bio  website  suvrit.de 

location  Internet  
age  
visits  member for  4 years, 5 months 
seen  1 hour ago  
stats  profile views  8,714 
Researcher in Optimization, Machine Learning, etc.
Hobbyist in a small fraction of the world of Inequalities, Matrix Analysis, Noncommutative polynomials.
I'm here mostly to learn old and new mathematics!
1d

comment 
Projected Alternating Minimization
No, it does not. Have a look at the explicit example in Fig. 1 here: www3.interscience.wiley.com/cgibin/fulltext/117874500/PDFSTART 
1d

comment 
Does this symmetrization operator have a name? Any theory?
I think this may be called a "polarization operator"  see e.g., page 6 of Gurvits' paper: arxiv.org/abs/math/0510452v3 
1d

reviewed  Close Difference between Principal Component Analysis(PCA) and Singular Value Decomposition(SVD)? 
2d

comment 
Is this parametric inequality true?
@TerryTao: Curiously, checking $\log(\cosh(x))/x^2$ is decreasing also showed up here, though again not without calculus: mathoverflow.net/questions/40334/… 
Jan 27 
comment 
Finding sparsest solution of a linear system
Search for: Iterative Hard Thresholding  that works as a reasonable heuristic (with some guarantees under compressed sensing style assumptions); in any case, something that you can code up in 3 lines of Matlab. 
Jan 26 
reviewed  Close the triangle inequality for shortest paths of graphs 
Jan 25 
reviewed  Close Ky Fan norms and nuclear norm 
Jan 23 
comment 
Subadditivity of the square root for matrices
@GottfriedHelms: Yes, for commuting matrices, the question will boil down to $a^r  b^r \le ab^r$ for $a,b \ge 0$. 
Jan 21 
reviewed  Close Why Laplacian Matrix need normalization and how come the sqrt of Degree Matrix? 
Jan 21 
reviewed  Close Analytic minimization of linear algebraic expression with nonlinear constraints 
Jan 21 
reviewed  Close Vanishing Points using Homogeneous Coordinates 
Jan 20 
comment 
Computation Complexity for Golden Section method
The computational complexity here is not referring to arithmetic complexity but rather oracle complexity, so that the golden section method, which converges to an $\epsilon$accurate solution at a linear rate (also known as geometric / exponential convergence in numerical literature), will make $O(\log (1 / \epsilon) )$ calls to the oracle (to compute the value of $f(x)$)  thus @Shamisen's pointer is sufficient. 
Jan 17 
comment 
Subadditivity of the square root for matrices
@MateuszWasilewski: Lower bounds on $\sigma_n$ are just too useful to be easily had :)  even the majorization result that I cited was quite nontrivial and took a few years of effort to get proved! 
Jan 17 
revised 
Subadditivity of the square root for matrices
added explicit example and more detailed citation to result that holds. 
Jan 16 
reviewed  Close Sum of Log Normal random variables 
Jan 16 
reviewed  Close QR decomposition of matrix 
Jan 16 
answered  Subadditivity of the square root for matrices 
Jan 16 
revised 
Eigenvalues of product of two symmetric matrices
changed majorization to weak maj 
Jan 9 
awarded  referencerequest 
Nov 29 
awarded  Enlightened 