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awarded  Popular Question
Apr
23
comment Two similar integrals
yes, thanks, corrected
Apr
23
revised Two similar integrals
added 58 characters in body
Apr
21
comment Two similar integrals
(I assumed that $i$ in front of $y_j$ denotes the imaginary unit)
Apr
21
answered Two similar integrals
Apr
16
comment Is there a closed form for $\sum_{k=0}^n \frac{x^k}{k!}$?
It's a Taylor polynomial of $e^x$, so you can use the integral form of the remainder (this way you just get the answers below)
Apr
7
comment Conjecture on matrix with reciprocal principal minors
Yes, clear now, thank you
Mar
25
comment Two minimization problems using singular value decomposition
Note that the matrix $Q$ produced by $q_0$ and $q_1$ can be any square matrix. If det(Q)≤0, then, I think $\max_{A\in SO(n)} tr(A^TQ)$ is equal to $\sigma_1+\sigma_2+⋯+\sigma_{n−1}−\sigma_n$, where $\sigma_1\ge\sigma_2\ge,\dots,\sigma_{n−1}\ge\sigma_n$ are the singular values of $Q$ in decreasing order.
Mar
24
revised Two minimization problems using singular value decomposition
added 135 characters in body
Mar
24
revised Two minimization problems using singular value decomposition
added 8 characters in body
Mar
24
answered Two minimization problems using singular value decomposition
Mar
20
comment Hausdorff dimension and Hausdorff measure
Since you only make the requirements for balls centered at the origin, doesn't any smooth spiral of infinite length around the origin answer affirmatively the question?
Mar
20
revised Hausdorff dimension and Hausdorff measure
typo
Mar
15
awarded  Nice Answer
Mar
5
comment Shape whose translated and scaled copies are closed under intersection
(Note that since ∂C is convex, all points but at most countably many are smooth. Also note, the analogous statement and proof hold true in any dimension )
Mar
4
answered Shape whose translated and scaled copies are closed under intersection
Feb
28
comment Covering the sphere with sectors
(I think all d but the last one should be rotated of 180 degrees to get p )
Feb
22
answered Generalized Jordan theorem and winding number
Feb
22
comment Uninteresting questions with interesting answers
It's a rather popular quotation. Here it is: I confess that Fermat's Theorem as an isolated proposition has very little interest for me, because I could easily lay down a multitude of such propositions, which one could neither prove nor dispose of. [A reply to Olbers' attempt in 1816 to entice him to work on Fermat's Theorem.] Quoted in J. R. Newman, The World of Mathematics (New York 1956).
Feb
21
comment Add a multiple of $I$ to a matrix to minimize its operator norm
in the case of A normal, I guess one gets s = the center of the minimum disk containing spec(A), right?