6,737 reputation
22350
bio website fph.altervista.org
location Pisa, Italy
age 32
visits member for 5 years, 5 months
seen 12 mins ago

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

(This profile was written for Mathoverflow, but Stack Exchange insists on copying it over verbatim to other sites, where it makes less sense.)


2h
reviewed Approve A Question on 1, 2 ,3 Conjecture
4h
reviewed Approve Source for roots of matrix polynomials?
Apr
21
reviewed Approve determinants tag wiki excerpt
Apr
21
revised Functional minimization problem
better title
Apr
21
comment LQR solution when there are linear terms in the cost function?
In the LQR problems I have studied $s$ and $u$ are either sequences or functions of a real variable. Is this the case here, too? Could you please write the full equations, if so?
Apr
20
awarded  Popular Question
Apr
19
reviewed Approve descriptive-set-theory tag wiki excerpt
Apr
19
reviewed Approve Zero divisors and boundary elements of $A^{-1}$
Apr
9
accepted Non-computational software useful to mathematicians
Apr
9
accepted Factorizing a block symmetric matrix
Apr
9
accepted Should I become a Mathscinet reviewer?
Apr
9
accepted Positive definite to nonnegative
Apr
9
answered The bubble function
Apr
1
comment Solving $Ax=e_k$ for standard basis vector $e_k$, sparse $A$
Also, the numbers given in the question sound strange. If I am not mistaken with the computations, 0.00001% of nonzeros means that there are $10^7$ nonzeros in the matrix overall, one every 1000 rows. Is that the case? Would it make sense to prune out the zero rows first?
Apr
1
comment Solving $Ax=e_k$ for standard basis vector $e_k$, sparse $A$
QR seems out of question to me. Its result typically is a dense, floating-point number matrix, which would require 800 Terabytes only to store it.
Mar
29
revised Lagrangian submanifold of a Calabi-Yau manifold
expanded abbreviation in the title, for clarity
Mar
27
answered Two equivalent descriptions of a physical system yielding a non-trivial mathematical formula
Mar
25
answered The maximal eigenvalue of a symmetric Toeplitz matrix
Mar
24
awarded  Enlightened
Mar
24
awarded  Nice Answer