Chris Culter
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 1d revised Enumerating Bianchi circles add paragraph, vis tag 1d comment Is there any formal or scientific use for a base 7 numeral system? Yes, in hexagonal image processing, but I'm not familiar with the details. 2d asked Enumerating Bianchi circles Apr21 answered If complex numbers can be represented as vectors, why can't we define $2$-dimensional vector division just as complex division? Apr10 comment What is the general solution to $\sin\theta=\frac12$? Why do you say your solution is wrong? Mar31 comment Some clarifications on analytic continuation of Riemann's Zeta function on $\frac 1 2$ For the first question, see math.stackexchange.com/questions/947158/… and math.stackexchange.com/questions/1082139/… Mar24 revised For what $n$ does $[\log_21]+[\log_22]+[\log_23]+\dotsb+[\log_2n] = 1538$? rolled back to a previous revision Mar4 comment Prob. 5 in Exercises after Sec. 17 in Munkres' TOPOLOGY, 2nd ed.: How to prove this result in a general ordered set? Try a few examples of intervals in different ordered sets. For which does equality hold? What is the pattern? Mar2 comment Can $10^{2k+1}+ 1$ be a perfect square? Regarding recent edits, if you'd like to ask about $3^n$, please ask a new, separate question. Mar2 revised Can $10^{2k+1}+ 1$ be a perfect square? rolled back to a previous revision Feb27 comment Why can you chose how to align infinitely long equations when adding them? Arbitrary rearrangements do require absolute convergence to preserve the sum. But to address the OP, shifting only requires convergence. Also, adding series term-by-term only requires convergence. Moreover, some common summation methods for divergent series also respect these two operations, making them "stable" and "linear". Cesaro summation and Abel summation are good examples. So the operations are surprisingly forgiving! Feb27 comment $f$ convex, $\lim_{x\to\infty}\frac{f(x)}{x}=0$, then $f$ is constant This is a slightly stronger result than math.stackexchange.com/questions/518091, and Henning Makholm's approach there works here as well. Feb27 answered Can $10^{2k+1}+ 1$ be a perfect square? Feb24 comment NP-hard optimization problems for which approximations would be useless? Produce a proof certificate for [insert famous conjecture] containing as few errors as possible? Feb23 comment Why line integral of f(x.y)=(x.y) is not zero along the circle? How did you compute the integral? Feb23 revised Find the numbers that have an inverse modulo 11 title Feb22 revised Prove the $n$th Fibonacci number is the integer closest to $\frac{1}{\sqrt{5}}\left( \frac{1 + \sqrt{5}}{2} \right)^n$ transcribe images; place expression in title Feb22 comment Showing that $f_n$ is the number closest to $\frac{1}{\sqrt{5}}(\frac{1+\sqrt{5}}{2})^n$ Whoops, I was a little too quick to answer this question. Will mark the duplicate. Feb22 answered Showing that $f_n$ is the number closest to $\frac{1}{\sqrt{5}}(\frac{1+\sqrt{5}}{2})^n$ Feb20 revised How to calculate $\exp(-x)$ using Taylor series significant typo