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| bio | website | |
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| visits | member for | 1 year, 2 months |
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| stats | profile views | 237 |
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Jan 21 |
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Filter signal through convolution @Kristian: Oh, then perhaps you haven't reached this yet, but convolution in the time domain is multiplication in the Fourier domain. So just take the Fourier transform of both, multiply, and detransform. |
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Jan 21 |
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Filter signal through convolution Why don't you use fourier analysis? You correctly tagged it as such. |
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Jan 20 |
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Solution of integration of $e^{x^2}$ @MårtenW: I must admit I missed that, but of course this can be solved by some appropriate complex substitution. |
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Jan 20 |
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Solution of integration of $e^{x^2}$ By "elementary", we mean "elementary functions", such as taking powers and multiplying and addition. There is no expression for the integral $e^{x^2}$. We can only give it a name (specfically the "error function"). I don't know how one can prove this. |
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Jan 15 |
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Is $f = x^2$ or only $f(x) = x^2$ correct? if, by $x$, the /variable/ is meant, then I do not see how that would be incorrect. You are right however, that (in words) "plugging in a value" produces a new "value". |
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Jan 15 |
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Is $f = x^2$ or only $f(x) = x^2$ correct? So why is your view correct? Under my view, the notation is correct (albeit confusing, since I am leaving away all the isomorphisms), but under your view, it is not. |
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Jan 15 |
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Is $f = x^2$ or only $f(x) = x^2$ correct? Not quite - $x$ is not some value, but instead a variable. In that case, $x^2$ can be seen as an element of $\mathbb{R}[x]$, the ring of polynomials, which is isomorphic to a subset of the ring of continuous functions. |
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Jan 8 |
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Mathematics, Philosophy and writing. Perhaps more famous for his literature than his mathematics: Charles Dodgson / Lewis Caroll. |
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Jan 5 |
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Learning category theory before abstract algebra I think categories inherently have group-like properties, so I'd suggest you learn abstract algebra first. Though strictly speaking, neither relies on the other, so you can give it a shot. |
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Jan 5 |
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In a ring homomorphism we always have $f(1)=1$? Could you add a word on why we want to rule out such mappings? |
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Jan 2 |
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a problem on the topological properties of a annulus Please fix ambiguous terminology: to say a map is open or closed usually refers to its graph having such properties. |
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Jan 2 |
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Are there real-life relations which are symmetric and reflexive but not transitive? Surely this relation is not reflexive for newborns... |
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Dec 29 |
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How to prove that something is definable or not definable in a given structure?! Dear André, I am currently doing a little undergraduate research project in o-minimal structures. Thank you for showing me that this is actually something more people know about :P |
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Dec 28 |
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A challenge by R. P. Feynman: give counter-intuitive theorems that can be translated into everyday language This theorem would fail Feynman's judgement for the same reason that Banach-Tarski is not an example. |
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Dec 27 |
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Consider the sequence 01110100… Induction?[filler] |
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Dec 26 |
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The cardinality of $\mathbb{R}/\mathbb Q$ Awesome.[filler] |
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Dec 26 |
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The cardinality of $\mathbb{R}/\mathbb Q$ So why exactly are they both size continuum? |
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Dec 25 |
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Rouche's theorem So... what did you try? |
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Dec 24 |
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Studying Math, All Over Again With all due respect, Khan is not mathematics. Khan is a list of courses in passing exams. |
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Dec 23 |
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Finding $\lim_{x\to \pm\infty}f(x)$ where $a,b>0$ It's bounded from above by $(a+b)/2$ |
