Questions tagged [pseudoinverse]
The operator which best approximates a solution to a linear system with a singular (non-invertible) matrix.: e.g., the Moore-Penrose pseudoinverse. Use when a question concerns a matrix that is probably singular.
551 questions
5 votes
0 answers
86 views
Limit as $x\to 0$ of $Z(x)=\bigl[B(x I-A)C+D(x I+A)^{-1}E\big]^{-1} $
Let $A,B,C,D,E$ be $n\times n$ complex matrices. Assume that $B,C,D,E$ are invertible, and that $A$ is singular (non-invertible). Consider the matrix-valued function \begin{equation} Z(x)=\Bigl[B(xI-A)...
0 votes
1 answer
71 views
Is this true in Hilbert spaces? $P_{T(U)}=TP_UT^+$
Let $\mathcal{H}$ and $\mathcal{K}$ be a real Hilbert space, $U\subseteq \mathcal{H}$ a closed linear subspace and $T\in\mathcal{B}(\mathcal{H},\mathcal{K})$ a continuous linear operator. I am ...
1 vote
0 answers
12 views
Discrepancy in inverse calculated using GHEP and HEP
Say we have a matrix $A = L + \beta^{2} M$, where $\beta$ is a real scalar. The matrices $L$ and $M$ are symmetric positive semi-definite and symmetric positive definite respectively. I am interested ...
0 votes
1 answer
171 views
How do you compute the solution to least-squares problem if neither $A^TA$ nor $AA^T$ nor $A$ are invertible?
For a least-squares problem find $x$ such that $\|Ax - b\|_2, A \in \mathbb{R}^{m \times n}$ is minimized, the solution of is captured by the pseudo-inverse, $$x = A^\dagger b$$ There exists three ...
0 votes
1 answer
63 views
The measure of the interval between the generalised inverse of two converging points
If I have a measure $\nu$ on $\mathbb{R}$ and $G_\nu$ is its quantile function, i.e. the generalised inverse of the cumulative distribution function $F_\nu$. I'm trying to show that for any $s\in\...
0 votes
1 answer
139 views
Proof that pseudoinverse solution of non full rank linear system is of minimum bias
Suppose the system $$\mathbf{Ax} = \mathbf{t}$$ where $\mathbf{A}$ is $m\times n$ with $m>n$ and rank-deficient (rank$(\mathbf{A})<n$). Also $\text{E}\{\mathbf{t}\}=\mathbf{Ax}$. We can form the ...
1 vote
0 answers
77 views
Generalised inverse and matrix product
Let the tall matrix ${\bf J} \in {\Bbb R}^{m \times n}$ (with $m>n$) have full column rank. Note that $\bf J$ is the Jacobian of some invertible transformation. Moreover, let the matrix ${\bf K} \...
1 vote
1 answer
98 views
Inverse or pseudoinverse in matrix identity $A = B C$ [closed]
I’m trying to understand Theorem $2.1$ from Fillmore & Williams$^\color{magenta}{\star}$ and I’m a bit confused about the notation used. In particular, the theorem involves an expression of the ...
1 vote
3 answers
170 views
Is it true that, for any $A \in \mathbb{R}^{m \times n}$, $Ax = b \iff x = A^\dagger b + v$, where $v \in N(A)$?
I wish to verify the following claim$^\color{magenta}{\dagger}$. For any $A \in \mathbb{R}^{m \times n}$, $Ax = b \iff x = A^\dagger b + v, v \in N(A),$ where $A^\dagger$ is the pseudo-inverse of $A$...
0 votes
1 answer
55 views
Norm of Moore-Penrose inverse of column-partitioned matrix
Given a matrix $M$, denote by $M^+$ its Moore-Penrose inverse. Let $B \in \mathbb{R}^{n \times r}$ and $A_1,\dots,A_t \in \mathbb{R}^{m \times n}$. Is there a way to estimate the Frobenius norm of ...
0 votes
0 answers
63 views
Solving a matrix equality using pseudo-inverse of a matrix?
I want to find an $R \in \mathbb{R}^{2 \times 2}$ such that the following equality is satisfied: $$gRg^T = I_{3 \times 3},$$ where $I_{3 \times 3}$ is the identity matrix of dimension 3 and $g \in \...
3 votes
0 answers
87 views
Minimizer $C^* = \textrm{argmin}_{C} \sum_i \lVert P P^+ A_i C^+ C - A_i \rVert_F^2$
Given $P \in \mathbb{R}^{N \times M}$ and $A_i \in \mathbb{R}^{N \times D}$ for $1 \leq i \leq k$ with $D > M$, I am looking to find the minimizer $C^* \in \mathbb{R}^{M \times D}$ of $$C^* = \...
0 votes
0 answers
21 views
What is pseudo inverse of x.T A x, where A is a positive definite symmetric matrix, and x is a column vector.
what is pseudo inverse of x.T A x, where A is a positive definite symmetric matrix, x is a column vector and x.T is the transpose of x. I am wondering whether it can be rewitten in terms of the ...
0 votes
0 answers
45 views
Drazin Inverse for special 2x2 Block Matrix
Introduction The Drazin inverse $M^D$ of a matrix $M$ is defined by the relations $$M^D M M^D = M^D,\quad M^D M = M M^D,\quad M^{k+1}M^D=M^k,$$ where the so-called index of the matrix $k=\text{Ind}(M)\...
0 votes
1 answer
83 views
Pseudoinverses in solving a matrix equation
I have the following linear algebra equation (all letters represent matrices): X * P = X * L * Q All are known except Q. I want to find Q. None of the matrices are square, but they are pseudo-...