bio | website | fph.altervista.org |
---|---|---|
location | Pisa, Italy | |
age | 31 | |
visits | member for | 4 years, 11 months |
seen | 44 mins ago | |
stats | profile views | 2,141 |
Numerical linear algebra. Mainly matrix equations and their applications (control theory, applied probability).
Oct 20 |
comment |
College - Ecuation to solve in 3 variables (p,q,r) in [1,2]
Wow, that's homework? It looks a lot like an Olympiad-like problem at first sight. |
Oct 19 |
revised |
Strong Law of Large Numbers for arrays of partly dependent random variables
removing tag numerical analysis -- seems to have nothing to do with it |
Oct 19 |
comment |
Is the notation ${}^t g$ for the transpose of a linear transformation intended to be suggestive?
(Incidentally, unfortunately one cannot extend these operations to a fully-fledged "transposition algebra" with $T^2=1$, since $A^{1+T}\neq A^{T+1}$, i.e., $A^TA\neq AA^T$.) |
Oct 19 |
comment |
Is the notation ${}^t g$ for the transpose of a linear transformation intended to be suggestive?
In numerical linear algebra, where transposes normally go on the right, the notation $A^{-T} := (A^{-1})^T = (A^T)^{-1}$ is quite common, and on rare occasions I have seen $A^{2T}$. So there is an analogously suggestive solution even putting transposes on the right. |
Oct 18 |
reviewed | Approve suggested edit on Number of divisors of an integer of form 4n+1 and 4n+3 |
Oct 18 |
revised |
A calculus question
retagged, in case it stays open |
Oct 16 |
reviewed | Approve suggested edit on Untrustworthy people picking a random number |
Oct 14 |
answered | The eigenvectors and eigenvalues of matrix geometric mean |
Oct 13 |
comment |
How to solve a non-homogeneous quadratic matrix equation?
@RobertBryant Thanks for your consideration, but I encourage you to undelete it, I think it was useful. There is nothing wrong with two answers that give different views and information. People can upvote us both. :p |
Oct 13 |
comment |
How to solve a non-homogeneous quadratic matrix equation?
@RobertBryant I saw your answer only briefly -- why did you delete it? It looked correct to me, and it added some insight on the origin of the solution which my answer currently lacks. |
Oct 13 |
answered | How to solve a non-homogeneous quadratic matrix equation? |
Oct 13 |
comment |
How to solve a non-homogeneous quadratic matrix equation?
Are you sure about those signs? If $G$ has to be symmetric, then $GHG$ has the same signature as $H$, that is, negative definite, but $GHG=M$ tells you that it needs to be positive definite. |
Oct 13 |
reviewed | Approve suggested edit on Prime factors of the members of a certain recurrence |
Oct 11 |
answered | Approximating the action of the U(N) exponential map |
Oct 10 |
reviewed | Approve suggested edit on origami-folding tag wiki excerpt |
Oct 9 |
revised |
Computing covariance matrix from patchy data
deleted 7 characters in body |
Oct 9 |
comment |
Examples of eventual counterexamples
There are lots of answers that basically contain only the name of the result and a link to a paper/webpage; I find them very unhelpful and would like to invite the authors to put at least a quick explanation in the text of their answers. In general, link-only answers are frowned upon on many stack exchange websites. |
Oct 9 |
revised |
eigenvalue estimate of the adjacency matrix
deleted 5 characters in body |
Oct 9 |
comment |
eigenvalue estimate of the adjacency matrix
Hmm, right. :) What I wrote applies to a generic nonsymmetric nonnegative matrix. Then, in your case, moreover, the 2-norm bound is even more useless, since the 2-norm is $\lambda_\max$. |
Oct 9 |
answered | eigenvalue estimate of the adjacency matrix |