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seen Sep 5 at 16:26

Sep
5
answered Proof of trigonometric identity $\cot \theta \sec\theta= 1/ \sin\theta$
Aug
24
revised Understanding how a differential equation is solved with distributions
added 14 characters in body
Aug
23
revised Understanding how a differential equation is solved with distributions
added 4 characters in body
Aug
23
asked Understanding how a differential equation is solved with distributions
Aug
5
comment Geometric minimal distance path between 2 points via 1 area
yes in particular cases, a straight line works
Aug
5
awarded  Curious
Aug
5
revised Geometric minimal distance path between 2 points via 1 area
deleted 99 characters in body
Aug
5
comment Geometric minimal distance path between 2 points via 1 area
@achillehui nice intuition, I could also have put a more generalized elliptic sea line, and the idea is maybe to find the largest ellipse that fits in the other
Aug
5
comment Geometric minimal distance path between 2 points via 1 area
it can be the longer path or shorter path, I think. If my assumption is right, the other parallel tangent below the circle is the longer path possible
Aug
5
revised Geometric minimal distance path between 2 points via 1 area
added 85 characters in body
Aug
5
comment Geometric minimal distance path between 2 points via 1 area
One fire, one plane at an initial location, on straight sea line that the place must each before getting to the fire
Aug
4
asked Geometric minimal distance path between 2 points via 1 area
Jul
14
suggested rejected edit on Expected Number of Coin Tosses to Get Five Consecutive Heads
Jul
4
comment Combinatorics: Mean and Variance of an indicator function of items arranged in a circle.
confirmed by this matlab quick test: n=25; b=10; X = zeros(10000,1); for i=1:length(X) B = sort(randsample(n,b)); % blue balls C = diff([B; B(1)+n]); % differences to right neightbor clock-wise D = circshift(C, 1); % differences to left neightbor clock-wise X(i) = sum(C>1 & D>1); end E = mean(X) % 3.8182 V = var(X) % 2.8490
Jun
28
comment Combinatorics: Mean and Variance of an indicator function of items arranged in a circle.
I think with a circle, all $X_i$ are equivalents, the same problem with balls on a straight line would be more difficult
Jun
27
comment Proof of $\int_0^\infty \frac{\sin x}{\sqrt{x}}dx=\sqrt{\frac{\pi}{2}}$
@Tunk-Fey contour integration comes with the study of holomorphic functions (functions continuous in $\Bbb C$)
Jun
25
accepted partial derivatives of Dirac functions
Jun
25
comment partial derivatives of Dirac functions
right, indeed, $\delta = \delta_0$ and $x_i$ is null
Jun
25
asked partial derivatives of Dirac functions
Jun
21
comment Proof of $\int_0^\infty \frac{\sin x}{\sqrt{x}}dx=\sqrt{\frac{\pi}{2}}$
Thanks, awesome answer, the trick is to take this quarter circle