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22140
bio website fph.altervista.org
location Pisa, Italy
age 31
visits member for 4 years, 8 months
seen 2 days ago

Numerical linear algebra. Mainly matrix equations and their applications (control theory, applied probability).


2d
reviewed Approve suggested edit on R is regular local rings of Krull dimension 2.Can we find any ideal of height 2 different from m?
2d
comment Basis for the rational functions
@VladInfinitum It is difficult to answer without knowing your specific needs, and I am not an expert on the topic. I suggest you to look at an introductory book such as Geometric Modeling with Splines: An Introduction, Cohen, Rosenfeld, Elber, or at least take a look around on Wikipedia (Splines, B-Splines, NURBs, Spline interpolation).
2d
comment Basis for the rational functions
Actually rational functions aren't used very often in numerical analysis as a modelling tool. Splines (spaces of piecewise polynomials or rational functions, with compactly-supported bases) and their variants are more popular.
Jul
21
reviewed Approve suggested edit on noncommutative-geometry tag wiki
Jul
21
reviewed Approve suggested edit on noncommutative-geometry tag wiki excerpt
Jul
21
revised a book comparable to Development of mathematics in the 19th century by F.Klein?
grammar
Jul
16
comment Recommendations for symmetric preconditioner
I'd suggest asking this on scicomp.stackexchange.com -- the community there is more expert in numerical methods; MO is more oriented towards non-applied mathematics. Please flag your question for moderation attention to suggest migration if you agree.
Jul
15
answered Determinant of sum of Kronecker products
Jul
15
comment LU factorization for $I+A$ (A skew-symmetric)
I would be very careful in assuming this is true based on numerical examples only. The worst-case bounds for the growth factor in LU factorization of general (non-antisymmetric) matrices are quite hard to reach in practice.
Jul
14
reviewed Approve suggested edit on Proof or citation?
Jul
4
reviewed Reject suggested edit on Is there a coordinate free proof of the Morrey--Kohn--Hormander identity?
Jul
4
comment Generalising the cyclic property of the trace of a matrix
By the way, Peter Semrl has characterized the linear maps from $C^{n\times n}$ to itself that preserve many different properties, including those that [preserve similarity](www.fmf.uni-lj.si/~semrl/preprints/similarity.pdf). This problem looks related.
Jul
4
comment Generalising the cyclic property of the trace of a matrix
Other semi-trivial examples of functions with the cyclic property, but without the other ones that you ask for, are the $\ell^p$-norms of the eigenvalues.
Jul
4
reviewed Approve suggested edit on if $X$ is a vector field in $\mathbb{R}^3$ and $h$ is a periodic orbit, then $X$ have a singularity?
Jul
3
comment Matrix equation solving guidelines
$B$ should be $Q\otimes P + Q^T \otimes P^T$, without the $\operatorname{vec}$, isn't it?
Jul
3
comment Matrix equation solving guidelines
@Mahdi no, the idea works, it is just inefficient if the OP has practical solution in mind, and it seems to me that the algebra in your post is still incorrect. Please do not take the downvote as a personal thing.
Jul
3
answered Matrix equation solving guidelines
Jul
2
awarded  Curious
Jun
27
reviewed Reject suggested edit on Is the Szego projection on a codim-$k$ CR manifold an integral operator?
Jun
27
reviewed Approve suggested edit on $6$ points lie on a conic if and only if $ABC$ and $A_0B_0C_0$ are perspective