Linear algebra Definition and 999 Threads

Linear algebra is the branch of mathematics concerning linear equations such as:





a

1



x

1


+

+

a

n



x

n


=
b
,


{\displaystyle a_{1}x_{1}+\cdots +a_{n}x_{n}=b,}
linear maps such as:




(

x

1


,

,

x

n


)


a

1



x

1


+

+

a

n



x

n


,


{\displaystyle (x_{1},\ldots ,x_{n})\mapsto a_{1}x_{1}+\cdots +a_{n}x_{n},}
and their representations in vector spaces and through matrices.Linear algebra is central to almost all areas of mathematics. For instance, linear algebra is fundamental in modern presentations of geometry, including for defining basic objects such as lines, planes and rotations. Also, functional analysis, a branch of mathematical analysis, may be viewed as the application of linear algebra to spaces of functions.
Linear algebra is also used in most sciences and fields of engineering, because it allows modeling many natural phenomena, and computing efficiently with such models. For nonlinear systems, which cannot be modeled with linear algebra, it is often used for dealing with first-order approximations, using the fact that the differential of a multivariate function at a point is the linear map that best approximates the function near that point.

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  1. L

    Solve GAXPY Operations for Matrix A & Vector x

    Homework Statement Let A be an nxn matrix belonging to R and x be a vector of length k belonging to R. Find the first column of M = (A − x1I)(A − x2I)...(A − xrI) using a sequence of GAXPY’s operations. Homework Equations GAXPY: General matrix A multiplied by a vector X plus a vector Y The...
  2. RJLiberator

    Linear Algebra Proof involving Linear Independence

    Homework Statement Prove that if ({A_1, A_2, ..., A_k}) is a linearly independent subset of M_nxn(F), then (A_1^T,A_2^T,...,A_k^T) is also linearly independent. Homework EquationsThe Attempt at a Solution Have: a_1A_1^T+a_2A_2^T+...+a_kA_k^T=0 implies a_1A_1+a_2A_2+...+a_kA_k=0 So...
  3. Prof. 27

    Function Composition of Multivariate Functions

    Homework Statement This is a homework problem for my Honors Calculus I class. The problem I'm having is that though I can solve a traditional function composition problem, I'm stumped as to how to do this for multivariate functions. I read that it requires an extension of the notion of...
  4. RJLiberator

    Linear Algebra -- Is this a basis?

    Homework Statement Determine if the following sets are bases for P_2(R) b) (1+2x+x^2, 3+x^2,x+x^2) d) (-1+2x+4x^2, 3-4x-10x^2,-2-5x-6x^2) Homework Equations Bases IF Linear Independence AND span(Set)=P_2(R) RREF = Reduced Row Echelon Form The Attempt at a Solution My first question here...
  5. PcumP_Ravenclaw

    English translated German Linear Algebra book

    Dear all, Can someone please recommend a english version of a linear algebra book. "Lineare algebra, Siegfried Bosch" I don't speak German so I cannot understand the chapters. If someone can help to identify a book with similar chapters that will be very helpful. you can find the full book...
  6. Diffie Heltrix

    Norm indueced by a matrix with eigenvalues bigger than 1

    Suppose we pick a matrix M\in M_n(ℝ) s.t. all its eigenvalues are strictly bigger than 1. In the question here the user said it induces some norm (|||⋅|||) which "expands" vector in sense that exists constant c∈ℝ s.t. ∀x∈ℝ^n |||Ax||| ≥ |||x||| . I still cannot understand why it's correct. How...
  7. V

    Linear Algebra - Linear Operators

    Homework Statement True or false? If T: ℙ8(ℝ) → ℙ8(ℝ) is defined by T(p) = p', so exists a basis of ℙ8(ℝ) such that the matrix of T in relation to this basis is inversible. Homework EquationsThe Attempt at a Solution So i think that my equations is of the form: A.x = x' hence A is...
  8. W

    Linear Algebra Mastering DiffyQ and linear Algebra

    What are some books that I can use master DiffyQ and linear algebra ? I want to improve significantly in E&M and quantum mechanics. I understand that I have to practice, practice, and practice , but can you provided me with with some advice ? Thank you.
  9. kostoglotov

    What is this Matrix question asking me to do?

    It's from the chapter on Matrix Inverses... imgur link: http://i.imgur.com/8OhFzgi.jpg This is the entirety of the exercise. It's not following on from or setting anything else up. That's just number 42...what can I do with this?
  10. kostoglotov

    What Changes in the Third Pivot When a3,3 Shifts from 7 to 11 in Linear Algebra?

    Course: MIT OCW 18.06 Intro to Linear Algebra by Strang 4th edt. Question: if a3,3 is 7, and the third pivot is 5, if we change a3,3 to be 11, then the third pivot becomes _________. If you change the a3,3 to ________ then there is no third pivot. At first I thought a3,3 had to be the actual...
  11. R

    Proof: Max number of Linearly Independent Vectors

    Homework Statement Prove that a set of linearly independent vectors in Rn can have maximum n elements. So how would you prove that the maximum number of independent vectors in Rn is n?I can understand why in my head but not sure how to give a mathematical proof. I understand it in terms of the...
  12. J

    Linear Algebra Looking for a linear algebra book

    Hello all, I am about a week into a quantum mechanics course in which the instructor is mostly going to follow along with Sakurai's Modern Quantum Mechanics. However, my linear algebra is pretty rusty and I have never taken an actual course in linear algebra, I have just learned what I have...
  13. T

    Linear Algebra: Non-Singular Matrix and Zero Matrix

    Homework Statement Suppose A is non-singular (nxn) matrix. Given that AB=(zero matrix), show that B=(zero matrix). Hint: Express A as [A1, A2, ..., An] and Express AB as [AB1, AB2, ..., ABn] Homework EquationsThe Attempt at a Solution [/B] I argued that because A is non-singular, A=[A1...
  14. B

    Is R^n Euclidean Space a vector space too?

    Dear Physics Forum personnel, I am curious if the euclidean space R^n is an example of vector space. Also can matrices with 1x2 or 2x1 dimension be a vector for the R^n? PK
  15. kostoglotov

    Proving dependent columns when the rows are dependent

    I feel like I almost understand the solution I've come up with, but a step in the logic is missing. I'll post the question and my solution in LaTeX form. Paraphrasing of text question below in LaTeX. Text question can be seen in its entirety via this imgur link: http://i.imgur.com/41fvDRN.jpg...
  16. kostoglotov

    How are the x1 and x4 values determined in the solution to the matrix equation?

    Hi, rapid fire posting in this subforum I know, sorry if that's annoying. Let me know if I should space my posts out a bit more. Here's an image of the solution to a worked example (from Intro to Linear Algebra 4th by Strang) here's the imgur link: http://i.imgur.com/IG6r15H.jpg I cannot...
  17. kostoglotov

    Question about Cyclical Matrices and Coplanarity of Vectors

    MIT OCW 18.06 using Intro to Linear Algebra by Strang So I was working through some stuff about Cyclic Matrices, and the text was talking about how the column vectors that make up this cyclic matrix, shown here, are coplanar, and that is the reason that Ax = b will have either infinite...
  18. kostoglotov

    Beginner: understanding an answer

    Doing MIT OCW 18.06 using Gilbert Strang Intro to Linear Algebra. Ch 1.2 The vectors that are perpendicular to <1,1,1> and <1,2,3> lie on a ___________. I would have said "plane". I've worked with vectors in calculus, and if you take the cross product of those two vectors you get a vector...
  19. kostoglotov

    How should I teach myself Linear Algebra?

    I am preparing myself for a BSEE starting next year. I have just finished Stewarts Calculus for Calc I,II,III and Diff Eqs up to solving 2nd order non-hom diff eqs by undet. coeffs, variation of parameters and power series. In high school some 15 years ago I saw some very basic linear algebra...
  20. S

    Parametric vector form of cartesian equation

    How can I find the parametric vector form of a cartesian equation under a specific condition? Cartestian equation: $$-2x-y+z=6$$ I know to find the parametric vector form we can find any 3 points P, Q and R which satisfy the cartesian equation. $$ \begin{pmatrix} x_1\\ y_1\\ z_1...
  21. E

    Linear Transformation and isomorphisms

    Homework Statement Suppose a linear transformation T: [P][/2]→[R][/3] is defined by T(1+x)= (1,3,1), T(1-x)= (-1,1,1) and T(1-[x][/2])=(-1,2,0) a) use the given values of T and linearity properties to find T(1), T(x) and T([x][/2]) b) Find the matrix representation of T (relative to standard...
  22. E

    Bases and Coordinates: B1 and B2 for [R][/3] - Homework Statement

    Homework Statement Let B1={([u][/1]),([u][/2]),([u][/3])}={(1,1,1),(0,2,-1),(1,0,2)} and B2={([v][/1]),([v][/2]),([v][/3])}={(1,0,1),(1,-1,2),(0,2,1)} a) Show that B1 is a basis for [R][/3] b) Find the coordinates of w=(2,3,1) relative to B1 c)Given that B2 is a basis for [R[/3], find...
  23. EternusVia

    Linear Algebra, Determine the Volume of the Parallelepiped

    Homework Statement What is the volume of the parallelepiped with vertices (3, 0, −1), (4, 2, −1), (−1, 1, 0), (3, 1, 5), (0, 3, 0), (4, 3, 5), (−1, 2, 6), and (0, 4, 6)? Homework Equations The volume of a parallelepiped is given by the triple scalar product, (a × b) ⋅ c The Attempt at a...
  24. SrVishi

    Linear Algebra Hoffman/Kunze VS Lang's Linear Algebra series

    Hi, I want to learn Linear Algebra in its most rigorous and expansive form. I have narrowed down to two books (well, one is a series). On one hand, I want to try Linear Algebra by Hoffman/Kunze, but my school's library has Lang's Introduction to Linear Algebra, and his second book on the...
  25. E

    Solving Vectors & Axioms Homework

    Homework Statement Let V be the set of all ordered pairs of real numbers. Suppose we define addition and scalar multiplication of elements of V in an unusual way so that when u=(x1, y1), v=(x2, y2) and k∈ℝ u+v= (x1⋅x2, y1+y2) and k⋅u=(x1/k, y1/k) Show detailed calculations of one case...
  26. L

    Linear Algebra II - Change of Basis

    Homework Statement From Linear Algebra with applications 7th Edition by Keith Nicholson. Chapter 9.2 Example 2. Let T: R3 → R3 be defined by T(a,b,c) = (2a-b,b+c,c-3a). If B0 denotes the standard basis of R3 and B = {(1,1,0),(1,0,1),(0,1,0)}, find an invertible matrix P such that...
  27. perplexabot

    Linear algebra and choosing training vector

    Hey all. So I have been reading this article and have a question I would like to ask. I will be referring to this article extensively so it would be kind of you to open it: http://www.ee.ucr.edu/~yhua/MILCOM_2013_Reprint.pdf I believe reading the article is not required to answer my questions...
  28. Samuel Williams

    Linear Algebra - Transformation / operator

    Homework Statement Let T:V→V be a linear operator on a vector space V over C: (a) Give an example of an operator T:C^2→C^2 such that R(T)∩N(T)={0} but T is not a projection (b) Find a formula for a linear operator T:C^3→C^3 over C such that T is a projection with R(T)=span{(1,1,1)} and...
  29. kostoglotov

    Will linear algebra help me in more advanced diff eqs study?

    I just finished up Stewart's Calculus Textbook, and the last section was on solving 2nd Order Non-Homogeneous Diff Eqs using power series. I've looked through Paul's Calculus page in the Differential Sections, and can see that there is still a lot more beyond Stewart's that I'd like to study...
  30. T

    Get matrix A from a series of elementary matrices

    1. Get A from its inverse3. I believe it has something to do with the theorem that states: E1E2E3...EkA=I
  31. K

    Foundations Theoretical Books on Mathematics

    What are some rigorous theoretical books on mathematics for each branch of it? I have devised a fantastic list of my own and would like to hear your sentiments too. Elementary Algebra: Gelfand's Algebra Gelfand's Functions & Graphs Burnside's Theory of Equations Euler's Analysis of the...
  32. K

    Physical significance of Eigenvalues and Eigenvector?

    I want to know what exactly Eigen value imply. What is its Physical significance ? Physical significance of eigen vector? Does eigen value concept apply in signal processing or evalvating frequency response off a system?
  33. V

    Linear Algebra Gentle Introduction to Linear Algebra

    Does anyone know of any gentle, introductory books to LA that assume little prerequisites, even in the way of vectors and matrices? I want something that will give intuition and reasonable proofs, and will provide enough background for something like computational neuroscience. I do not know...
  34. Lagraaaange

    Linear Algebra vs Matrix Algebra? Which to pick

    In my school LA requires a pre req proof class vs matrix algebra which doesn't. Would matrix algebra even be worth taking?
  35. F

    Linear Algebra vector functions LI or LD

    Homework Statement Determine whether or not the vector functions are linearly dependent? u=(2t-1,-t) , v= (-t+1,2t) and they are written as columns matrixes. Homework Equations Wronskian, but I don't think I should use it because I need to take derivatives so it doesn't seem like it would...
  36. O

    MHB How Can We Construct a Unique Linear System From Given Conditions?

    Construct a linear system determined by four numbers whose sum is 40, with the first three numbers adding up to 20 and the last three to 30. a) Explain why this system has infinitely many solutions. b) Add another condition on the numbers so that a unique solution can be found and then find...
  37. B

    Seeking Your Advice on My Course Planning

    Dear Physics Forum advisers, I am a rising college junior in U.S. with a major in mathematics, and an aspiring applied mathematician. I apologize for this sudden interruption, but I wrote this email to seek your advice on my current problem on the course selection. I will very soon be...
  38. Finesagan

    Would you say my course-load is overwhelming?

    Hello I am going to be a Sophomore in the upcoming fall semester. For the past couple of days I have been trying to decide if I should take another math class next semester. I am passionate about both math and physics so the lack of humanities does not bother me and honestly I am happier in the...
  39. I

    Proving a linear algebra equation

    I am having trouble proving that two multivariate formulas are equivalent. I implemented them in MATLAB and numerically they appear to be equivalent. I would appreciate any help on this. Prove A = B A = (Σπ^-1 + Σy^-1)^-1 * (Σπ^-1*π + Σy^-1*y) y = π+ X*β Σπ =τ*Σ Σy = X' * Σβ * X + ΣεB =...
  40. raay

    Linear Algebra - Change of Basis

    Hi please i need help in number 3 of the tutorial questions. It is not an assignment its just a tutorial (read title in the image). I am currently studying for my final and i need help in (3b). the only way I am thinking of solving this questions is to use the equation given in part (d). But...
  41. D

    Java Eigenword embeddings and spectral learning; I'm a beginner....

    Hi everyone, I am a mathematics undergraduate and I'm currently doing an internship at the informatics department of a university. I am well and truly out of my depth. My supervisor has assigned me tasks which include Java (a language I'm having to quickly pick up, having only used python/R)...
  42. Amy1127

    Is it a bad idea to take 19 units in 16 weeks, or delay O-Chem to next term?

    In order to transfer on time from community college and prepare for the MCAT I have to really scrunch my classes. I was planning on taking Calc 3, Liner Algebra, O Chem 1, and Physics 1 (mechanics) at a whopping total of 19 units in 16 weeks. Is this doable? I would not be working and all of my...
  43. H

    Linear Algebra: Characteristic Equation Factoring

    Homework Statement If I have the characteristic equation: -λ3 + 3λ2 + 9λ + 5 And I'm told that one of its eigenvalues is -1. How do I find the rest of the eigenvalues? Homework Equations -λ3 + 3λ2 + 9λ + 5 The Attempt at a Solution The furthest I can get is: -λ3 + 3λ2 + 9λ + 5 = (λ + 1) x...
  44. M

    Linear Algebra Thoughts on Linear Algebra with Applications / 5e Bretscher

    Hey y'all! I am taking my first linear algebra course next semester and we are using Bretscher's book. I have heard some pretty awful things about the way it is laid out, so I would like to hear your thoughts on the text. For some background information I have completed Calculus 1-3 (using...
  45. C

    Tips for proof based linear algebra?

    What would be a good way to prepare for a final linear algebra exam (vectors, planes, matrices) where every question is asking for a proof? Thanks
  46. M

    How useful was Linear Algebra II after Linear Algebra I?

    I am a Physics major looking into Mathematical Biology (perhaps) in the future, and regardless of where I go, I'm trying to build a solid math background for myself. I've taken (or plan to take): Linear Algebra I Calculus I, II, III, IV ODE Non-linear ODE PDE Complex Variables (I will...
  47. L

    How to represent hidden measurement by mixture of unitaries

    Dear all, I have struggle for the problem for 2 days... And searched a lot materials on web but still can't solve for it. Question, A hidden measurement with n distinct outcomes is the average 2^(n-1) unitary maps. If it's too elusive, how about the case when n=2.
  48. J

    What Boundary Conditions Are Needed for Time-Dependent Hermitian Operators?

    Hello, could you please give me an insight on how to get through this proof involving operators? Proof: Given an eigenvalue-eigenvector equation, suppose that the vectorstate depends on an external parameter, e.g. time, and that over it acts an operator that is the fourth derivative w.r.t...
  49. B

    Taking Real Analysis, Abstract Algebra, and Linear Algebra

    Dear Physics Forum advisers, I am a college sophomore in US with a major in mathematics, and an aspiring algebraic number theorist and cryptographer. I wrote this email to seek your advice about taking the Analysis I (Real Analysis I), Abstract Algebra I, and Linear Algebra with Proofs. At...
  50. B

    Linear Algebra Seeking Recommendation on Linear Algebra Textbooks

    Dear Physics Forum personnel, I am a college sophomore in U.S. with a major in mathematics and an aspiring algebraic number theorist. I wrote this email to seek a recommendation on one or two outstanding linear algebra textbook that can supplement the Linear Algebra (Friedberg et al.), which...
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