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| bio | website | |
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| location | ||
| age | ||
| visits | member for | 2 years, 4 months |
| seen | 23 mins ago | |
| stats | profile views | 461 |
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Jul 5 |
comment |
Quantization of angular momentum: is Dirac's proof wrong? With step 2 as written (and BTW it would be easier to follow without overloading $j$ - it was the first element of the ket earlier, and now it's the second), isn't the existence of the eigenket $\lvert \beta, j\rangle$ true by definition of $j$ as "the maximum allowable value of $m$ for fixed $\beta$"? |
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Jul 4 |
comment |
Seeking formula for a custom game mechanic Ross' answer gives the exact solution if you let the time step tend to 0. The advantage of using an exact solution is that you can vary your time step without affecting the results (modulo rounding errors on the order of a couple of ULP). However, if you want to complicate the equations by going to solid bodies, handling collisions, etc. then incremental calculation with fixed time step is likely to be more straightforward. There's a separate gamedev.stackexchange.com where you'll find plenty of questions and answers about building physics engines. |
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Jun 29 |
comment |
Does this ratio converge to the Golden Ratio? It may be a useful observation (provable by induction) that each column becomes constant $(k-1)!$ after a triangular-number $k(k-1)/2$ of smaller values. |
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Jun 27 |
comment |
Getting the max/min longitude/latitude within a distance from a point @sandis, the best approach probably depends on your restrictions on d and plausible latitudes, but it's really a data structures question rather than a mathematical one. A relatively simple approach would be to use oct-trees; for more sophisticated approaches look at papers from the GIS community or search for terms like k-nearest. |
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Jun 27 |
answered | Getting the max/min longitude/latitude within a distance from a point |
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Jun 14 |
comment |
Bat and ball calculations Perhaps a more pertinent question is "Why would you work it out in MS Excel?" |
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Jun 9 |
awarded | Civic Duty |
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Jun 8 |
awarded | Constituent |
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Jun 8 |
awarded | Caucus |
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Jun 7 |
comment |
Find the remainder when $ 12!^{14!} +1 $ is divided by $13$ Note that the original problem can also be solved by Fermat's little theorem: $12!^{12} \equiv 1 \pmod{13}$. |
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Jun 6 |
comment |
Finding a grammar for a formal language Do you realise that this language is just [ab]*? |
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May 28 |
answered | graph-theory task |
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May 21 |
comment |
Change of coordinate system on a sphere $L \times O$ is intended to be a cross product in the Euclidean embedding, i.e. one of the two poles of which $LO$ is (part of) the polar. The descriptions of $LP'$ and $PP'$ are intended to clarify what you mean by local lat and long. $LO$ and $NP$ cannot possibly be parallel, because on the surface of a sphere two lines are parallel only if they are collinear, and $N$ is not on $LO$ by construction. |
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May 21 |
comment |
Why do the Fibonacci numbers recycle these formulas? Putting the last row into the OEIS search turns up some sequences with a few references. They would be a good place to start looking for an answer. |
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May 19 |
comment |
Change of coordinate system on a sphere To clarify what you know: let $L$ be the local origin, $O$ be the true origin; $N$ be the "North Pole" of the local coordinate system (i.e. $L\times O$ normalised); let $P'$ be the intersection of $LO$ with $NP$; you know the lat and long of $L$ in the global system, the (signed) distance $LP'$= local longitude, and the (signed) distance $PP'$= local latitude? |
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May 18 |
answered | The game Officers |
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May 18 |
comment |
Cryptography puzzle Just a thought, but the numbers on the left are Unix timestamps from yesterday and today. |
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May 16 |
revised |
Truth table reduction Link to definition of term |
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May 15 |
comment |
Complex roots of $z^3 + \bar{z} = 0$ You only find 3 solutions, but you haven't explained why you're discarding two (x, y) pairs. |
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May 15 |
comment |
Is it wrong to tell children that 1/0 = NaN is incorrect, and should be ∞? I don't get it. What's "English" about a temperature scale invented by a German who was born in Poland and lived in the Netherlands? |
