Mike Flynn
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 Mar 3 comment How to properly take derivatives in calculus of variations (Euler-Lagrange formula) @SanathDevalapurkar It is not obvious to me why $df'/df$ is $0$. Aug 14 comment P(tomorrow is the end of the world) =? "they both", do you mean "they all"? Aug 13 comment Mean Distance on a 3-sphere? Can you show an attempt to solve the problem? Aug 12 comment Linear programming simplex - can I have a constraint with a multiplication? so if your solution is $x = {x_1, x_2, \dots, x_n}$, you are saying all of $n_1, n_2, t_1, t_2$ are components of $x$? Aug 9 comment Understanding detailed balance (crossposted from stats) @al-Hwarizmi Markov Chain Monte Carlo, a method of approximating a probability distribution with a random walk, often used in statistics. The second sentence should read "proportional to their ratio of probability densities". I've now edited it. Jul 19 comment A method to test for uniform distribution over a convex polytope hit and run. Pick an initial point, choose a random direction, the next point is a random point between initial point and wall in that direction. Jul 19 comment A method to test for uniform distribution over a convex polytope I have no way of knowing $|P|$, in fact, this method is how I would calculate $|P|$, provided the sampling is uniform. Jun 24 comment What is the typical method for sampling uniformly in a convex polytope Not in practice actually, if you make the jump length long enough. And are you saying that there is no known way to do it quickly for 1000 dimensions? Because I was considering using CUDA to do it... Jun 18 comment Changing a basis and satisfying inequalities Ah, I now realize you must be very careful with each step... Dec 11 comment What is a covector and what is it used for? yes, so $dx([1,2])$ would be the function $dx$ acting on the vector $[1,2] \in R^2$. Dec 4 comment How would you define a geodesic in $\operatorname{SO}(2n)$ and $\operatorname{SO}(2n+1)$? Thank you for the answer. In $R^{n^2}$, do we compute the Euclidean distance as if the matrix was a long vector, adding up the squares of the components and taking a square root? Dec 3 comment What is the diameter of a manifold? @QiaochuYuan, it was a question unattached to a textbook, just "What are the intrinsic diameters of SO(2n) and SO(2n+1)?" The textbook we have been using is Frank Morgan's "Riemannian Geometry". My professor probably assumed that the choice of metric would be immediately obvious, but it is not, at least to me. Dec 3 comment What is the diameter of a manifold? @QiaochuYuan does changing it to "intrinsic diameter" change anything? Nov 19 comment What is a covector and what is it used for? Yes, I think most of my misunderstanding arose from the fact that I was interpreting $dx$ as a "length" as opposed to a function.