What is Vector space: Definition and 539 Discussions

A vector space (also called a linear space) is a set of objects called vectors, which may be added together and multiplied ("scaled") by numbers, called scalars. Scalars are often taken to be real numbers, but there are also vector spaces with scalar multiplication by complex numbers, rational numbers, or generally any field. The operations of vector addition and scalar multiplication must satisfy certain requirements, called vector axioms (listed below in § Definition). To specify that the scalars are real or complex numbers, the terms real vector space and complex vector space are often used.
Certain sets of Euclidean vectors are common examples of a vector space. They represent physical quantities such as forces, where any two forces (of the same type) can be added to yield a third, and the multiplication of a force vector by a real multiplier is another force vector. In the same way (but in a more geometric sense), vectors representing displacements in the plane or three-dimensional space also form vector spaces. Vectors in vector spaces do not necessarily have to be arrow-like objects as they appear in the mentioned examples: vectors are regarded as abstract mathematical objects with particular properties, which in some cases can be visualized as arrows.
Vector spaces are the subject of linear algebra and are well characterized by their dimension, which, roughly speaking, specifies the number of independent directions in the space. Infinite-dimensional vector spaces arise naturally in mathematical analysis as function spaces, whose vectors are functions. These vector spaces are generally endowed with some additional structure such as a topology, which allows the consideration of issues of proximity and continuity. Among these topologies, those that are defined by a norm or inner product are more commonly used (being equipped with a notion of distance between two vectors). This is particularly the case of Banach spaces and Hilbert spaces, which are fundamental in mathematical analysis.
Historically, the first ideas leading to vector spaces can be traced back as far as the 17th century's analytic geometry, matrices, systems of linear equations and Euclidean vectors. The modern, more abstract treatment, first formulated by Giuseppe Peano in 1888, encompasses more general objects than Euclidean space, but much of the theory can be seen as an extension of classical geometric ideas like lines, planes and their higher-dimensional analogs.
Today, vector spaces are applied throughout mathematics, science and engineering. They are the appropriate linear-algebraic notion to deal with systems of linear equations. They offer a framework for Fourier expansion, which is employed in image compression routines, and they provide an environment that can be used for solution techniques for partial differential equations. Furthermore, vector spaces furnish an abstract, coordinate-free way of dealing with geometrical and physical objects such as tensors. This in turn allows the examination of local properties of manifolds by linearization techniques. Vector spaces may be generalized in several ways, leading to more advanced notions in geometry and abstract algebra.
This article deals mainly with finite-dimensional vector spaces. However, many of the principles are also valid for infinite-dimensional vector spaces.

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  1. M

    How to determine the smallest subspace?

    Two examples are: Given two subspaces ##U## and ##W## in a vector space ##V##, the smallest subspace in ##V## containing those two subspaces mentioned in the beginning is the sum between them, ##U+W##. The smallest subspace containing vectors in the list ##(u_1,u_2,...,u_n)## is...
  2. Math Amateur

    MHB Basic equation in Vector Space - Cooperstein Exercise 1, Section 1.3

    I am reading Bruce Cooperstein's book: Advanced Linear Algebra ... ... I am focused on Section 1.3 Vector Spaces over an Arbitrary Field ... I need help with Exercise 1 of Section 1.3 ... Exercise 1 reads as follows:Although apparently simple, I cannot solve this one and would appreciate...
  3. G

    Find a basis and dimension of a vector space

    Homework Statement Find basis and dimension of V,W,V\cap W,V+W where V=\{p\in\mathbb{R_4}(x):p^{'}(0) \wedge p(1)=p(0)=p(-1)\},W=\{p\in\mathbb{R_4}(x):p(1)=0\} Homework Equations -Vector spaces The Attempt at a Solution Could someone give a hint how to get general representation of a vector...
  4. Steve Turchin

    Find a basis for this vector space

    Homework Statement Find a basis for the following vector space: ## V = \{ p \in \mathbb C_{\leq4} ^{[z]} | \ p(1)=p(i) ## and ## p(2)=0 \} ## (Where ## \mathbb C_{\leq4} ^{[z]} ## denotes the polynomials of degree at most 4) Homework Equations N/A The Attempt at a Solution I tried to find...
  5. Andrew Pierce

    Determining subspaces for all functions in a Vector space

    Homework Statement First, I'd like to say that this question is from an Introductory Linear Algebra course so my knowledge of vector space and subspace is limited. Now onto the question. Q: Which of the following are subspaces of F(-∞,∞)? (a) All functions f in F(-∞,∞) for which f(0) = 0...
  6. RJLiberator

    How to start this Vector Space Property Proof?

    Homework Statement Let |v> ∈ V with |v> ≠ |0>, and let λ, μ ∈ ℂ. Prove that if λ|v> = μ|v>, then λ = μ Homework Equations Vector Space Axioms The Attempt at a Solution I am struggling to begin with this one. I can think of tons of different ways to begin, but all seem to get into a hazy area...
  7. RJLiberator

    Simple Complex Vector Space Proof Clarification

    Homework Statement Let v ∈ V and c ∈ ℂ, with c ≠ 0. Prove that if cv = 0, then v = 0. Homework Equations Vector space axioms. The Attempt at a Solution Simple proof overall, but I have one major clarification question. v = 1v = (c^(-1)c)v = c^(-1) (cv) = c^(-1) 0 v = 0 My question is, in...
  8. B

    Is R^n Euclidean Space a vector space too?

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  9. C

    Simulink vector space alpha beta transformation

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  10. davidbenari

    Why is the set of cosines and sines a vector space?

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  11. S

    Smallest subspace of a vector space

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  12. popopopd

    Solution space of nth order linear ODE, n dimension Vector Space

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  13. B

    Vector Space Basis: Clarifying Linear Independence

    Hi Folks, I find this link http://mathworld.wolfram.com/VectorSpaceBasis.html confusing regarding linear independence. One of the requirement for a basis of a vector space is that the vectors in a set S are linearly independent and so this implies that the vector cannot be written in terms of...
  14. caffeinemachine

    MHB Understanding Extension of Scalars in a Vector Space

    $\newcommand{\R}{\mathbf R}\newcommand{\C}{\mathbf C}$ Low-Tech Complexification: Let $V$ be a finite dimensional vector space over $\R$. We can forcefully make $W:=V\times V$ into a complex vector space by defining addition component-wise and product $\C\times W\to W$ as $$ (a+ib)(u...
  15. M

    What is the difference between a vector and a vector space?

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  16. S

    Square-integrable functions as a vector space

    Homework Statement (a) Show that the set of all square-integrable functions is a vector space. Is the set of all normalised functions a vector space? (b) Show that the integral ##\int^{a}_{b} f(x)^{*} g(x) dx## satisfies the conditions for an inner product. Homework Equations The main...
  17. I

    Vector space, linear transformations & subspaces

    Homework Statement Let V be a vector space over a field F and let L and M be two linear transformations from V to V. Show that the subset W := {x in V : L(x) = M(x)} is a subspace of V .The Attempt at a Solution I presume it's a simple question, but it's one of those where you just don't...
  18. Dethrone

    MHB Finding a basis for a Vector Space

    4b). How can I find a basis? I was thinking of the standard basis $\{1,x,x^2\}$, but that doesn't work under the scalar multiplication definition in the vector space. EDIT: I think it is $\{0,x,x^2\}$ and we take $1$ to be the $0$ vector! $a(0)+b(x)+c(x^2)=1$ implies $a=b=c=0$. It is strange...
  19. ognik

    MHB Can a vector space also be a set?

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  20. T

    Verifying whether something is a vector space or not

    Homework Statement Hello, here is the question: "Rather than use the standard definitions of addition and scalar multiplication in R3, suppose these two operations are defined as follows. With these new definitions, is R3 a vector space? Justify your answers. a) (x1, y1, z1) + (x2, y2, z2) =...
  21. T

    MHB Matrix representation on d dimensional vector space

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  22. I

    Can Changing One Vector in a Basis Still Span the Same Vector Space?

    Homework Statement Let V be a vector space, and suppose that \vec{v_1}, \vec{v_2}, ... \vec{v_n} is a basis of V. Let c\in\mathbb R be a scalar, and define \vec{w} = \vec{v_1} + c\vec{v_2}. Prove that \vec{w}, \vec{v_2}, ... , \vec{v_n} is also a basis of V. Homework Equations If two of the...
  23. B

    What is the Zero Vector in a Vector Space with Unconventional Operations?

    Homework Statement Determine if they given set is a vector space using the indicated operations. Homework EquationsThe Attempt at a Solution Set {x: x E R} with operations x(+)y=xy and c(.)x=xc The (.) is the circle dot multiplication sign, and the (+) is the circle plus addition sign. I...
  24. I

    Is ℝ^2 with Custom Scalar Multiplication a Vector Space?

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  25. I

    Vector space and fields question

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  26. PcumP_Ravenclaw

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  27. blue_leaf77

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  28. C

    Exploring Spherical Geometry: A Question on Vector Space and Basis Formation

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  29. Dethrone

    MHB Vector Space - Proving Associativity

    Let $V$ be a vector space, and define $V^n$ to be the set of all n-tuples $(v_1, v_2,...,v_n)$ of n vectors $v_i$, each belonging to $V$. Define addition and scalar multiplcation in $V^n$ as follows: $(u_1,u_2,...,u_n)+(v_1,v_2,...,v_n)=(u_1+v_1, u_2+v_2,...,u_n+v_n)$...
  30. W

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  31. Aristotle

    Need help with proof of Vector Space (Ten Axioms)

    Let S={x ∈ R; -π/2 < x < π/2 } and let V be the subset of R2 given by V=S^2={(x,y); -π/2 < x < π/2}, with vector addition ( (+) ). For each (for every) u ∈ V, For each (for every) v ∈ V with u=(x1 , y1) and v=(x2,y2) u+v = (arctan (tan(x1)+tan(x2)), arctan (tan(y1)+tan(y2)) )Note: The...
  32. M

    Some help understanding vector space

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  33. J

    Proving the Set of Solutions for AX=B is Not a Vector Space

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  34. A

    Are Trigonometric Polynomials a Basis for a Complex Vector Space?

    I'm having trouble with a couple of things written in some notes I'm reading. Firstly, in stating examples of vector spaces, they say Trigonometric polynomials - Given n distinct (mod 2π) complex constants λ1,...,λn, the set of all linear combinations of eiλnz forms an n-dimensional complex...
  35. PsychonautQQ

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    Homework Statement Consider the set V = R^2 (two dimensions of real numbers) with the following operations of vector addition and scalar multiplication: (x,y) + (z,w) = (x+y-1, y+z) a(x,y) = (ax-a+1,ay) Show that V is a vector space Homework Equations None The Attempt at a Solution So...
  36. R

    MHB Show that Q adjoin square roots of 2, 3 is a vector space of dimension 4 over Q

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  37. T

    Proving Vector Space Axioms for f(x) = ax+b, a,b Real Numbers

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  38. V

    Prove that all integrable functions form a vector space

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  39. C

    How to calculate the projection of a function in a vector space

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  40. G

    Real Vector Space: Is Addition & Scalar Multiplication Smooth?

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  41. W

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  42. T

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  43. ChrisVer

    How Does the Metric Tensor Connect Vectors and Their Duals in Vector Spaces?

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  44. dkotschessaa

    Complex Conjugate Vector Space

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  45. S

    Showing a function forms a vector space.

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  46. K

    Prove a set is not a vector space

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  47. Mandelbroth

    Notation for the Dual of a Vector Space

    I've been reading about algebraic geometry lately. I see that a lot of authors use ##V^\vee## to denote the dual space of a vector space ##V##. Is there any particular reason for this? The only reason I could think of is that this notation leaves us free to use ##R^*## to denote the units of...
  48. Q

    MHB Commutativity in the linear transformation space of a 2 dimensional Vector Space

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  49. kq6up

    Is the Set of Polynomials of Degree ≤ 6 with a3 = 3 a Vector Space?

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  50. Math Amateur

    MHB Basis of a vector space - apparently simple problem

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