meta user
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| bio | website | |
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| location | ||
| age | ||
| visits | member for | 9 months |
| seen | 1 hour ago | |
| stats | profile views | 273 |
I'm an undergraduate student of mathematics in Germany, currently working on my bachelor thesis.
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May 18 |
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A “simple” 3rd grade problem…or is it? This question really doesn’t deserve nearly as much attention as it gets. Of course, the teacher’s mistake is outrageous and it’s fun to laugh at their incompetence, feeling superior to them, but c’mon. |
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May 15 |
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How discontinuous can a derivative be? Without math.stackexchange, I don’t think I’d ever have learned this, yet imagined it. This is such a great answer. Many, many thanks to you, Dave. (And also to you, @PeterTamaroff, as you linked this answer in your profile.) |
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May 15 |
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Does every smooth surjective function have a smooth right inverse? progress update |
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May 14 |
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Cantor set as a set of continued fractions? @FrankMcGovern I wouldn’t know, I can’t view it. But since you posted it, I’m positive it would help. : — D (It says I’ve reached the viewing limit, loosely translated.) |
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May 14 |
asked | Cantor set as a set of continued fractions? |
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May 14 |
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Can someone please explain $e$ in layman's term? Think of it as a pimped-up $2$. |
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May 14 |
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Does every smooth surjective function have a smooth right inverse? @GCD Nothing! I’ve forgotten about it. Thanks. But I’m also interested in a discussion of the conditions under which some left/right inverses might exist, so this doesn’t fully answer the question. |
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May 14 |
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How to evaluate $\int_1^\infty \frac{1}{x}-\frac{1}{x+1}~dx$ Look at the edited version! It’s $x+1$ instead of $x-1$. |
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May 14 |
revised |
Does every smooth surjective function have a smooth right inverse? mistake correction |
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May 14 |
revised |
Does every smooth surjective function have a smooth right inverse? made the question more structured, specific and readable |
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May 14 |
asked | Does every smooth surjective function have a smooth right inverse? |
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May 14 |
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Problem on multiplicative subsets 1 @rgl4 Yes, you could say that. The statement is true. |
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May 14 |
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Problem on multiplicative subsets 1 @rgl4 Well, yes. Exactly. Using the fact that $Γ$ is multiplicative: $$f(a_1 ·a_2) = \underbrace{f(a_1)}_{∈ Γ} · \underbrace{f(a_2)}_{∈ Γ} ∈ Γ$$ Therefore, $a_1·a_2 ∈ f^{-1}(Γ)$. So $Σ = f^{-1} (Γ)$ is multiplicative and will do the job for $f(f^{-1}(Γ)) = Γ$ because of the surjectivity of $f$. |
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May 14 |
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Problem on multiplicative subsets 1 @rgl4 Let $a_1, a_2 ∈ f^{-1}(Γ)$. What can you say about $f(a_1·a_2)$? |
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May 14 |
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Free online mathematical software And qtoctave adds a GUI similar to Matlab’s as far as I can tell. |
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May 14 |
answered | Problem on multiplicative subsets 1 |
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May 13 |
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Drawing an arc between two points Maybe this can help you. In your case, $θ = \arccos \big(\tfrac{a}{\sqrt{a^2 + b^2}}\big)$ gives you the angle $θ$ of the point $(a,b)$ to the (right ray of the) horizontal axis. |
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May 13 |
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show that holomorpic function f such that f(1/2n) = f(1/2n+1) are constant How does this answer help with the actual problem? |
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May 13 |
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Drawing an arc between two points You mention $x$ and $y$ coordinates as well as a width, a height, an startAngle an arcAngle and a type as input. What do they represent? And what is the angle between two points $A$ and $B$? Do you mean “with respect to the origin”, i.e. you draw a line through $A$ and the origin $(0,0)$ and a line through $B$ and the origin and that’s the angle? |
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May 12 |
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Imagining four or higher dimensions and the difference to imagining three dimensions @D.W.: Yeah, see the link to the mathoverflow question I included. |
