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visits member for 3 years, 7 months
seen Dec 16 at 12:29

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Dec
9
awarded  Excavator
Dec
9
revised Does the curvature determine the metric?
log -> \log, cos -> \cos, sin -> \sin
Dec
9
suggested approved edit on Does the curvature determine the metric?
Nov
16
comment How to find $x$ such that $\tan5x=\tan x$ and $\sin5x=\sin x$?
You are welcome :)
Nov
16
revised How to find $x$ such that $\tan5x=\tan x$ and $\sin5x=\sin x$?
sin to \sin, x to $x$
Nov
16
suggested approved edit on How to find $x$ such that $\tan5x=\tan x$ and $\sin5x=\sin x$?
Nov
16
revised How can I solve this infinite sum?
deleted 2 characters in body
Nov
15
answered When will $AB=BA$?
Sep
24
awarded  Autobiographer
Aug
12
comment What is the oldest open problem in geometry?
I would like to see an animation for a periodic orbit in an obtuse triangle.
Jul
24
revised Probability with Uniform Distribution with Multiple Variables
texified the body
Jul
24
suggested approved edit on Probability with Uniform Distribution with Multiple Variables
Jul
11
comment Limit of the integral: $\int_0^{\pi/2}\beta^\alpha\exp\left(-\beta\cos(\theta)\right)d\theta$
Shouldn't it be $\lim_{\beta\to+\infty}J_0(\beta)=0$? Illustration.
Jul
4
comment 'Obvious' theorems that are actually false
You may be interested in these books: Counterexamples in Analysis, Counterexamples in Topology, and Counterexamples in Probability.
Jul
2
comment How to prove that: $\tan(3\pi/11) + 4\sin(2\pi/11) = \sqrt{11}$
How did you reach the $\sum_i \omega^{2i}=0$?
Jul
2
awarded  Curious
Jun
19
revised Find an invertible matrix $P$ and a diagonal matrix $D$ such that $D=P^{−1}AP$?
Texify the title
Jun
19
suggested approved edit on Find an invertible matrix $P$ and a diagonal matrix $D$ such that $D=P^{−1}AP$?
Jun
19
comment How to evaluate the following integral? $\int \ln(e^x + c)~\mathrm dx$
When faced with $\int f(e^x)\,\mathrm{d}x$, try transform it into $\int u^{-1}f(u)\,\mathrm{d}u$.
Jun
19
comment Clarification on optimization problem
I think for any $\alpha_k$, the objective function is linear. Given that the constraint is also linear, the optimum lies in some corner point. Since $\alpha_5=1$ violates the constraint, so $\alpha_5=0$.