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| bio | website | about:blank |
|---|---|---|
| location | Berlin, Germany | |
| age | 18 | |
| visits | member for | 2 years, 4 months |
| seen | 5 hours ago | |
| stats | profile views | 229 |
I'm a highschool student from Germany interested in functional programming, especially Haskell.
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Aug 29 |
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Reducing the time to calculate Collatz sequences @Qiachu But then, I would need to save all that information. Assume, that I want to test all $n$ in the intervall $[1,1\,000\,000\,000]$ - I would need about 1 GiB just for caching! But otherwise, a good idea. |
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Aug 8 |
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How many real roots are there to $2^x=x^2$? @Arturo Err, that would make it clearer, but the time for editing is up. |
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Aug 8 |
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How many real roots are there to $2^x=x^2$? @Arturo This was meant because the answerer stated, that $x = 2, x = 4$ are the only solutions. |
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Aug 8 |
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How many real roots are there to $2^x=x^2$? Why is $x\approx-0.76666469596212309311$ a solution? |
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Jul 7 |
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Mathematical Career Advice to a young 16 year wannabe mathematician @sigma.z.1980 It's good to know, that other people have the same opinion as me. |
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Jun 15 |
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All functions $\frac{1}{f\left(y^2f(x)\right)} = \big(f(x)\big)^2\left(\frac{1}{f\left(x^2-y^2\right)} + \frac{2x^2}{f(y)}\right)$ @J. J. Ah, thanks. I didn't read the ${}^+$ in $\mathbb R^+$. |
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Jun 15 |
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All functions $\frac{1}{f\left(y^2f(x)\right)} = \big(f(x)\big)^2\left(\frac{1}{f\left(x^2-y^2\right)} + \frac{2x^2}{f(y)}\right)$ I just spotted a possible mistake: $1/f(0)=f(0)$ does not implies $f(0)=1$. It only implies, that $f(0)\in\{-1,1\}$. |
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Jun 14 |
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Is such a cryptographic system possible? That's a great article! |
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Jun 14 |
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How to solve this recurrence using generating functions? @muffel IIRC it's written by Graham, Patashnik and Knuth. |
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Jun 13 |
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How to solve this recurrence using generating functions? @muffel Concrete Mathematics is an awesom book when it comes to sums and generating functions. Just if you're curios. |
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Jun 13 |
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How to solve this recurrence using generating functions? @muffel For b) and c) recall that $\sum_{i=0}^ni^2=n(n+1)(2n+1)/6$. |
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Jun 13 |
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Expected value for a random variable Oh, yes. You're right. |
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May 28 |
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Convert any number to positive. How? In textbooks, the first one is often written $\lvert x\rvert$. |
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May 24 |
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A question on logic - where intuition can fail @amWhy: Thanks for finding such a good title. |
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May 24 |
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Modulo operation notation I would write it exactly like you, but add brackets. So $p(x) = (d(x) + b(x)\bmod w(x))$ but $p(x)\not=d(x)+b(x)\mod w(x)$. Notice also, that the spacing is also different. |
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May 24 |
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How to understand and appreciate the prime number industry? @Sebastien: I would not trust a prime I bought. It could be, that the vendor also sold it to someone else. |
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May 22 |
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Partial sum of ${A \choose i} {B\choose n-i}$, when $B=-1$? The formula holds for all integer $i$. (According to Knuth in Concrete Mathematics) |
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May 21 |
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How to prove that $\lim\limits_{x \to 0 }\;x^{-a}e^{\frac{-1}{x^{2}}} =0$ for all a? Why is it undefined? Then we have $\lim_{x\to0^-}{\sqrt x}/{\exp x^{-2}} = \lim_{x\to0^-}i\sqrt{|x|}/{\exp x^{-2}}$ which is the same except for an additional $i$. (Am I wrong?) |
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May 21 |
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How to prove that $\lim\limits_{x \to 0 }\;x^{-a}e^{\frac{-1}{x^{2}}} =0$ for all a? @Bill Dubuque: I am not very good at limits (I am still in highschool, they will teach these things next year). To prove that, I just sad, that $a\ln y$ grows slower than $y^2$ and thus $a\ln y - y^2\to-\infty$ as $y\to\infty$. I guess that's not a good solution. |
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May 21 |
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How to prove that $\lim\limits_{x \to 0 }\;x^{-a}e^{\frac{-1}{x^{2}}} =0$ for all a? @Bill: Quite similar to what you did. But I arrived at $\lim\limits_{y\to\infty}a\ln y - y^2=-\infty$... Maybe I calculated wrong. |
