Heike
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 Jul 26 awarded Yearling Jul 26 awarded Yearling 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.