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seen Dec 14 '12 at 11:44

Jul
26
awarded  Yearling
Jul
26
awarded  Yearling
May
28
awarded  Citizen Patrol
Feb
23
comment Gaussian formula for $n$ dimensions
I think you're missing a minus sign in the exponent.
Jan
13
comment Closed form formula for series involving derivatives of reciprocal gamma function
I've posted my comment as an answer now.
Jan
13
answered Closed form formula for series involving derivatives of reciprocal gamma function
Jan
13
comment Closed form formula for series involving derivatives of reciprocal gamma function
Since $(2k)!!=2^k k!$ the series is the Taylor series expansion of $1/\Gamma((3+p)/2)$ at $p=0$
Dec
6
comment A problem with an inscribed oval
@joriki: I assumed that the O.P. wanted a smooth curve. I probably should have mentioned that in my solution.
Dec
6
comment A problem with an inscribed oval
@J.M.: Sorry, I missed the title. I agree that mentioning ellipse in the title is misleading.
Dec
6
answered A problem with an inscribed oval
Dec
6
comment A problem with an inscribed oval
@J.M.: The question is about ovals, not ellipses. Ovals are actually constructed from pairs of arcs.
Dec
4
comment Parallelogram trigonometry
As a hint for question A, you could try applying the law of sines to two triangles with a common angle. You should end up with two equations for the sine of that common angle.
Dec
2
answered Four kissing circles
Dec
1
answered Sequences whose differences tend to $0$
Nov
29
comment projection of a sphere onto a plane
Maybe I'm misinterpreting the question here, but wouldn't it just be the points $(x,Y,\pm\sqrt{3/8-x^2-Y^2})$ for the first case and $(x,\pm\sqrt{3/8-x^2-Z^2},Z)$ for the projection along the $Y$-axis?
Nov
16
comment Improper integral; exponential divided by polynomial
Basically the same remark as for Ali's answer. If $k<0$ the contour should be closed in the lower half-plane and the integral will be zero.
Nov
16
awarded  Commentator
Nov
16
comment Improper integral; exponential divided by polynomial
you have to be careful to close the contour in the right half-plane. Since $\exp(izk)$ blows up for $Re(izk)\rightarrow\infty$ and goes to zero for $Re(izk)\rightarrow-\infty$, you should close the contour in the upper half-plane for $k>0$ and in the lower half-plane for $k<0$. Depending on the sign of $k$ you'll have either 0 or 2 poles inside the closed contour.
Nov
15
awarded  Enthusiast
Nov
14
comment Convergence of a complex series , are my estimations correct
The sum on the right-hand side of ii) doesn't converge for $|z|=1$