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 Mar 26 answered Large Tridiagonal Matrix - Eigenvalues Feb 17 comment Efficiently compute the trace of a sparse matrix times the inverse of a sparse matrix? @ Suvrit , yes I forgot "sparsity". Feb 14 comment Efficiently compute the trace of a sparse matrix times the inverse of a sparse matrix? @ Suvrit , very pretty post (+1, but that will not hardly change your total!). What about the complexity ? I think that it is in $O(mn^2)$ with a "not small" constant. How do you choose $m$ ? Feb 10 awarded Popular Question Feb 3 awarded Revival Jan 16 revised Non-asympototic version of Gelfand's formula deleted 1 character in body Jan 16 answered Non-asympototic version of Gelfand's formula Jan 13 comment Solving a system of equations using Gröbner basis @ user84881 , I do not know anyone who works on fields having such a big characteristic. Maple accepts only $char(K)\leq 2^{16}$. Can you write some words about your problem ? Jan 12 revised Solving a system of equations using Gröbner basis added 430 characters in body Jan 12 revised Solving a system of equations using Gröbner basis added 224 characters in body Jan 12 revised Solving a system of equations using Gröbner basis added 431 characters in body Jan 11 answered Simultaneous special orthogonal similarity problem Jan 11 answered Solving a system of equations using Gröbner basis Dec 18 awarded Revival Dec 10 awarded Revival Oct 29 comment Parameterize unitary without transpose @ Robert Bryant , indeed the proof of Prop 2 is not straightforward. We show the result over $\mathbb{C}$ and, in a second step, over $\mathbb{R}$ along the same ideas you used. That was clear for me because I knew this characterization of $\sin,\cos$ since a long time. I adopted this presentation to highlight the geometric idea behind. Yes, the Kummer's result gives the surjectivity; moreover, 1. to read Kummer's proof is much easier than to study Cartan's theory. 2. I like this "story of maths" aspect. Oct 29 comment Parameterize unitary without transpose @ Sebastian SchlechtClearly , Prop. 1 and 2 can be independently proved. About a name for $V$, I don't know. In general, the authors consider elements of $V$ and not the whole set. cf also Horn and Johnson; Matrix Analysis, Section 4.6 Oct 29 revised Parameterize unitary without transpose added 160 characters in body Oct 29 answered Parameterize unitary without transpose Oct 18 answered What is the time complexity of approximated SVD