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location  Pisa, Italy  
age  31  
visits  member for  4 years, 9 months 
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Numerical linear algebra. Mainly matrix equations and their applications (control theory, applied probability).
3h

revised 
Proving that the eigenvalues of a certain matrix product are positive
added 21 characters in body 
4h

answered  Proving that the eigenvalues of a certain matrix product are positive 
22h

comment 
Estimating the volume of a union of balls
The other problem is that convergence is very slow  if you want more than a couple of correct digits, it might take quite long even on a modern computer. 
1d

reviewed  Approve suggested edit on A question on $p$approximation property 
2d

answered  Adjusting matrix in generalized eigenvalue problem for the design of eigenfunctions 
2d

comment 
Adjusting matrix in generalized eigenvalue problem for the design of eigenfunctions
@JoonasIlmavirta Wiki: generalized eigenproblem should make the setting clearer and answer your first two questions. I second the third one though: what kind of modifications? What kind of properties? This looks too general; can you be more specific or make an example? 
2d

comment 
Block Matrix determinant
Diagonalize $1_k$. 
Aug 24 
comment 
open problems in Numerical Analysis
I don't like the adjective "good open problems". If you replace it with "famous, longstanding and important" this would make a reasonable question in my view. 
Aug 23 
comment 
Something like mathoverflow in other sciences
Someone added physicsoverflow, but it doesn't "run on the same platform as Math Overflow". The introduction should be changed to refer to that, I think  it doesn't really matter if a site uses SE rather than q2a as software backend. 
Aug 22 
comment 
Smith Normal Form for block matrix
What kind of results? Special properties of the Smith form in that case? Efficient computation? A "blockSmith" variant that works on the matrix ring of $k\times k$ matrices? 
Aug 21 
comment 
Is there an easy way to tell if all eigenvalues of a unitary or selfadjoint matrix only have eigenvalues of multiplicity two?
Are you interested in an algorithm to run on a computer or in a theoretical tool? If the former, do you want an exact result (all computations with big integers or exact rationals) or are you fine with an implementation based on floating point numbers? 
Aug 19 
answered  Why are there so few zerodimensional polynomial system solvers and is this because there is no real market for them? 
Aug 12 
revised 
How do functions operate in a Sobolev space $H^{s}$?
fixed grammar 
Aug 8 
comment 
Top specialized journals
Num Math and Math Comp are more generalist; SIAM has several journals with different scopes, but all of them rank among the top ones. In particular, SIAM Review, which mostly publishes reviews and article of interest to a broad range of researchers, and has an impressive impact factor. 
Aug 5 
comment 
On the solution of a generalized Lyapunov equation
For the record, $\F_i\otimes F_i\=\F_i\^2$, so this should coincide with the bound mentioned in the comments. 
Aug 5 
comment 
On the solution of a generalized Lyapunov equation
@JorisBierkens I did not know of this discussion, thanks for pointing it out. On the other hand, I find your sarcastic "thank you" slightly out of line; a simple link would have been sufficient. 
Aug 5 
comment 
On the solution of a generalized Lyapunov equation
It is unusual (and frowned upon) to thank other users in questions on this site, so I have removed a couple of sentences from your post. Back to business now: you say that it is 'clear' that $X$ is positive definite under those conditions; based on what exactly? The usual criterion for positivedefiniteness in the Lyapunov case ($B=A^T$, one term) is that all the eigenvalues of $A$ have negative real part, which seem different from (and contradicting with) with your proposed one. 
Aug 5 
revised 
On the solution of a generalized Lyapunov equation
removed thanks; tried to make the text flow a bit better 
Aug 4 
reviewed  Approve suggested edit on Why are they called Specht Modules? 
Aug 3 
accepted  Sensitivity of the range of a matrix 