xkcd

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I wouldn't call a 10% difference negligible, but YMMV. But do I agree that 25 microseconds is negligible. The relative speed difference of the two methods depends on the speed of the computation inside the list comp / gen exp: if that computation is slow it may dominate the total time, hiding the di...

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How about 4π² AU³/yr² ?

But what's a minor constant of proportionality between friends?

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One problem with Runge–Kutta methods is that they don't conserve energy, and that could be killing your filaments. Try using a symplectic integrator like Verlet, or Leapfrog . I generally use the synchronized version of Leapfrog (for doing simple orbit sims) but the standard version's probably adequ...

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A minor correction: G is normally called the gravitational constant ; the term "gravitational parameter" or standard gravitational parameter normally denotes the product GM. In celestial mechanics, the standard gravitational parameter μ of a celestial body is the product of the gravitation...

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ETA: yep, it's perfect. Thanks! No worries. When you're done, it'd be great if you could let us know what you think of svg_stack. OTOH, since your SVG files are all nearly identical it probably wouldn't be too hard to write a bit of Python to do the tiling yourself, assuming that the files were bui...

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I have a large amount of SVG files (all nearly identical) which I want to put on a single page in a simple rectangular tiled layout. I assume you want to tile all these files into a single SVG file, rather than into a HTML / XHTML Web page. If so, svg_stack may be helpful. svg_stack combines multip...

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I wasn't aware that list comps create their own scope, now. Lots of people have been bitten by the "scope-leaking" of Python 2 list comps. Most of us just learned to live with it, but enough people complained that it was changed for Python 3, even though it makes list comps slightly less ...

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@MostlyHarmless What they said. Generators (including generator expressions) run slightly slower than list comprehension and take more setup time, so list comprehensions will beat them for stuff like this unless you're processing ridiculously huge strings of digits. BTW, in general, don't use `chr` ...

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You could do a Death Star cake and if someone asks which moon it is your SO can reply
"That's no moon".

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FWIW, the Wikipedia article on the Fermat point (the point such that the total distance from the three vertices of the triangle to the point is the minimum possible) invokes without proof "the dogleg rule" which asserts that if a triangle and a polygon have one side in common and the rest ...

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As I've mentioned before, I'm rather fond of Cramer's Transactional Interpretation of quantum mechanics. Roughly speaking, Cramer postulates that the normal past-to-future causality is complemented by future-to-past causality, so when atom A emits a photon that's absorbed by atom B, the actual traje...

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Speaking of liquid conductors & motors, check out the mercury "motor" . It's not very practical, but it is rather cute. WRT Carbon: it conducts, but rather poorly. Try running an electric current through a stick of pencil lead and see what happens! True, but graphite is a great lubrica...

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Echo244 wrote:I think they're invasive in Australia, and a bit tricky to get rid of.

They are. Also, blackberries can harbour rabbits, another invasive species.

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Maybe something based on the inverse hyperbolic tangent?
Eg y = ln((7-x)/(x-1))/2

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Some previous threads related to this topic:

Human settlement on mars? what do you think?
Designing a (Totally) self sufficient Mars colony

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There's a little bit of info at Insect flight obeys aerodynamic rules, Cornell physicist proves . As Neil said, at the small scale of typical insect wings & bodies air viscosity is much more significant than it is for typical birds & fixed-wing aircraft. In fact, when researches test large s...

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"There are only two hard problems in computer science: cache coherence, naming things, and off-by-one errors." Sig'd. :) To whom may I attribute this quote? According to http://skeptics.stackexchange.com/questions/19836/has-phil-karlton-ever-said-there-are-only-two-hard-things-in-computer...

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hotaru wrote:
Code: Select all
factorial = product . enumFromTo 1 isPrime n = factorial (n - 1) `mod` n == n - 1

<voice="Tom Hanks">Wilson!</voice>

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Is there an algorithm generating combinations C(n,k) such as the ouput order has this property : each k-uplet shares exactly (k-1) elements with its 2 neighbours. Yes, there is. It's Algorithm 452: enumerating combinations of m out of n objects by C. N. Liu and D. T. Tang. Here's an implementation ...

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FWIW, here are some StackOverflow links related to bit counting in various languages. Java: Optimizing Long.bitCount C: How to count the number of set bits in a 32-bit integer? Python: fast way of counting bits in python . As that page mentions you can do a fast popcount in Python, even on long inte...

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But yeah, if you just renamed the 12 hour as 0, then the system would make a lot more sense... ticking over from 11:59:59 am to 0:00:00 pm. That's how I remember which is which: 12 should really be 0, but we call it 12 because it's a carry-over from Ancient Times, before zero was invented. For bonu...

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It's not just DST and distance from your time zone's central meridian that affects the time of true noon (aka apparent noon) i.e., the time when the Sun is highest in the sky that day, when the length of the shadow of a vertical pole is at its minimum for that day. The average time period from one t...

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lengthMustBeBetween3and30Chars wrote:humans are the apex predator on planet Earth

[citation needed ]

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Nice work, phlip!

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I'm sure there are quite a few more, but your mention of the Weaire-Phelan structure reminded me of:

Aperiodic tilings, eg the Penrose tilings.
The various tessellations discovered by amateur mathematician Marjorie Rice.

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TL; DR: The probability of winning in the original 6D6 game is a little over 0.52. The 1D1 and 2D2 games are trivial. 1D1 is an immediate win with probability 1, 2D2 is an immediate win with probability 0.5. The Markov chain analysis for 3 3-sided dice is easy enough to do. There are 3^3 = 27 possib...

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I doubt it. I suspect that any such derivation would correspond to performing calculus by stealth, i.e., doing essentially the same things as what you'd do using calculus. Plenty of people before Leibniz and Newton played around with various infinite geometrical constructions and infinite series. As...

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I'm trying to imagine a fictional planetary system with multiple life bearing planets and moons. Due to some constraints travel and communication between these planets would only be possible when the planets are closest to each other. [...] What I'm thinking of is a system where one planet has inte...

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Not relativity question, but not big enough for a new thread: Am I right in thinking that spin doesn't change through an interaction? I can't really find anything to explain this or give an answer either way. I know that spin behaves in a few ways like a quantum analog to angular momentum, and I kn...

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I guess it's a little late now, but for future reference adwcleaner may be able to find & remove stuff that MBAM misses.

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In SR, all observers agree on the spacetime interval between events, s^2=(Δx)^2+(Δy)^2+(Δz)^2-(cΔt)^2. What they may disagree on is how much of that separation is spacelike, Δ r = sqrt((Δx)^2+(Δy)^2+(Δz)^2), and how much is timelike, Δt. But if s^2 is positive, all observers agree that it's positiv...

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(Veering off-topic) Several years ago I tried "inventing" a variant on noughts-and-crosses, played in four dimensions. From (hazy) memory it had a 3x3 grid of the usual 3x3 grid, so "lines" could be completed horizontally, vertically or diagonally on a single grid, by using the ...

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Firstly, the Maxwell-Boltzmann distribution doesn't apply to a liquid. It describes the energy distribution in an ideal gas where the gas particles do not interact with each other, apart from transferring kinetic energy via collision. But it doesn't work so well when the particles have other interac...

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I don't have any real Lego, but I've created some basic virtual Lego bricks in POV-Ray. A single brick: http://i2.photobucket.com/albums/y43/PM2Ring/LegoG2_zps5def69d5.png A base plate with a few blocks: http://i2.photobucket.com/albums/y43/PM2Ring/LegoH0_zpsf5fb881e.png I suppose I should do more w...

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Please don't meddle with pi. FWIW, I've read a couple of stories that did that and it annoyed the hell out of me. As others have said, pi is defined in terms of an ideal Euclidean circle, so it's the same in any consistent conceivable universe, unless you can conceive of a consistent universe where...

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I guess you don't know about Stars and Bars.

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I've heard that this "conversion rate" thing and the idea of tipping between dimensions is a heuristic. Is this description of simply tilting a bit into the time axis of a 4-D graph actually physically accurate? Well, all physics is models, so what does it even mean to ask "is it rea...

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Saying that moving c changes things is a bit misleading. Only dimensionless constants are meaningful when it comes to things like distinguishing between universes. This includes things like the ratio of the proton-electron masses, things like the fine structure constant or even any quantity express...

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It's complicated. They're certainly independent in Newton and cannot be proven not to be in SR. SR does distinguish between spacelike and timelike intervals which are separated by the lightcone but the angle of this cone (which depends solely on the speed of light) is arbitrary. Whilst geometricall...

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I was idly wondering today if there might be a relationship between the mass of the universe and C (nice if there was, since we could then calculate with certainty what that mass is). (BTW, lightspeed should be written with a small "c", but you can italicise it if you wish). The large-sca...

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