원 좌표계이다. 위 그림에는 (r,θ,z)로 나타냈지만 생새우초밥집 저자의 주장을 받아들여 (ρ,ϕ,z)로 쓰도록 하자.  원통 좌표계는 좌표공간에서 cartesian coordinates과 자유롭게 변환할 수 있다. (x,y,z)(ρcosϕ,ρsinϕ,z)로 바꿀 수 있으며, 반대로 $(..