Questions tagged [rank-1-matrices]
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62
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Characteristic polynomial of convex combination
Given the following lemma on rank-$1$ matrices which I think I understand
How could I deduce the following on the characteristic polynomial of $A_s$? I don't get it just using multilinearity of ...
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3
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Let A be a complex $n \times n$ matrix with rank(A) = 1. Why is the minimal polynomial $x(x-Tr(A))$? [duplicate]
We know $rank(A) = 1$ so I have $n-1$ eigenvalues which are $0$
So my characteristic polynomial is $(x-0)^{n-1}(x-a) = x^{n-1}(x-a)$ with $a$ the last eigenvalue to determine.
Now, I found on some ...
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Trace of square of a rank-$1$ Hermitian matrix ${\bf A} = {\bf a}{\bf a}^H$
Given matrix ${\bf A} = {\bf a}{\bf a}^H$, where ${\bf a}$ is a complex column vector. Are the following correct?
${\rm Tr}({\bf A}) = {\rm Tr} \left( {\bf a}{\bf a}^H \right) = {\rm Tr}({\bf a}^H{\...
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Equivalence between first-order optimality conditions for rank-$1$ constraint and quadratic form
When simplified down, my optimization problem has the following structure
$$\underset{x\in\mathbb{R}^n}{\arg\min} \quad \left\| b - A\operatorname{vec} \left( x x^\top \right) \right\|_2^2$$
I am ...
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Construct biorthogonal basis for rank-1 matrix? [closed]
Consider a rank-1 matrix $\mathbf{A}=\lambda\mathbf{u}\cdot\mathbf{v}^\mathsf{T}$ where $\lambda,\mathbf{u},\mathbf{v}$ are known. Let $\mathbf{A}$ be of size $N\times N$.
(Edit: A direct consequence ...
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Prove that there is a rank one matrix $B$ so that $Bx = y$ where $B$ has matrix norm $1$
Let $\lVert \cdot \rVert$ denote a norm on $\mathbb{C}^m$. Define the dual norm $\lVert \cdot \rVert '$ by $\lVert x\rVert' := \sup_{\lVert y\rVert = 1} |y^* x|,$ where $y^*$ is the conjugate ...
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On the linear system $A x = 0$ when $A$ is rank-one
From Strang's textbook:
For rank-one matrices, we have that $u(v^Tx)=0 \implies v^Tx=0$. Why does this follow?
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Connection between rank one matrices and rank one functions
Let $X$ be a finite set and $\mathbb{F}$ be a field. We say that a function
$f: X\times X \to \mathbb{F}$ is rank one if $f$ is of the form $(x,y) \mapsto a(x)b(y)$ for $a,b: X \to \mathbb{F}$. (See ...
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Frobenius and spectral norms of rank-$1$ matrices
How to prove that $$\left\lVert x y^{\ast}\right\rVert_F = \left\lVert x y^{\ast}\right\rVert_2 = \left\lVert x\right\rVert_2 \left\lVert y\right\rVert_2$$ where $\forall x, y \in \mathbb{C}^n$?
I ...
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Loewner order and rank-$1$ matrices
The Loewner order is defined over the set of Hermitian matrices as $A \leq B$ if and only if $B - A$ is positive semidefinite. If $B$ is a rank-$1$, positive semidefinite matrix, what are the matrices ...
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Why is the matrix $x y^T$ rank one? [duplicate]
I am reading the definition of almost diagonal matrix:
DEFINITION. A matrix $A$ is almost diagonal (a.d.) if there exist a diagonal matrix $D$ and vectors $x$ and $y$ such that $$A=D+xy^T$$ That is, $...
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Explaining the non convexity of rank 1 matrix
I understand from this post:
How can we show/prove that a rank-$1$ matrix is non-convex?
that a rank-1 matrix is non convex but I don't understand the proof. I know that the summation of two convex ...
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Is this rank-$1$ (complex) matrix positive semidefinite?
In Is this rank-$1$ matrix semidefinite?, I have seen that $X = xx^T$ is PSD when $x$ is real. What about the case when $X$ is Hermitian?
I know that it is PSD but I'm not exactly sure how to prove it....
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What does "rank one" in "rank one constraint system" mean?
Although rank one constraint system (r1cs) is heavily used in zero-knowledge proofs, I didn't find anywhere details on where the rank comes from.
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Is the multiplication of rank one matrices always yield rank one matrix? [closed]
Let's say we have infinite multiplication of rank one matrices. Does this yield rank one matrix?
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Can this $3 \times 3$ tridiagonal Toeplitz matrix be rank-$1$?
I am trying to determine whether the following tridiagonal $3 \times 3$ matrix can have a rank of $1$.
$$\begin{bmatrix}a&b&0\\b&a&b\\0&b&a\end{bmatrix}$$
For $a = b = 0$, the ...
user1003610
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$3 \times3$ matrices with rank $1$ or $2$ are manifolds
Let $M, N \subset \mathbb{R}^{n}$ be sets of matrices $3 \times 3$ with rank $1$ and $2$, respectively. Show that $M$ and $N$ are manifolds such that dim $M=5$ and dim $N=8$.
I have thought about ...
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Find out the convex hull of the set $\left\{\pm \mathbf{u} \mathbf{u}^{T} \mid\|\mathbf{u}\|=1\right\}$ in a compact form ($u$ is a n-d vector)
According to the answer from @Cloudscape
The first step of finding the convex hull of a given set would be to visualize the convex hull and guess it.
The second step would be to prove your guess ...
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$2$-norm of a rank-$1$ matrix
I want to prove that $\|A\|_2 = \|x\|_2\|y\|_2$ given that $A = xy^T$ is a rank one matrix. This is my incomplete attempt so far, I get stuck when I need to take into account the spectral radius of ...
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Given rank-$1$ matrix $A$, how to compute $A^{100}$?
$$A = \begin{bmatrix} 6 & 4\\ -6 & -4\end{bmatrix}$$ Find $A^{100}$.
I tried to find it using diagonalization, but as it is a singular matrix so one of eigenvectors came out zero. How $A^{100}...
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Convex hull of rank-$1$ matrices is the nuclear norm unit ball
Let
$$A := \left\{ u v^T : u \in \mathbb{R}^m, v \in \mathbb{R}^n, \|u\|_2 = \|v\|_2 = 1 \right\}$$
I would like to show that
$$\textrm{conv}(A) = B_* := \left\{ X \in \mathbb{R}^{m \times n}: \|X\|_* ...
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Find a linear combination of matrices that has rank 1
Consider several linearly independent matrices $A_k \in \mathbb R^{m \times n}$ and the following equation
$$
\operatorname{rank} \left(A_0 + \sum_{k=1}^r c_k A_k\right) = 1.
$$
Here $A_k$ are fixed, $...
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$\det(I+A)=1+\operatorname{Tr}(A)$ if $\operatorname{rank}(A)=1$
Let $A$ be a complex matrix of rank $1$. Show that $$\det (I+A) = 1 + \operatorname{Tr}(A)$$ where $\det(X)$ denotes the determinant of $X$ and $\operatorname{Tr}(X)$ denotes the trace of $X$.
Any ...
user598858
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$\lambda_{\min}$ and $\lambda_{\max}$ of rank-1 sum of matrices
It is explained from previous posts1,2 that for a rank-$1$ matrix $x_ix_i^T$ we have $\lambda_{\max} (x_ix_i^T)=1$ and $\lambda_{\min} (x_ix_i^T)=0$ with single and $N-1$ algebraic multiplicity, ...
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Rank-1 matrix with two dependent rows?
I want to know what could be the possible rank of a matrix, which is constructed from a same vector but have two repeating rows.
Lets say I have a vector $$x=\begin{bmatrix}1 &a &1& b\end{...
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Number of rank 1 matrices with $0/1$ entries?
How many rank $1$ matrices in $\mathbb Z^{m\times n}$ are there if entries are restricted to $\{0,1\}$?
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Finding rank-$1$ matrix
Let $$S = \frac{1}{12} \begin{pmatrix} 1 & 10 & 1 \\ 5 & 2 & 5\\ 1 & 2 & 9\end{pmatrix}$$ Find a rank-$1$ matrix $R$ so that $$ M = S + R $$ will have the same eigenvalues as $...
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Minimal "dominating" rank-$1$ matrix
Given a matrix ${\bf A} \in \Bbb R^{n \times n}$, I would like to find a minimal rank-$1$ matrix ${\bf B} \in \Bbb R^{n \times n}$ such that the Frobenius norm of $ \| {\bf A} - {\bf B} \|_{\text{F}}...
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Finding the best rank-one approximation of the matrix $\bf A$
I have computed the singular value decomposition (SVD) of the following matrix $A$.
$$ {\bf A} := \begin{bmatrix}1&2\\0&1\\-1&0\\\end{bmatrix} = \underbrace{\left[\begin{matrix}0 & \...
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How can we show/prove that a rank-$1$ matrix is non-convex?
In my optimization problem, I have a matrix $X = v v^H$ where $H$ denotes the complex conjugate transpose and $v \in \mathbb C^n$. This is a rank-$1$ matrix. In the published literature, it is ...
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Find the eigenvalues and eigenvectors of the matrix $A = uu^t$, where $u\in\mathbb{R}^n$
Find the eigenvalues and eigenvectors of the matrix $A = uu^t$, where
$u\in\mathbb{R}^n$
The multiplication will give me a $n \times n$ matrix like this:
$$\begin{bmatrix}
u_1^2 & u_1 u_2 &...
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Rank one orthogonal projector matrix.
My text is covering projector matrices while building up to Householder triangularization. The main topic of discussion is orthogonal projector matrices that satisfy
\begin{align} P &= P^2 \...
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Frobenius and operator norms of rank 1 matrices
$\newcommand{\opnorm}[1]{\left\| #1 \right\|_{\mathrm{op}}}
\newcommand{\norm}[1]{\left\| #1 \right\|}$
Suppose we have $X = x_1 x_2^\top \in \mathbb{R}^{n \times d}$ a rank-1 matrix which is non-...
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Hessian with rank one
Let $\boldsymbol{\mathsf{H}}$ be the Hessian of the function $F(\boldsymbol{x})$. If this function is of the form
$$
F(\boldsymbol{x}) = f(\hat{\boldsymbol{\omega}}\cdot\boldsymbol{x})
$$
with some ...
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Does $\det(I+A) = 1 + \mbox{tr}(A)$ hold if $A$ is a rank-$1$ complex matrix? [duplicate]
If $A$ is a complex $n \times n$ matrix of rank $1$, then $$\det(I+A) = 1 + \mbox{tr}(A)$$
How to approach this problem?
Rank-$1$ matrices have special properties. Also, thinking about the ...
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All rank-1 matrices have an SVD
I have a rank-$1$ matrix $A \in \mathbb{R}^{m \times n}$ and a vector $u$ in its image. I could prove that the columns of $A$ are multiples of a vector $u$, and that $A$ can be written as $A = \alpha ...
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How can I solve "average" best rank-$1$ approximation?
Assume I want to minimise this
$$ \min_{x,y} \left\| A - x y^T \right\|_{\text{F}}^2$$
then I am finding best rank-$1$ approximation of $A$ in the squared-error sense and this can be done via the SVD, ...
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Approximating a given matrix with a rank 1 matrix Hadamard product with another given matrix
Let $A,B\in\mathbb{R}^{m\times n}$ be matrices with all positive entries. I want to compute the following minimum.
$$\min_{\vec{u}\in\mathbb{R}^m,\ \ \vec{v}\in\mathbb{R}^n} \ \ \sum_{i=1}^m \sum_{j=1}...
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Factoring a given rank-$1$ matrix
Suppose you have a $n \times 1$ column vector
$$a=\begin{bmatrix}a_1\\{a_2}\\ \vdots\\{a_n}\end{bmatrix}$$
and a $1 \times m$ row vector
$$\quad b=\begin{bmatrix}b_1 & b_2 & \ldots & ...
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Recover vector $x$ from rank-$1$ matrix $Q=xx^H$
Let the matrix $Q \in\mathbb{C}^{n \times n}$ be known. It is also known that $Q=xx^H$, where $x=[x_1,\ldots,x_n]^T$ and $x^H$ is its conjugate transpose. What is $x$? How to recover it?
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Element-wise upper bound by rank-1 matrix
I would like to solve the following optimization problem for vectors $\mathbf{u} \in \mathbb{R}^m$ and $\mathbf{v} \in \mathbb{R}^n$, given a matrix $\mathbf{h} \in \mathbb{R}_{\geq 0}^{m \times n}$ ...
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Applications where rank-1 matrices are useful
I am trying to list down applications where having a rank-1 matrix is advantageous. I know only of 2D convolution which boils down to a series of 1D convolutions if filter response is separable.
Can ...
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Is the product of a diagonal matrix and a rank-$1$ matrix still rank-$1$?
First let me make two statements to give my question the proper context.
Consider $D$ a diagonal matrix and $u v^T$ a rank 1 matrix.
From my current knowledge there exist computationally cheap ...
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Some basic questions regarding rank-$1$ matrices
If an $n \times n$ matrix $B$ has rank $1$, and $A$ is another $n \times n$ matrix, then why does $A B$ also have rank $1$? This showed up in a solution that I read through, but it doesn't seem like ...
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A rank-one matrix is the product of two vectors
Let $A$ be an $n\times m$ matrix. Prove that $\operatorname{rank} (A) = 1$ if and only if there exist column vectors $v \in \mathbb{R}^n$ and $w \in \mathbb{R}^m$ such that $A=vw^t$.
Progress: I'm ...
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Rank-$1$ matrices
I am struggling to understand the lecture notes (I have not learned linear algebra, but I do know some basic stuff). I understand the concept of rank of a matrix. A rank of matrix $A$ is given by the ...
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How to get orthogonal rank-$1$ approximations?
Given $k$ matrices $A_1, A_2, \dots, A_k \in {\Bbb R}^{m \times n}$, I would like to find the matrices $\tilde{A}_1, \tilde{A}_2, \dots, \tilde{A}_k$ such that
$\tilde{A}_i$ is a rank-$1$ ...
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Given matrices $A$ and $B$, how can I find a scalar $s$ that makes $A + s B$ rank-$1$?
Given $3 \times 3$ matrices $A$ and $B$, how can I find a scalar $s$ that makes the matrix $A + s B$ rank-$1$? Is there a method using singular value decomposition or eigenvalues?
Thanks!
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Singularity of a conic combination of rank-$1$ matrices
Given rank-$1$ square matrices $A_1, A_2, \dots, A_n$, determine if there exists $x \in \mathbb R_{>0}^n$ such that
$$ \sum_{i=1}^n x_i A_i = x_1 A_1 + \cdots + x_n A_n $$
is singular, or decide ...
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Generation of rank-$2$ matrices from a dictionary of rank-$1$ matrices
Consider the set
$$\mathcal{D} = \left\{ \mathbf{A} \in \mathbb{C}^{2 \times 2} \mid \mbox{rank} (\mathbf{A}) = 1, \|\mathbf{A}\|_{F} = 1 \right\}$$
of all $2 \times2$ rank-$1$ matrices with unit norm ...
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