Creating a raster mosaic from multiple un-referenced jpegs

Question: I have multiple historical aerial photographs that I would like to use to compare coastal change over time in relation to urban development. The aerials I have obtained come in tiles that are not georeferenced but they are also not big enough to get a good RMSE when georeferencing them individually. So to fix this I would like to turn each of the individual tiles into one large mosaic to use for georeferencing. However, when adding them into Arcmap they each just layer on top of each other which does not help me at all. Is there anyway that I can manually (or otherwise) arrange them into their correct order so that I can then combine them into a single mosaic and subsequently accurately georeference?
Comment: Use something like GIMP or Photoshop to create a single image from the individual images, then bring that result into ArcGIS for georeferencing.  Still, I don't think this will fix your RMSE issue.  I suspect that many of your images look like orthos but are really obliques.  Garbage in, garbage out.
Answer: You can use Photomerge if you have overlap in your rasters.

Images should overlap by approximately 40%. If the overlap is less, Photomerge may not be able to automatically assemble the panorama. However, keep in mind that the images shouldn't overlap too much. If images overlap by 70% or more, Photomerge may not be able to blend the images.

If Photomerge does not work for you, try a manual overlap/blend/stitch.
After this you can simply georeference the raster. Use an online service, find good points for the corners and add extra points for the coastal area for an increase in precision in that area.


How to load css files in a specific order

Question: I'm wondering if someone can help me with this. The theme I am working on has a custom theme options page where you can select various colors for the website. The problem is that the stylesheet it produces loads before the bootstrap and main stylesheet in header.php. I need this to load after those two. Is this possible to do?
Comment: Have you read about [stylesheet dependencies](http://wordpress.stackexchange.com/questions/96161/how-to-enqueue-style-before-style-css) ([another explanation](http://wordpress.stackexchange.com/a/99468/73))?
Comment: Doesn't work for me. I think it's because the various color stylesheets are being enqueued from my theme-options.php file instead of the functions.php file.
Answer: Found a solution. I just added a number at the end like this..
add_action( 'wp_enqueue_scripts', 'moana_enqueue_color_scheme', 789 );
Comment: That'll work too, as that *number* is actually the priority in which the callbacks are rendered in an action hook. But, you'll need to create separate callbacks for each of your stylesheets and use priorities accordingly. The best way is using the stylesheet dependencies, which gives you much more control over the enqueued scripts and stylesheets.


Programming as a conversation

Question: I have often wondered if it would be possible to write a programming language that would work as a conversation. I would tell the computer that I want to store coordinates and it would ask what representation I would use. I would then ask to find the shortest path between points and it would ask if I want to use Djkstra's, brute force or use Floyd's? What research has been done towards producing a system like this?
Comment: Even if you could, could you imagine the conversations... User: "Computer, sort this list using bogosort". Computer: "Here I am, brain the size of a planet, and he asks me to use bogosort...". User: "What's wrong with bogosort?". Computer: "I'd make a suggestion, but you wouldn't listen...". Then again tech support might be fun, you could try to talk manically depressed computers out of electronic suicide.
Comment: Person: "Erm yeah, i want this program to.. umm.. not sure how to say this.. you know what i mean, right?" Computer: "wtf?"
Comment: It sounds strangely like the conversation between a product manager and a developer
Comment: You do realize that every language since Assembly, C, and C++ have tried to make it as conversational as possible? I'd say the only thing that would come close is ASP.NET since there are no brackets *shutters
Comment: Well, it's possible to write a program as a [Shakespearean dialog](http://shakespearelang.sourceforge.net/report/shakespeare/). The sky's the limit.
Comment: @TheLQ: In a conversation you'd describe everything on a general level then go more specific
Answer: I think such a language would need an artificial intelligence in place, or at least a system that can learn.
The problem is that humans don't know what they want.
Also, even writing in classical imperative language we still make logical errors. Imagine trying telling a non-intelligent software what he has to do.
Comment: @Moshe: No, they know exactly what they **want**, it just happens to be almost entirely unlike what they **need**.
Comment: Humans don't know what they want. +1
Comment: @Joe D - True, true.
Comment: This happened to a friend of mine all the time (and myself too). "Dammit!" "What?" "The computer did exactly what I said"
Answer: What you're describing sounds less like programming and more like using an application.
Some problems you'd have to address in such a system:

Repeatable results.  The current source-code paradigm stores a list of instructions for the computer- in your 2-sided conversation, do you only store 1 half of the conversation?  If so, that's not really any different from what we have.  If you store both halves of the conversation, how would you go back and change things without disrupting the whole flow of the conversation thereafter?
Who decides what the computer can respond with- eg, what if you want to use shortest-path algorithm that hasn't been pre-coded for you to select?
How are you going to map this conversation onto the low-level language a computer really uses (which is still a sequential list of instructions)?
Comment: Good points. This is most certainly, not an easy task
Answer: Prolog comes close except for two things:

It doesn't ask you how to store data, it just stores it.
It won't suggest you what to do in an intelligent way.

But it does have the behavior to store facts and have rules to verify them or generate a result with it.
Answer: Intellisense/CodeAssist feature in modern IDEs come to mind as the closest thing in current software practice to your requirements... whereby you discover the capabilities of the system as you type in code. It allows you to navigate the feature-space of the development platform in real time. Its not exactly the same as you describe but comes pleasantly close enough.

Programming as a conversation


Effect of keys on modern performances

Question: I understand that traditionally, certain "moods" are associated with certain keys.  I further understand that this is mainly due to the way keyboards were tuned during the classical era, but that now, keyboards are "equally tuned" so that the only difference between major keys is the pitch. (same with minor keys).  That being understood, are we missing something in the modern performances of classical pieces that were originally written, and I assume, meant to be performed in their "unequally tuned" keys?
Comment: Related: http://music.stackexchange.com/questions/12573/why-do-musicians-prefer-to-play-in-certain-keys?rq=1
Comment: For people with any amount of perfect pitch, they can hear differences (to a greater or lesser extent) between keys that use the same scale but are based on different pitches. Aside from that, I think the answer to the question linked in my first comment is a good one.
Comment: There is no reason *not* to perform music with a historically correct tuning (and at the historically correct pitch, which can make a big difference to vocal music) if one wants to. Indeed, many performers do exactly that, at least as far as scholarly research can take them.
Answer: Some of the "mood" is cultural, e.g. certain Maqam are said to evoke feelings of a distant desert, which might be tricky if the audience has never even seen such, or for one who does not know that minor keys indicate sadness because their musical culture is based on rhythm, leaving classical works to sound much the same to them.
Answer: The "missing" in "Are we missing something?" implies a value judgment, so instead I'll just address some of the key differences between equal temperament and historical temperaments.
At least these things would be different:

Older tunings, meantone or tempered, generally had a set of keys where the important major thirds were just, or at least closer to it.  This affects the degree of consonance of chords (which are stacked 3rds.)
The tempered tunings generally have different sets of 5th intervals, e.g. the Werckmeister tunings, and thus, as an example, the root chords for different keys have different degrees of consonance.

That the different historical tunings result in different sounds is indisputable.  For careful listeners this difference is audible. It's arguable (and possibly subjective) about how these sonic differences affect the emotional/aesthetic impact of music for modern audiences.
This video has a nice demonstration of different tunings, albeit with some unfortunate audio glitches.
Comment: I appreciate the feedback, and the video link.  I don't mean to imply a "value judgment" when I asked the question.  I recently listened to a recording of Beethoven's great "Appassionata Sonata" and that really prompted my question.  I want to hear it as Beethoven intended it to be heard, and it dawned on my that I assume I am hearing it on an "equally tuned" piano.  Are there recordings of great piano pieces that are advertised as being performed on a piano tuned the way Beethoven's piano would have been tuned when he wrote the piece?
Answer: I don't think so, as instruments were tuned to sound good in one particular key. True, they didn't sound good in another key, due to the tuning vagaries, but in one key, it all worked. So, with 12et, now, we could play a piece in any key we wanted, and it would sound authentic, but what difference would that make?
Comment: There were several tunings in common use between about 1725 and 1900 which sound "good" (to modern ears) in all keys, but each key has an audibly different deviation from 12TET.

Effect of keys on modern performances


How to make docky and gnome shell work together?

Question: I like gnome shell and I like docky. The problem is that the gnome shell places the notifications and that little notification dock down there. I want to place docky at the bottom but then the notifications interfere with it. Is it possible to move (off possible) everything related to the no fixations to the panel and/or the top right? Thanks
Answer: I use the Left/Middle-message-tray Gnome shell extension to get the notification area out of the way.


Access to Stellar Expert Market Pair

Question: I am new to Stellar and I had a question whether the marker pairs on Stellar Expert are public for general consumption, or are many of these private connections? https://stellar.expert/explorer/public/market?type=fiat
Answer: Anyone can add offers to the Stellar network. Once there is a valid buy and sell offer the Stellar Network will complete the transaction automatically.
So to answer your question, they are public for general consumption.

Access to Stellar Expert Market Pair


What factors could lower the voltage of a galvanic cell

Question: Recently I conducted a lab in which the voltage of a galvanic cell between two metals was recorded. Both metals were placed in an solution of their own ions with nitrate and a salt bridge was made by dipping some paper in salt water. The only issue is the voltage recorded in the cell was lower than that calculated using standard reduction and oxidation potentials. Does anyone have any ideas as to why this might be? I known the metals were not super clean although I don't think that would have an affect on the voltage.
Answer: Although it seems simple to make a galvanic cell ( i.e. a battery) it is really fairly complex.

The theoretical voltage is given by the Nernst equation.
The actual measured voltage also depends on the current. The equation
$V=iR$ still applies. So various restance sources in the cell cause voltage drops.

The current must be very low so a high impedance voltmeter must be    used. (Not really a problem these days with modern semiconductor
    voltmeters as opposed to galvanometers.)
The salt bridge offers resistance, so it has a voltage drop.
Impure metals for the anode or cathode can cause a voltage change.
Surface coating can cause a voltage drop.
The acid or base concentration can cause a voltage change.
The ionic strength of the solution can change the voltage.
Answer: There are more factors to consider when determining the true voltage of the cell such as the development of overpotentials.
'In electrochemistry,  overpotential is the potential difference (voltage) between a half reactions thermodynamically determined reduction potential and the potential at which the redox event is experimentally observed.
In a galvanic cell overpotential means less energy is recovered than thermodynamics predicts. This extra/missing energy is lost as heat.
Overpotential is specific to each cell design and varies across cells and operational conditions, even for the same reaction.
Regarding the galvanic cell, two possible polarities of overpotential can occur:

the anode may be less negative, supplying less energy than thermodynamically possible.
the cathode is less positive, supplying less energy than thermodynamically possible.

The overpotential increases with growing 'current density', or rate as described by the 'Tafel equation'. Each step of the electrochemical reaction is associated with multiple forms of overpotential. The overall overpotential is the summation of many individual losses.
'Voltage efficiency' describes the fraction of energy lost through overpotential. For a galvanic cell it is the ratio of a cells experimental potential divided by the cells thermodynamic potential converted to a percentile.
Overpotentials can be grouped into three categories, activation, concentration and resistance but  can be divided into many different sub categories also that are not well defined, such as 'polarization overpotential'.'
Ref:overpotential/wikipedia
For more information on 'voltage efficency','Tafel equation','current density' I suggest to 'Google' them or to look at the page I have referenced.
Other factors such as loss of electrolyte and the temperature of the system can also cause loss of voltage.


Will loose handlebars result in slower riding?

Question: I went for a ride this morning and my handlebars were loose. I now realize that it is unsafe to ride like that but my average speed was dramatically lower. Do you think it is because of my loose handlebars?
Comment: I would imagine that if you know your handlebar is loose you will not place as much force on it and hence will not cycle as fast.
Comment: It would certainly slow you down if you had hit even the tiniest bump or had to make any sudden manoeuvres - it's hard to go quickly when laying on the road asking what the hell just happened to your handlebars! ;) Always make sure to do some quick checks (brakes, steering, tyre pressure...http://bicycles.stackexchange.com/questions/2161/pre-ride-checks) of the bike before a ride
Answer: With loose handlebars, the primary thing which you should be worrying about is your face - its a great way to lead to a nasty crash. Don't ride with loose parts on your bike. Speed is the last thing you should be worrying about.
You likely went slower due to less control of the bike with loose handlebars making your brain hold you back on speed. Other factors such as environment or tired-ness may have come into play, but loose handlebars would make most people ride slowly and carefully [or better yet, walk the bike], avoiding any bumps until they could tighten down the handlebars if they weren't carrying the appropriate tools with them.
When you're riding intensely, you actually end up pulling up on your handlebars, which you can't do with loose handlebars so you can't ride as hard, so you can lose speed at the top end with loose handlebars.


Using ham radio bands for telemetry

Question: If I built a machine that went far away, say a buoy, would I be allowed to use ham radio frequencies to transmit telemetry data back to its base station, if I used my call sign? This is for personal research, not commercial applications.
Answer: I don't see why not as long as you followed the regulations for ID and transmission mode.  There are beacons, satellites, balloons and more transmitting telemetry.  Beyond the laws I would recommend following the band plans for where to transmit and pay attention to where the signals from your buoy would reach.  For example, the lower end of the 70cm band isn't part of the allowed spectrum in Canada so when I go much farther North I have to pay attention and not transmit on some frequencies I can use in the US.
Answer: Make sure you follow the regulations on 'unattended operation'.
And if you are going to be floating a buoy into the sea, be aware that you may end up transmitting from the territory of another country, at which point your transmission could well be very illegal. If you ended up floating a 'message in a bottle' beacon that made its way to North Korean waters, for example, you could create an international incident!
Answer: I would say that it is probably legal, but depending on the country in which you operate it, there might be restrictions on unattended transmitters. In Switzerland, for example, only amateur radio clubs (and not "private" operators) are allowed to operate an unattended station (e.g., repeater, beacon, etc.) -- if you're member of a club, and the club is ok with that, then no problem (but of course the station has to identify itself with the club's callsign). So, although it is probably legal, you should check if there are any specific restrictions on operating unattended stations in your country.

Using ham radio bands for telemetry


How to find path for the mazes in Metal Gear (NES)?

Question: I just played through Metal Gear (NES) again for the first time in ~23 years. A good game. What I don't understand though, is that it seems as though we HAVE to go through the mazes in the game in order to complete it and I can't remember finding any information ingame on how to get through them. Is that correct? We HAVE TO go through the mazes AND there is no ingame information about the correct path? Just... trial and error?
Comment: Perhaps look for an informative let's play or walkthrough? They will probably give such details. :)
Comment: @Miguel Oh, I did, and I am done with the game. I am interested in finding out if the information I am looking for can be found in-game or if it came down to old brute force trying.
Comment: I think what miguel was getting at. Was to look online for someone that did a comprehensive "lets play" video. Or a walkthrough video. Wherein, they likely touch on the info you are looking for.
Answer: There was no answer in the game for how to solve this maze. This was confirmed by someone in 2009 who dumped all of the text from all of the transceiver messages just to try to answer this exact question. The original Metal Gear on the MSX didn't include these mazes and they seemed to be added to the NES version without any additional clues. However this maze like the one in Zelda (which did have an in game hint) weren't incredibly difficult to solve through  trial and error. At the time I remember trading hints with other kids at video rental stores and at school to get through this. Swapping  through all 8 cards seemed more of an annoyance with this game.
I think the majority of people who couldn't figure this out and didn't call into the Nintendo Power Line (which activated just in time for this release) used Nintendo Power Issue #3 where this question was asked in the Counselor's Corner. You either subscribed to Nintendo Power then or had friends who did back then. The exact question in this issue was "How do I get through the maze zones" with a detailed answer.
This issue came out in November 1988 after Metal Gear released in June 1988 in North America. So it was just in time for kids who had either given up or were just about to get this game for the holidays to not get stuck on this.
Comment: Awesome answer. Thanks a lot! Was just as I suspected then, since, back in the good old days it wasn't uncommon for games to have "design flaws", both intentional as well as unintentional. I do remember trading game info / secrets with friends. Good times.
Comment: The reason the MSX/PS2/PS3/Xbox 360 version didn't have these mazes is because there were no buildings 4 and 5... instead they were the basements of buildings 1 and 2.
Comment: Yeah, it was a long time ago, but a friend of mine had Metal Gear and beat it before me. I do remember reading this Nintendo Power as a kid. Without Nintendo Power and the Power Line (I remember calling at least twice for Strider before my parents got on my case) I don't think I'd have finished any games! ;)


Illusions within the Cthulhu Mythos

Question: could anyone please advise me of any beings, within the Cthulhu Mythos, that use any form of illusionary spells. Specifically I'm trying to determine if any are known to use their magic, almost like a glamour, to lure or ensnare.
Comment: Mind control seems to be possible even in HPL's own stories. Dreams in the Witch House  (title?) describes this. But an actual visual illusion, I don't think there were ever any of those. When someone described Ryleh, the bizarre geometry wasn't an illusion, but a human's visual cortex trying to interpret very real extra-dimensional locations/angles. Maybe Derleth had something more akin to magic spells, I don't really read his crap.
Comment: Mind transference has cropped in a couple of recent questions on HPL.  Many of the Old Ones have some kind of influence over the minds of men in one way or another, but like the rest I'm not sure how much of it qualifies as illusionary.  Mostly it just drives you insane.
Answer: Nyarlathotep takes many different forms, both in Lovecraft's stories and in "Cthulhu Mythos" stories by other authors, see the table here. Not sure if he could be said to illusions to "ensnare", although in Lovecraft's original Nyarlathotep prose poem where the character first appeared, everyone seems strangely drawn to public exhibitions he would give, which seemed to involve mysterious hypnotic imagery as seen in the section below:

I remember when Nyarlathotep came to my city—the great, the old, the
  terrible city of unnumbered crimes. My friend had told me of him, and
  of the impelling fascination and allurement of his revelations, and I
  burned with eagerness to explore his uttermost mysteries. My friend
  said they were horrible and impressive beyond my most fevered
  imaginings; that what was thrown on a screen in the darkened room
  prophesied things none but Nyarlathotep dared prophesy, and that in
  the sputter of his sparks there was taken from men that which had
  never been taken before yet which shewed only in the eyes. And I heard
  it hinted abroad that those who knew Nyarlathotep looked on sights
  which others saw not.
It was in the hot autumn that I went through the night with the
  restless crowds to see Nyarlathotep; through the stifling night and up
  the endless stairs into the choking room. And shadowed on a screen, I
  saw hooded forms amidst ruins, and yellow evil faces peering from
  behind fallen monuments. And I saw the world battling against
  blackness; against the waves of destruction from ultimate space;
  whirling, churning; struggling around the dimming, cooling sun.
Comment: Nyarlathotep is a good angle, he's also described as taking different forms and names.  Again though, not sure if it is properly illusionary so much as other-worldly/dimension.
Answer: I think the "illusion magic" happens more in game adaptations than in the books themselves.
For example, in Cthulhu RPG, there was a spell called "Bait for humans":
Causes the image of a fabulously large and beautiful cut diamond to float in the air before the target.  The spell costs the caster 1 magic point per casting, lasts for five minutes, and can be repeated indefinitely.  Approximate range of the spell is one mile.  As a target approaches the illusion, the diamond recedes at approximately the same speed, in the direction the caster wills, presumably to where the hungry cthonian waits.  As in sport fishing, the target decides whether or not to take the bait.  Only chthonians have this spell.
In Darkest Dungeon, there is the Siren:

Illusions within the Cthulhu Mythos


Evaluating $\int_{-\infty}^\infty \frac{1}{(4+x^2)^2}\mathrm dx $

Question: I wish to evaluate the integral $\int_{-\infty}^\infty  \frac{1}{(4+x^2)^2}\mathrm dx $. This is a complex analysis exercise so expecting that some sort of complex analysis technique is required, my first instinct was to split the integrand into partial fractions, making use of the fact that $(4+x^2)^2=(x+2i)^2(x-2i)^2$ but the Cauchy Integral Formula does not seem to work here so I got stuck. Then I went back to using substitution, say $x = \tan u$ but that didn't really work out as well, though I am not sure if I missed any technical details.
Comment: If you let $x=2\tan u$ then you will have to calculate an integral of $\cos^2u$. Just commenting, since you seem to have thought about such substitutions as well.
Answer: One way to simplify the approach is to use differentiation under the integral.  Then, note that
$$-\frac1{2a}\frac{d}{da}\int_{-\infty}^\infty\frac{1}{a^2+x^2}\,dx=\int_{-\infty}^\infty\frac{1}{(a^2+x^2)^2}\,dx\tag 1$$
The integral on the left-hand side of $(1)$ can be evaluate a number of ways.  Inasmuch as the OP seeks to use contour integration, we proceed as follows.
Let $C$ be the contour comprised of the real line segment from $-R$ to $R$ and the upper-half-plane semi-circle centered at $0$ with radius $R$.  Then, we have from the residue theorem for $R>a>0$
$$\begin{align}
\oint_C \frac{1}{z^2+a^2}\,dz&=\int_{-R}^R \frac{1}{x^2+a^2}\,dx+\int_0^\pi \frac{1}{(Re^{i\phi})^2+a^2}\,iRe^{Re^{i\phi}}\,d\phi \tag 2\\\\
&=2\pi i \text{Res}\left(\frac{1}{z^2+a^2},z=ia\right)\\\\
&=\frac{\pi }{a}
\end{align}$$
The second integral on the right-hand side of $(2)$ vanishes as $R\to \infty$.  Hence, we find that
$$\int_{-\infty}^\infty \frac{1}{x^2+a^2}\,dx=\frac\pi a \tag 3$$
Taking the derivative of $(3)$ with respect to $a$, multiplying by $-1/(2a)$ and setting $a=2$ yields the coveted result

$$\int_{-\infty}^\infty\frac{1}{(4+x^2)^2}\,dx=\frac\pi{16}$$
Comment: I noted that f(z) is an even function so I tried to calculate Res(f(z); 2i) directly by forming the partial fractions, thinking that multiplying the residue with 2πi would give me the final answer but it didn't work. Do you know why?
Comment: @homaniac That should have worked.  How did you determine the residue? The pole in the upper-half (and the one is the lower half-plane) is of second order.
Comment: Thanks for the feedback. Something went wrong with the way I split the partial fractions, my usual way of doing it got me stuck. Has that got something to do with it being of second order?
Comment: @homaniac If you would, show your decomposition into partial fractions.
Answer: An alternative solution through real-analytic tools. For any $\alpha>0$ we have
$$ I(\alpha) = \int_{-\infty}^{+\infty}\frac{1}{\alpha^2+x^2}\,dx =\frac{\pi}{\alpha} \tag{1} $$
and by differentiating both sides with respect to $\alpha$ we get:
$$ I'(\alpha) = -\int_{-\infty}^{+\infty}\frac{2\alpha}{(\alpha^2+x^2)^2}\,dx = -\frac{\pi}{\alpha^2}\tag{2} $$
hence by evaluating at $\alpha=2$ we get:
$$ \int_{-\infty}^{+\infty}\frac{dx}{(4+x^2)^2} = \left.\frac{\pi}{2\alpha^3}\right|_{\alpha=2}=\color{red}{\frac{\pi}{16}}.\tag{3}$$
Comment: I'm shocked.  Jack D'Aurizio takes the trivial way. ;-)).  I also used Differentiation under the integral, but evaluated the trivial integral using contour integration.
Answer: This is the standard approach to a problem like yours: Integrate over a semicircle with diameter along the real axis and center at $0$, using the residue theorem (or Cauchy's integral formula of you can). Let the radius go towards $\infty$, and argue that the contribution to the integral from the circle arc goes to $0$.
No partial fractions needed, although the factorisation is handy when locating and classifying poles.
Answer: Another alternative is to use Glaisher's theorem. If $f(x)$ is an even function with series expansion of the form:
$$f(x)= \sum_{k=0}^{\infty}(-1)^kc_k x^{2k}$$
and the integral over the real line converges, then we have:
$$\int_{-\infty}^{\infty}f(x) dx = \pi c_{-\frac{1}{2}}$$
where $c_{-\frac{1}{2}}$ is defined from an appropriate analytic expression of the series expansion coefficients, where factorials are supposed to be replaced by gamma functions. This can be made more rigorous, it's a special case of Ramanujan's master theorem. The advantage of this method is that you essentially have the same benefit as when doing complex analysis where the integral is derived from an appropriate series expansion coefficient, but you now don't have to bother about setting up appropriate contours. In fact, the theorem remains valid if contour integration won't work.
So, all we have to do is find an analytic expression for $c_k$. This is a simple matter of differentiating the geometric series. If we put $x^2 = y$, then we have:
$$\frac{1}{4+y} = \sum_{k=0}^{\infty}(-1)^k \frac{y^k}{4^{k+1}}$$
Taking minus the derivative w.r.t.$y$ yields:
$$\frac{1}{(4+y)^2} = -\sum_{k=1}^{\infty}(-1)^k k \frac{y^{k-1}}{4^{k+1}} =\sum_{k=0}^{\infty}(-1)^k (k+1) \frac{y^k}{4^{k+2}}  $$
So, we see that $c_k = \frac{k+1}{4^{k+2}}$ and we're now supposed to analytically continue this to real $k$ in the standard way allowing us to insert $k = -\frac{1}{2}$ in here, but in this case that's trivial. This yields $c_{-\frac{1}{2}}=\frac{1}{16}$, the integral is thus $\frac{\pi}{16}$.
Comment: I noted that f(z) is an even function so I tried to calculate Res(f(z); 2i) directly by forming the partial fractions, thinking that multiplying the residue with 2πi would give me the final answer but it didn't work. Do you know why?
Comment: @Homaniac That residue is $-\frac{i}{32}$, so you may have a mistake computing the partial fraction expansion. But note that you can compute the residue directly and in fact a fast way to get to a partial fraction expansion is by computing residues, or at least the Laurent expansions needed to compute residues.
Comment: I have 1/(x-2i)^2(x+2i)^2 = 1/8ix/(x-2i)^2 - 1/8ix/(x+2i)^2 and I got stuck here :(
Comment: @Homaniac Suppose $R(z)$ is a rational function that tends to zero at infinity, with poles at $z = z_j$. Then consider the singular parts of the expansions around each $z_j$, let's call these truncated expansions $S_j(z)$. Then the partial fraction expansion of $R(z)$ is $\sum_j S_j(z)$. You can see this by considering the function $f(z) = R(z) - \sum_j S_j(z)$. Then $f(z)$ is a rational function that tends to zero at infinity, but which has only removable singularities. So, $f(z)$ is a polynomial, but since it tends to zero at infinity, it is in fact identical to zero. So, let's try this.
Comment: We can simplify things in this case by considering $R(z) = \frac{1}{4 + z^2}$, and then square each expansion, we then need to consider the constant term as well, as that generates a singular term upon squaring. If we put $z = 2 i + t$ and expand in powers of $t$, we get: $$\frac{1}{4it + t^2} = \frac{1}{4it}\left(1+\frac{it}{4}+\mathcal{O}(t^2)\right)$$ Squaring this yields a singular part of $R^2(z)$ of $$-\frac{1}{16 t^2}-\frac{i}{32 t}$$
Comment: So, we see that the residue will be $-\frac{i}{32}$, but you can continue to find the singular part of the other expansion around $z = -2i$ as well. The first expansion in terms of $z$ yields $$S_1(z) = -\frac{1}{16(z-2i)^2}-\frac{i}{32(z-2i)}$$ The other expansion yields $$S_2(z) = -\frac{1}{16(z+2i)^2}+\frac{i}{32(z+2i)}$$


What is bootstrapping?

Question: I keep seeing "bootstrapping" mentioned in discussions of application development.  It seems both widespread and important, but I've yet to come across even a poor explanation of what bootstrapping actually is; rather, it seems as though everyone is just supposed to know what it means.  I don't, though.  Near as I can figure, it has something to do with initialization tasks required of an application upon launch, but I could be completely wrong about that.  Can anyone help me to understand this idea?
Comment: According to Wikipedia, there are four uses of the word "bootstrapping" with regards to computing - http://en.wikipedia.org/wiki/Bootstrapping#Computing
Comment: I just updated HeDinges post with this. I was looking for some clarification on what form of bootstrapping Alex was looking at.
Comment: In Software development it refers to the development of successively more complex, faster programming environments.
Comment: In .NET software development, my understanding is that it refers to the setup of the environment in which the application will run such as any services that need to be registered or loaded.
Comment: Im pretty convinced at this point that folks just enjoy the word and use it whenever they want to sound exciting when they really mean "set something up" or "initialize" something.
Answer: "Bootstrapping" comes from the term "pulling yourself up by your own bootstraps." That much you can get from Wikipedia.
In computing, a bootstrap loader is the first piece of code that runs when a machine starts, and is responsible for loading the rest of the operating system. In modern computers it's stored in ROM, but I recall the bootstrap process on the PDP-11, where you would poke bits via the front-panel switches to load a particular disk segment into memory, and then run it. Needless to say, the bootstrap loader is normally pretty small.
"Bootstrapping" is also used as a term for building a system using itself -- or more correctly, a predecessor version. For example, ANTLR version 3 is written using a parser developed in ANTLR version 2.
Comment: Correct me if I am wrong. Although this answer explains technical details of what bootstrapping can be, it never answered the original question within the context of the question.
Comment: @jayscript - How would you choose to answer this question? It's an idiomatic expression, and idioms are typically well-understood by the social group that uses them, and incomprehensible outside of it. I tried to answer by example, which I believe is one of the few ways to attempt to translate idiom.
Comment: Personally, I look at this question -- and the constant upvotes that I get for the answer -- as symptomatic of a bigger issue within the field of computer programming: a belief that there has to be a rational reason behind every term, every language feature, every design decision. The real world is a lot messier than that.
Comment: @kdgregory I wouldn't be able to answer this question as I came here to look for answers. I speculate that the word bootstrapping itself is a metaphor for several different technical concepts that are loosely related, which might be the source of confusion.
Comment: @jayscript - Sometimes a cigar is just a cigar.
Answer: An example of bootstrapping is in some web frameworks. You call index.php (the bootstrapper), and then it loads the frameworks helpers, models, configuration, and then loads the controller and passes off control to it.
As you can see, it's a simple file that starts a large process.
Comment: In terms of web development (which was the context of the original question), I think this is the best answer.
Comment: @Kallaste, fine, but this is the answer I came looking for, and, based on the context of the original question ("application development"), it seems to be the most appropriate answer as already pointed out.
Comment: @aaron.bynum, no, the answer given applies to web development frameworks, and definitely not application development. The answer is misleading and flawed, because it relies on a commonly held misunderstanding of what bootstrapping actually is and where it came from. It's just spreading misinformation. If that's what you came here looking for then fine, but SO as a whole values correct information. Thus my comment.
Comment: Seems pretty related to Laravel, but Laravel was still not there in 2009.
Comment: @Wajdan Ali No, this should not be the accepted answer. This is a microscopic view of a new use of the term bootstrapping, which some would argue is actually a misuse of a much earlier term. "To bootstrap" refers to pulling yourself up by your bootstraps, that is, to use the power of something to leverage itself. It is the origin of the term "to boot your computer." The current pop usage in web development is not the only (or the original) usage of the word. Many other answers address this appropriately.
Comment: FYI, if you want to know what bootstrapping really is, you can look at Ivan Poliakov's answer below. It's actual bootstrapping.
Comment: Best answer so far. And Not just that you answered it in the web development context, I acutally wanted to understand it from a framework and php perspective. Thank you
Answer: The term "bootstrapping" usually applies to a situation where a system depends on itself to start, sort of a chicken and egg problem.
For instance:

How do you compile a C compiler written in C?
How do you start an OS initialization process if you don't have the OS running yet?
How do you start a distributed (peer-to-peer) system where the clients depend on their currently known peers to find out about new peers in the system?

In that case, bootstrapping refers to a way of breaking the circular dependency, usually with the help of an external entity, e.g.

You can use another C compiler to compile (bootstrap) your own compiler, and then you can use it to recompile itself
You use a separate piece of code that sets up the initial process  without depending on any functions provided by the OS
You use a hard-coded list of initial peers or a hard-coded tracker URL that supplies the peer list

etc.
Comment: This really gets at the heart of the question. Where the other two answers, miss it completely.
Comment: I feel like this explanation was the most relevant to software development in general. Really brought the concept home for me
Comment: In my humble opinion, this is the wrong context.
Comment: Best answer for me, I was reading the design document of golang, and got confused with the term `bootstrapping` used there- in their case the question was how do we compile golang using a compiler written in golang. Well, this answers my question.
Comment: How do you compile X if you need X? just take a look at guix https://guix.gnu.org/en/blog/2023/the-full-source-bootstrap-building-from-source-all-the-way-down/
Comment: Very good and important answer. Worth mentioning that the term "bootstrap(ping)" is also used to describe the situation itself where something depends on itself; eg. in statistics and (conventional) machine learning, or even in reinforcement learning, etc.
Answer: See on the Wikipedia article on bootstrapping.
There is a section and links explaining what it means in Computing. It has four different uses in the field.
Here are some quotes, but for a more in depth explanation, and alternative meanings, consult the links above.

"...is a technique by which a simple computer program activates a more complicated system of programs."
"A different use of the term bootstrapping is to use a compiler to compile itself, by first writing a small part of a compiler of a new programming language in an existing language to compile more programs of the new compiler written in the new language."
Comment: Could you please quote or paraphrase so readers won't have to traverse multiple websites to get their answer?
Comment: "Software Industry, the: unique business of selling substandard goods legally, and charging for their upgrades."
Comment: I was looking for an answer **Bootstrapping in Compiler**. This was helpful.
Answer: In the context of application development, "bootstrapping" usually comes up when talking about modular and/or auto-updatable software.
Rather than the user downloading the entire app, including features he does not need, and re-downloading and manually updating it whenever there is an update, the user only downloads and starts a small "bootstrap" executable, which in turn downloads and installs those parts of the application that the user needs. Additionally, the bootstrap component is able to look for updates and install them each time it is started.
Comment: I never heard the term "bootstrapping" used in that particular context.
Comment: @AturSams composer installs dependencies but it does not bootstrap your php application.
Comment: Commonly used in regards to php applications (for instance using Composer to accomplish this)
Comment: @DanielW. Yup, the whole definition is more confusing than helpful.
Especially with a commonly used CSS framework named Bootstrap and an ML technique to reduce Decision Tree variance, Bootstrap Aggregation and some other definition in the context of BIOS bootloader. It is my opinion that this term should be avoided completely. :D
Answer: Alex, it's pretty much what your computer does when it boots up. ('Booting' a computer actually comes from the word bootstrapping)
Initially, the small program in your BIOS runs. That contains enough machine code to load and run a larger, more complex program.
That second program is probably something like NTLDR (in Windows) or LILO (in Linux), which then executes and is able to load, then run, the rest of the operating system.
Comment: Although I read all of the answers (which expanded on the term well and I voted some up), this simple "booting" a.k.a. "bootstrapping" comparison gave me the best motivation to read all the others to connect the dots. Srsly, it was like explaining a complex topic to a 5 year old and they get it. Thanks.
Answer: For completeness, it is also a rather important (and relatively new) method in statistics that uses resampling / simulation to infer population properties from a sample. It has its own lengthy Wikipedia article on bootstrapping (statistics).
Comment: Which is why I said 'relatively': Efron's initial articles are from the early 1980s as opposed to say the beginning of the robustness literature from the 1960s.
Comment: Relatively new? It was part of my statistics education at least 15 years ago.
Answer: Boot strapping the dictionary meaning is to start up with minimum resources.    In the Context of an OS the OS should be able to swiftly load once the Power On   Self Test (POST)  determines that its safe to wake up the CPU. The boot strap  code  will be run from the BIOS. BIOS is a small sized ROM. Generally it is a   jump instruction to the set of instructions  which will load the Operating   system to the RAM. The destination of the Jump is the Boot sector in the Hard Disk. Once the bios  program checks it is a valid Boot sector which contains  the starting address of the stored OS, ie whether it is a valid MBR  (Master Boot Record) or not. If its a valid MBR the OS will be copied to the   memory (RAM)from there on the OS takes care of Memory and Process management.
Answer: As the question is answered. For web develoment.
I came so far and found a good explanation about bootsrapping in Laravel doc. Here is the link

In general, we mean registering things, including registering service
container bindings, event listeners, middleware, and even routes.

hope it will help someone who learning web application development.
Answer: Bootstrapping has yet another meaning in the context of reinforcement learning that may be useful to know for developers, in addition to its use in software development (most answers here, e.g. by kdgregory) and its use in statistics as discussed by Dirk Eddelbuettel.
From Sutton and Barto:

Widrow, Gupta, and Maitra (1973) modified the Least-Mean-Square (LMS)
  algorithm of Widrow and Hoff (1960) to produce a reinforcement
  learning rule that could learn from success and failure signals
  instead of from training examples. They called this form of learning
  "selective bootstrap adaptation" and described it as "learning with a
  critic" instead of "learning with a teacher." They analyzed this rule
  and showed how it could learn to play blackjack. This was an isolated
  foray into reinforcement learning by Widrow, whose contributions to
  supervised learning were much more influential.

The book describes various reinforcement algorithms where the target value is based on a previous approximation as bootstrap methods:

Finally, we note
   one last special property of DP [Dynamic Programming] methods. All of them update estimates
  of the values of states based on estimates of the values of successor
  states. That is, they update estimates on the basis of other
  estimates. We call this general idea bootstrapping. Many reinforcement
  learning methods perform bootstrapping, even those that do not
  require, as DP requires, a complete and accurate model of the
  environment.

Note that this differs from bootstrap aggregating and intelligence explosion that is mentioned on the wikipedia page on bootstrapping.
Answer: I belong to the generation who flipped switches to enter a boot program. In the early 1980s, I worked on a microcomputer called Micro-78, developed by Electronics Corporation of India Ltd (ECIL). It was a sort of clone of Altair 8800. I distinctly remember what happens when a small boot program was entered using the toggle switches and executed by pressing a button. The program reads a second boot program contained in the 1st track of the floppy disk and overwrites it on itself in such a way that the second boot program starts executing to load a disk operating system. I think the term "bootstrap" refers to this process of the first boot program reading and overwriting the second boot program on itself, in a way "pulling itself up" with the additional functionality of the second boot program. That may be the origin of the original meaning of "the bootstrap program".
Answer: In terms of it in regards to using the popular Twitter Bootstrap I feel like this type of bootstrapping is the action of integrating a modular component into a Web application without the Web application having to even acknowledge the modular component exists until it needs it or references it.
The developer can seamlessly integrate a default copy of the CSS Twitter Bootstrap theme by simply loading (referencing) it into the Web application. Vuola! Then you may need to override some of these changes, but you can do so in such a way that the resource/component is untouched and completely reusable.
This same concept is how Web Devs implement jQuery APIs and so on, but it's not really expressed by Devs as bootstrapping per se. What it does is it improves flexibility and reusability while allowing the isolation of different components/resources of an app to reside freely either on the same server/s or possibly on a CDN.
NOTE: In computing bootstrapping deals with the MBR and in UNIX it requires a special bootloader or manager which is a small program in ROM that loads the OS into RAM. If you think about it the same concept takes places in the action of the bootstrap loader checking the MBR and loading the OS based on this table which occurs without the OS having any idea that this takes place.
Answer: IMHO there is not a better explanation than the fact about How was the first compiler written?
These days the Operating System loading is the most common process referred as Bootstrapping
Answer: Bootstrap file is responsible for loading contents of main file. It is a wrapper around main file. This way we can catch errors if loading of file was unsuccessful for some reason.
Answer: As a humble beginner in the world of programming, and flicking through all the answers here after seeing this word used a lot in apparently slightly different ways in different places, I found reading the Wikipedia page on Bootstrapping (duh! I didn't think of it either at first) is very informative to understand differences in use of this word. Could it be......on extremely rare occasions......Wikipedia might even have better explanations of certain terms than....(redacted)? Will they bring in rep points on Wikipedia though?
To me, it seems all the meanings something to do with: start with something as simple as possible Thing1, make something slightly more complex with that Thing2, and now you can use Thing2 to do some kind of tasks more efficiently and quickly than you could originally with Thing1. Then repeat from Thing2 to Thing 3 ad infinitum...
I see it as closely connected to both biological evolution and 'Layers of Abstraction' (newbies like me see, ahem, Wikipedia, cough) - the evolution from 1940's computers with switches, machine code, Assembly, C, Python, AIs you can give all kinds of complex instructions to like "make the %4^% dinner to my default &^$% requirements and clean the floor you %$£"@:~" in drunken slang English or Amazon tribal dialect without them 'raising an exception' (for newbies again...you guessed it) - missed out lot of links there due to simple ignorance.
Then in certain specific software meanings:
Meaning1: Thing1 is used to load latest version of Thing2 (because of course Thing2 will be bigger than Thing1, just as Thing3 will be be bigger than Thing2).
Meaning2: Thing1 is a lower level language (closer to 1001011100....011001 than print("Hello, ", user.name)) used to write a little bit of the higher language of Thing2, then this little bit of Thing2 is used to expand Thing2 itself from baby vocabulary level towards adult vocabulary level (Thing2 starts to be processed, or to use correct technical term 'compiled', by the baby version of itself (it's a clever baby!), whereas the baby version of Thing2 itself could of course only be compiled by Thing1, cause it can't exist before it exists, right duh!), then child version of Thing2 compiles Surly Teenager version of Thing2, at which point programming community decides whether Surly Teenager's 'issues' (software term and metaphor term!) are worth spending enough time resolving to be accepted long term, or to abandon them to (not sure where to take the analogy here).
If yes, then Thing2 has 'Bootstrapped' itself (possibly a few times) from babyhood to adulthood: "the child is the father of the man" (Wordsworth, suggest don't try looking up the quote or the author on Stack Overflow).

What is bootstrapping?


Weight painting doesn't work properly if bones are moved

Question: I am following the RPG graphics tutorial  to learn how to rig and animate a body(Although I am following on blender 2.8). Everything has been going fine up until the weight painting. Now, the weight painting works fine if I don't modify the pose in any way. But if I do pose the model and try to paint, blender acts as if I didn't modify the pose at all. I can have both arms up in the air, but I will have to paint as if the model is in the resting position. Does anyone know what can be causing this?
The tutorial
Blend File
Answer: The good news is your .blend file is fine. I had no trouble weight painting after changing the pose.
If, by any chance you didn't upload your latest version of your project, please make sure Pose Position is enabled, the Armature Modifier is turned on in the Modifier Tab and remove all keyframes or set keyframes for the current pose on the current frame.
I hope this was helpful to you.
On a side note: you should switch the Shading from Look Dev to Solid in Weight Paint Mode, otherwise the textures will make it harder to see the colors from your Weight Paint.
Comment: This is really strange because you are the second person to say it works fine. It is the latest version of my blend that I sent and for some reason it's just not working for me.


What is Concert Pitch

Question: Could someone provide a simple (for beginners) answer to the question, "What is concert pitch?" I understand that different brass and reed instruments play at different pitches and that a C played on one is not necessarily a C played on another. I further understand that it is obviously a pitch that a total orchestra can tune to. But what is the proper definition?
Comment: My take: Concert pitch can (1) refer to the transposition of the written notes of a "transposing instrument" in order for that instrument's sound to match that of a "non transposing instrument for any given note. (2) Refer to the establishment of a standard "tone" as the note that the entire ensemble tunes to; in some cases A= 440 htz, but that tone is not necessarily universal. So, the definition of "concert pitch" is nebulous, depending on who you are talking to.
Comment: This isn't a duplicate. The other question was about tuning a guitar to concert pitch, which is clearly only option 1. It does not address the confusion of describing two different terms in the same way.
Answer: Two Definitions
The problem you appear to be running into is that there are two different definitions for the term "concert pitch":

The pitch as described using a non-transposing instrument, such as a piano. Sometimes the word "pitch" is replaced with a specific note name to describe the exact note, e.g. Concert B♭.

The frequency and pitch name that a band or orchestra is tuned to. The most common example is A440, which means that a non-tranposing instrument will be tuned so that the pitch A above middle C is 440 Hz.

Transposing Instruments
While these are accurate definitions, a beginner would likely also want to know what a transposing instrument is.
Many instruments have multiple versions that play higher or lower pitches. To make it easier to switch between them, the sheet music for these instruments will often be transposed so that the same fingerings correspond to the same notes, no matter how high or low the instrument. Such instruments are called "transposing instruments."
Examples include the B♭ Trumpet and B♭ Clarinet, where their C sounds like a Concert B♭. They have have to play D to play a Concert C.
Comment: The problem with this definition of "concert pitch" as A=440 Hz is that musicians don't actually use the term to mean that.  I suspect that dictionary writers stumbled on it as a way of disambiguating their definitions of the real meaning of the term ("the pitch and that nontransposing instruments play") without realizing that some orchestras use an A that is other than 440 Hz, not realizing that they were thereby inventing a new sense for the phrase that nobody actually uses.
Comment: @phoog I had only heard of the first usage myself, but the second usage is attested as well. Furthermore, the two definitions don't overlap in any meaningful way, meaning it would be difficult to mistake one for the other. If someone mentions a frequency, they must be talking about definition 2. If they mention only a note name, then they must be using definition 1.
Answer: if you look at the saxophone family each instrument produces a different note when playing a C fingering.
Tenor saxes are B♭ instruments. So if you play a C fingering on a tenor you will hear concert pitch B♭.
Alto sax is an E♭ instrument. So if you play a C fingering on a alto you will hear an E♭ concert.
This is a problem if you say play a C and each instrument plays a C fingering producing different notes.
If you say please play C concert the tenor will play D and the alto will play A and they will both sound like C!!
You may be asking yourself, well why!? The reason is that you may play 4 different saxes and transposing in your head would be very difficult. Especially if you are switching instruments in the same concert or even the same song. But if you are reading and the composer transposed for you you can just play the fingering that is indicated and the note will sound correctly. Just make sure you are reading the correct score because now as you can see the alto score and tenor scores will be written differently even if they are playing the same pitches.
Answer: For transposing instruments (like much of the brass family and some of the wind family), the written note does not correspond to the sounded note.  Concert pitch is the sounded pitch.
For a B♭ trumpet, to play a concert pitch C5, it needs to play a written D5.  For a guitar, to play a concert pitch C5, it typically needs to play a written C6 (alternatively, be explicitly written with an octave transposing clef, a violin clef with an 8 underneath, a practice that is only slowly taking hold).  A soprano recorder has a concert pitch of C6 for a note written as C5.  Horns tend to be off by a fourth.
When coordinating with other musicians playing different instruments, the communication about pitches is usually done in concert pitch as a "common language".  The conductor usually talks in concert pitch as well.  There may be some exceptions, like octavating (contra) bass instruments: that they are sounding an octave lower than written tends to be an "implementation detail" of the bass group they are a part of.  But since it is rare to talk about octaves anyway, this rarely is an issue.
Comment: In modern usage, horns are off by a fifth, not a fourth.  In earlier times they were off by a variable amount that could be anywhere from not at all to a major ninth.
Answer: I'm mainly providing an answer to address some comments about Wikipedia not providing adequate sources and the idea that "concert pitch" is supposedly not used to refer to a pitch standard (but rather only in the transposing instrument sense).  There has also been speculation that dictionary writers just made the first meaning up.  Apologies to OP if this is not a "simple answer" for beginners, but as there seems to be some controversy in answers and comments, I thought it might be helpful to provide background.
The original meaning of "concert pitch" in English referenced emerging pitch standards in the 1700s.  Merriam-Webster notes this sense of an international pitch standard from ca. 1735 (though, admittedly, their definition of "international pitch" doesn't give the historical variance in that definition, which wasn't 440 Hz in the 1700s).
The Oxford English Dictionary gives an example of this internationalization from 1772:

Concert or Opera Pitch, for a Vocal Performance &c. from which all
  other notes may be proportioned.—The Lombardy, and Venice Pitch, is a
  Tone higher than ours, or theirs at Rome.

The development of the tuning fork in the early 1700s was instrumental in this concept, hence a dictionary from 1783 can claim that a "pitch fork" (i.e., tuning fork) can be

a device for tuning musical instruments to concert pitch

This meaning continued as the primary one in common use throughout the 1800s.  Usually ensembles tuned to a particular reference pitch.  From an 1848 dictionary:

Concert pitch, the pitch, or degree of acuteness or gravity [highness or lowness], generally adopted for one given note, and by
  which, consequently, every other note is governed.

When Alexander Ellis, perhaps the greatest English-language authority on pitch standards of his day, wrote his series of articles on The History of Musical Pitch (1880), he employed the term concert pitch in this manner.
As noted by other answers, in modern musical practice the term concert pitch is also used more generally to refer to the sounding pitch of a transposing instrument.  This meaning likely comes out of the German tradition that differentiated Kammerton ("chamber pitch," sometimes translated as concert pitch) and Chorton ("choir pitch," which was generally higher and corresponded to the pitch of the organ).  As organs lasted for centuries and were much more difficult (if not impossible) to move to another pitch standard, there needed to be a way to convert the pitches of the other instruments (which followed current standards) to the organ (which was unchanging in its pitch standard) to allow various instruments to play together.
The English term concert pitch gradually acquired a related sense to those German terms, perhaps because it was frequently used as a translation of Kammerton when discussing the tuning of old organs.  (Bruce Haynes, in A History of Performing Pitch: The Story of 'A' (2002) makes reference to the English phrase chamber pitch occurring perhaps as early as the 17th century as a translation of Kammerton, but he gives no references that early.)  The concert pitch was thus not only the standard tuning of instrumental ensembles (as Kammerton was in German-speaking lands), but also the way of navigating between instruments pitched at various levels, i.e., what we now think of as "transposing instruments."
Around the time of Ellis's aforementioned study, one begins to see more discussions of the term concert pitch used specifically in reference to other transposing instruments.  For example, from 1874:

A B flat cornet is one on which the "open" notes, though bearing the
  names C E G sound B flat D F; that is, a whole tone lower than they do
  on a C cornet; and it is called a B flat cornet to denote that it is a
  whole tone below concert pitch, and that consequently, to enable it to
  harmonize with any instrument that is at concert pitch, the music for
  it must be written a whole tone higher.

One also begins to see the emergence of the usage to refer to specific pitches as "concert X" when they are transposed to the standard pitch scale, as in the following excerpt from the same page:

I might put it on to the printer that I am made to ask, "If the B flat
  of the cornet is concert C," instead of "is the C of the cornet
  concert B flat;" [...]

I don't know how much earlier that last usage might go, but that was the first I was able to locate in a quick search on Google Books.
With the international pitch standard settled around A4 = 440 Hz in the 20th century, the term concert pitch sometimes just refers to that pitch standard today.  It is also still used frequently in the original sense as the pitch standard to which an ensemble (usually a large instrumental ensemble) tunes, whether A440 or something else.  But the specific meaning referencing the relationship of transposing instruments to their absolute pitches in the non-transposed scale has probably become the most common meaning among practicing musicians, unless they frequently play with ensembles the employ various differing pitch standards.
Answer: Concert pitch is a concept that is useful when dealing with transposing instruments.  It denotes the pitch system of non-transposing instruments, which you can think of as a common language.  This is in contrast to "written pitch," which is each instrument's own language, as it were.
If you are talking about a horn part, and you mention the pitch C♯, it's ambiguous: you might mean the written C♯ that is the same pitch as the trombone's F♯, or you might mean the written G♯ that is the same as the trombone's C♯.  To indicate that you're naming pitches as they are written in the part, you prefix the pitch names with the word "written," as in the previous sentence.  To indicate that you're naming pitches as they sound (that is, in the pitch system used by nontransposing instruments), you use "concert" instead.
Suppose an orchestra is playing an E-major chord.  You want to discuss the tuning of the root.  The clarinet part is written for clarinet in A and has a written G.  The tenor sax has a written F♯.  The alto sax has a written C♯.  The horn has a written B.  It's much easier just to say "everyone playing a concert E here, tune your octave with the tuba."  But if you're just speaking to one player, it's usually easier if you use the written pitches.
Before writing this answer, I found that many dictionaries claim that "concert pitch" means that A is 440 Hz, but I've never heard it actually used in that sense.  I think some dictionary writer was stuck trying to squeeze an explanation of transposing instruments into a definition of "concert pitch" and hit on the pitch standard as a way to define it without having to explain how transposing instruments work.  Being unaware that some orchestras use an A that is other than 440 Hz, they were also unaware that they were thereby inventing a new sense that nobody actually uses.
Comment: Sorry, but your "real meaning" is the late addition to the party. Your comments that are attacking many of the answers here are incorrect. The original meaning of "concert pitch" (dating to at least ca. 1735) is the pitch standard to which an orchestra tunes. The OED cites from 1772: "Concert or Opera Pitch, for a Vocal Performance &c. from which all other notes may be proportioned.—The Lombardy, and Venice Pitch, is a Tone higher than ours, or theirs at Rome." There are numerous such examples over the centuries. The modern transposing instrument sense developed out of that.
Comment: Just to be clear: I'm not saying at all the "concert pitch" = 440 Hz (though I've heard some people use the term that way).  The term "concert pitch" predates that pitch standard, but originally in English referred to the tuning standard (whatever frequency that might be) for an orchestra or other large ensemble.
Comment: @Athanasius "the pitch standard to which an orchestra tunes" is rather different from "A=440 Hz," and is logically equivalent to "the pitch system of nontransposing instruments."
Comment: Several of your comments on answers here seem to indicate that you are claiming that "concert pitch" is not used in the sense of a pitch *standard* (e.g., A=440Hz or A=415Hz or whatever).  For example, in another comment you said: "Nobody uses 'concert pitch' to distinguish A=440 Hz from A=442 Hz or any other frequency."  And "'Concert pitch' has everything to do with the concept mentioned in the last paragraph of this answer, and nothing to do with whether A is 440 Hz or 442 Hz or 415 Hz or 430 Hz." Are you claiming you didn't mean that?
Answer: There is no actual pitch that is concert pitch. That's why we refer to it as concert pitch. It's whatever pitch is decided that the whole orchestra - all musicians - will tune to in order to be 'in tune' with each other
Often it happens to be A=440Hz, but that's not actually what's known as 'concert pitch'. It may be so in some parts of the world, but it ain't necessarily so. Many years ago, it could be much lower. Many years before that, it was whatever everyone tuned to and it really didn't matter too much - as long as everyone actually tuned to the same thing!
There is a second definition, too. A lot of instruments are transposing instruments. That is, their music is written out in a key that is different from that of non-transposing instruments, i.e. piano. The problem here is that, say with a B♭ trumpet, its music is written out a tone above 'concert pitch'. When a trumpet player sees a C note on the music, the note blown comes out as a B♭. Here, the B♭ is called 'concert B♭', but when discussing the music - the dots, the note is referred to as a C.
Comment: Phantom dvers again! Come on, tell what you think is unpalatable, with reasons. I want to learn as well ! Don't be shy. If you're unsure of your reasons, maybe you should be unsure of dv-ing! Don't get me wrong, I can take them, but the futility of having them in ignorance doesn't help - me or anyone reading.
Answer: "Give me an A!"
But which A? Different violinists would provide different A, from instrument to instrument andfrom orchestra to orchestra, from land to land, from town to town, from time to time ... if not orchestras worldwide would have in unison defined a standard pitch.
And this is not so long ago. You can imagine what problems musicians would have in our time when they are jetting around the world if there wouldn't be this standard pitch (which is still differing today and not so stable  as and definitely fixed as it would be desirable.
Edit
I add this link first to make clear that there are international attempts to define c.p. = 440 Hz.
https://en.wikipedia.org/wiki/Concert_pitch
The other problem you are mentioning (not all instruments are tuned in C) is quite different but can be solved by fine tuning if they're constructed near orchestra pitch. They are transposing instruments and their voice part is adapted to their difference to the C instruments.
To come across the critic of phoog I'm posting these 2 quotes:
In 1939, an international conference[17] recommended that the A above middle C be tuned to 440 Hz, now known as concert pitch. As a technical standard this was taken up by the International Organization for Standardization in 1955 and reaffirmed by them in 1975 as ISO 16. The difference between this and the diapason normal is due to confusion over the temperature at which the French standard should be measured. The initial standard was A = About this sound439 Hz, but this was superseded by A = 440 Hz, possibly because 439 Hz was difficult to reproduce in a laboratory since 439 is a prime number.
Despite such confusion, A = 440 Hz is the only official standard and is widely used around the world. Many orchestras in the United Kingdom adhere to this standard as concert pitch.[18] In the United States some orchestras use A = 440 Hz, while others, such as the New York Philharmonic, use A = 442 Hz.[19] The latter is also often used as a tuning frequency in Europe,[3] especially in Denmark, France, Hungary, Italy, Norway and Switzerland.[18] Nearly all modern symphony orchestras in Germany and Austria and many in other countries in continental Europe (such as Russia, Sweden and Spain) tune to A = 443 Hz.[18]
In practice most orchestras tune to a note given out by the oboe, and most oboists use an electronic tuning device when playing the tuning note. Some orchestras tune using an electronic tone generator.[20] When playing with fixed-pitch instruments such as the piano, the orchestra will generally tune to them—a piano will normally have been tuned to the orchestra's normal pitch. Overall, it is thought that the general trend since the middle of the 20th century has been for standard pitch to rise, though it has been rising far more slowly than it has in the past. Some orchestras like the Berlin Philharmonic now use a slightly lower pitch (443 Hz) than their highest previous standard (445 Hz)
https://en.wikipedia.org/wiki/Concert_pitch
Comment: "Concert pitch" has everything to do with the concept mentioned in the last paragraph of this answer, and nothing to do with whether A is 440 Hz or 442 Hz or 415 Hz or 430 Hz.

What is Concert Pitch


On Linux, is there an rc.local equivalent for shutdown?

Question: I've got a few commands that I run in rc.local so they are run last in the startup sequence. I would like to know if there is a similar facility for undoing the results of those commands at shutdown, like an rc.shutdown. Ideally, it would be run before any of the other /etc/init.d scripts.
Comment: This is highly distribution-dependent. Please add information about your distribution.
Answer: Not really (at least, to my knowledge).
If you've got SystemV style init scripts, you could create something along the lines of /etc/rc6.K00scriptname and /etc/rc0.d/K00scriptname, which should get executed prior to any of the other scripts in there.
Answer: ArchLinux does have a /etc/rc.local.shutdown file for this. I'm not sure about other distros
Answer: It is generally possible, but depends on the init-scripts system you have. If your distribution used a recent version of OpenRC (as Gentoo does), you could put any scripts in /etc/local.d/, call them <something>.stop and they would be run at system shutdown. For older versions, you'd have to put your commands inside local_stop() function in /etc/conf.d/local.
The order depends on the rc-system settings, but typically the local scripts are the last to run at startup and first to run at shutdown.
Answer: If you have upstart, you can catch the shutdown event and run a script when it is caught.
Answer: In Gentoo the "local" script does exactly what you ask for: It runs certain user specified commands upon 'start' and another set of commands upon 'stop'.


Marketing Cloud Automation studio won't update data extension

Question: We are having trouble updating records in a data extension from an automation. It creates new records but it won't update. We have the salesforce custom object ID set up as the primary key and the subscriber key linked up in the extension. We then run a SQL activity in the automation studio which "Updates" the data extension, but it doesn't update existing record, it just adds any new ones.
Can anyone help please?
Many Thanks
**** Edit ****
So here is my data extension, the ID is set to the primary key. I can't use the subscriberKey because it is a one to many relationship so there would be multiple records with the same subscriberkey in this data extension

My SOQL that is used in the automation to populate the data extension.
Select id,
Buyer_Type__c as PlotID ,
Developments__c as DevelopmentID,
Region__c as RegionID,
Lead__c as SubscriberKey,
Customer_Email__c as EmailAddress,
Status__c as Status,
Record_Type_Name__c as RecordType
from Interest__c_Salesforce
where Status__c = 'Active'

Comment: That sounds like your primary keys aren't lining up.  Can you go into more detail about what the PKeys are that you are using in the DE and the Pkeys on your data source?
Answer: Check that your update type/data action is toUpdate and not Append:


-X to all armor per hit: Is this a global effect?

Question: If my pet has a collar with a "-X to all armor per hit" modifier and attacks an enemy, will I also see the benefit of that armor reduction during my attacks on the affected enemy or is this only for my pet?
For example, let's say an enemy has 50 armor.  My pet attacks and degrades the enemy armor by 10, taking its armor down to 40.  When I attack the same enemy without any modifiers, will its armor be 40 or 50 relative to my attacks?
This question also applies to online play.  If I degrade an enemy's armor with my attacks, will the other players also benefit from a lower enemy armor or am I the only one who benefits since I was the attacker?
Comment: I would imagine that an effect would only be global if it applies a status effect, otherwise it only applies for that particular attack.
Answer: As mentioned over here in this question, the <code>-X armor per hit</code> effect applies a stacking debuff to the target with a five second, refreshable duration.
Due to this, the value of your targets' armor is being decreased directly, rather than being decreased under specific conditions (like if you use spell X, for instance). This means that any attacks you make, your pet makes, and your party makes will benefit from the effect.


Using TDD when developing a database schema?

Question: I am fairly new to TDD and database development. If I wanted to use test driven development when I am trying to create a database schema how would I do that? What are the common tools and processes used in order to do so?
Answer: Despite the answer being accepted, I would disagree with the statement: "TDD is for testing application. DB schema is not an application and you cannot test it per se."
TDD is for all IT work. TDD and Unit Testing, in particular, are (or should be) very much a part of database construction.
We do database construction using TDD; a data warehouse in our case.
There are two main ways we apply to databases.
Firstly, this is particularly important since the OLTP system is controlled by another team; and it is changed sometimes without us being informed. We do have interface schemas with schema binding on to try and protect us, but things still happen.
So, we collect the INFORMATION_SCHEMA.COLUMNS information on each table of interest to us then write a hash across this information, which the checksum result is compared to a known checksum value.
If the checksum mismatches, then we know the schema has changed.
I would now go on to address the complication with schema checking, that in TDD, you should build the test first then you do the programming ...
We build a 'shell' hash test initially, knowing it will fail (since you can't know the hash value until you have the full table structure), then follow the process as you normally would with TDD, build, test, modify test if necessary, retest, modify the build, retest, etc ...
Secondly, we can build tests that will verify the logic applied to stored procedures, functions, triggers and calculated columns.
Comment: my answer talks around schema changes, but TDD can also test logic that applies to calculated columns, database triggers and stored procedure / function calculations. I'll amend my answer to include these.
Comment: That's not TDD as much as using TDD tools to warn you if an external party has intruded changes to your system unannounced, right?
Answer: TDD is for testing application. DB schema is not an application and you cannot test it per se. You can test application which uses that schema.
Tests will help you determine if your application is still working correctly after refactoring, which may include any changes in the schema (or any other changes).


Can reverse stock splits create fractional shares with infinitely repeating decimals?

Question: Suppose I own 1 share of company A. Company A then decides to undergo a 1 for 3 reverse stock split. After the reverse split, I will own 1/3 shares (i.e. 0.333333... shares). The number of shares I own will be a recurring decimal. How will this work for record-keeping purposes? Will the number of shares be rounded to some fixed number of decimal places (e.g. 0.33 shares), or do the regulatory authorities forbid reverse stock splits that create these sticky situations for lots of shareholders?
Comment: Relevant: [In a reverse split, what happens to odd lots?](https://money.stackexchange.com/q/52205)
Answer: No you won't have a repeating decimal number of shares in the company.
You will end-up with an exact integer number of shares. When the reverse split is done, all fractions are turned into cash.
There are two reasons to do a reverse split. The first is to get the share price over a hard limit that is set by the stock exchange. The other reason is to get rid of small investors.
If it is the second reason then anybody that only has a handful of shares will see their entire investment turned into cash. This reduction in the number of investors can reduce the amount of oversight the company has via organizations like the SEC as the company edges towards being a non-public company.
The other way fractional shares in company could happen is during a merger or split. In those cases again fractional shares in the new company are issued as cash.
Now inside a stock or bond fund there can be a fractional shares. But they don't have repeating decimals. They cut off the fraction after a few decimal points.
Here is how Vanguard handles it:

For example, say you purchased $ 3000 of the Vanguard 500 Index Fund
  at $ 107.65. When we received your $ 3000, we would divide that sum by
  the price per share to calculate the number of shares you received. In
  this particular case, the fund comes to 27.86809103576405.... shares.
  On our website and in your paper statements, we would then round this
  number of shares to three decimal places and state that you now owned
  27.868 shares.
When you downloaded your recent transactions to Quicken, the OFX file
  creation process brings your share balance out to a much higher level
  of precision so that your transaction balances match. For example, we
  would pass a share value of 27.86809 to Quicken, so that when Quicken
  calculated the total of the transaction, it would equal $ 3000.00.
Comment: @mhoran_psprep did that not cause anyone with 59,000 shares to drop to 30,000 shares (plus cash)? That's quite an impact.
Comment: correct me if i'm wrong, but wouldn't a split for the second reason require a ridiculous divisor? If we assume all small shareholders hold 100 or fewer shares that would require a 1 for 101 split.
Comment: in 2010 https://sgbonline.com/gander-mountain-takes-next-step-toward-going-private/ gander mountain did a 1-for-30000 reverse split followed by a 30000-for-1 forward split, to get rid of small investor. In brought the number of investors to less than 300. And then took the company private.


Does 20 XRP become unusable once deposited in a wallet?

Question: If I'm sending, say 50 XRP, first time to an exchange or wallet, will 20 XRP be locked forever and become unusable? Since 20 xrp are required to activate that account.
Answer: If it's a native wallet on the ledger, then 20 XRP will not be transferrable, though you can use it to pay transaction fees. Exchanges typically have you pay into their account, so there's no reserve that you need to pay. For reasons that nobody has ever figured out, Poloniex does make you pay the 20 XRP reserve.


Benchmark dataset for decision tree algorithm

Question: I'm implementing a decision tree algorithm, and I'd like to get a feel for how it performs relative to other implementations. Can anyone recommend popular datasets for training and testing decision tree algorithms? I've found some resources like this, but I'm not sure widely used it is.
Answer: I would recommend the UCI repository you're mentioning. It has been around for quite some time, contains many data sets and is frequently referenced in scientific publications.
Answer: You're on the right track with the UCI repository.  MLcomp is another great resource, and will automatically score your algorithm on multiple datasets.
Answer: You could try having a look at the datasets from Kaggle competitions at kaggle.com. Some require a fair degree of pre-processing, but there are some relatively 'clean' datasets there. You can see how your algorithm performs by submitting predictions to either current or past competitions and see how well it performs relatively to other participants.
Answer: Thought I should mention milksets, a Python wrapper around some UCI datasets. It appears to have 7 of the datasets, and produces them as a simple 2D Numpy array.


Religious Blessing at a Non-religious Wedding

Question: My daughter has decided to have a non-catholic/non-religious wedding.  There does not seem to be any possibility of changing her mind mostly due to her fiance.  Needless to say this has caused some "discomfort" within my family.  While I know that the wedding can not be blessed by the Catholic Church, is there any type of a Catholic blessing or prayer that I can give at the wedding or at the wedding reception?  I am at a loss as to what else I can do.
Comment: Which country is this? The UK, for example, forbids any religious words at civil ceremonies.
Comment: If your daughter and her fiance are happy for you to, I'm sure the Catholic Church would be fine with you praying. Prayer is always a good thing to do. Are you asking though whether there is a recommended set prayer you could pray?
Comment: They can seek a dispensation from their bishop to forgo the canonical form. Otherwise, they will be entering an invalid marriage.
Answer: Let the Lord help you say the loving words: use Scripture
1 Corinthians 13, RSV has only ever moved me -- when I wasn't a baptized Christian and now that I am.  I've been hearing this at weddings since I was about 10.  My younger brother, a non believer, finds these passages poignant and beautiful in tone and intention.  You can't lose.

If I speak in the tongues of men and of angels, but have not love, I am a noisy gong or a clanging cymbal.
  2 And if I have prophetic powers, and understand all mysteries and all knowledge, and if I have all faith, so as to remove mountains, but have not love, I am nothing.
  3 If I give away all I have, and if I deliver my body to be burned, but have not love, I gain nothing.
  4 Love is patient and kind; love is not jealous or boastful;
  5 it is not arrogant or rude. Love does not insist on its own way; it is not
  irritable or resentful;
  6 it does not rejoice at wrong, but rejoices in the right.
  7 Love bears all things, believes all things, hopes all things, endures all things.
  8 Love never ends; as for prophecies, they will pass away; as for tongues, they will cease; as for knowledge, it will pass away.
  9 For our knowledge is imperfect and our prophecy is imperfect;
  10 but when the perfect comes, the imperfect will pass away.
11 When I was a child, I spoke like a child, I thought like a child, I reasoned like a child; when I became a man, I gave up childish ways.
  12 For now we see in a mirror dimly, but then face to face. Now I know in part; then I shall understand fully, even as I have been fully understood.
  13 So faith, hope, love abide, these three; but the greatest of these is love.

I have found that if you omit 11 and 12, most people don't notice, since it wanders from the nuptial theme in a different spiritual direction.
Granted, if this is one of the readings at the wedding during the ceremony, then you've got to reach for another bit of inspiration.  I'd recommend looking through the Song of Songs for a passage that moves you.
(And it happened again; as I reviewed this before posting, my eyes got wet with the power of this scripture).


Do Slows (Items/Skills) stack?

Question: So if you have a frozen mallet and you attack someone (while you have red buff) or you use a slow like Nasus' wither, does it stack with the other slow?
Answer:
Slow stacking
Slowing effects follow particular rules when stacking:
If a champion is affected by multiple slows, the strongest one will be
  fully applied, while the others are applied sequentially with 65%
  reduced effectiveness down to 35% of its original strength.
Slow effects derived from items' passives do NOT stack, even when
  coming from different champions. Only the strongest item slow is
  applied at any moment. The exception to this is the active effect of
  Randuin's Omen,  Hextech Gunblade and  Bilgewater Cutlass, which
  stacks with other slowing items normally because they are considered
  champion abilities for slow stacking purposes.
Attacking a champion with the  Blessing of the Lizard Elder buff when
  the target is already affected by that slow will reapply the debuff,
  resetting its duration. It will NOT increase the slow amount. The same
  holds true for the  Exhaust summoner spell.

Source
Answer: Slow stacking in league of legends is rather complicated. But here goes:
Passive item slows (even if applied from different champions) do NOT stack.
Eg. Rylais does not stack with Frozen Mallet.
Also exhaust and red buff slow do NOT with themselves.
Eg. reapplying red buff won't snare for more than the first red buff slow. However, red buff does stack with, for example rylais scepter.
Active item slows and abilities DO stack. Active item slows are: bilgewater cutlass' active, hextech gunblade and randuin's omen.
Here the rule is: The strongest snare counts 100%. Then the second strongest snare applied counts to 65%, and so on until 35%.
So if you use exhaust (40% slow) on a target with 400 movespeed, and then apply nunu's level 1 ice blast (20% slow), the slow will be:
1 - (1 - 0.4) * (1 - 0.2 * 0.65) = 47.8%
400 * 0.522 = 208.8 movespeed
I hope that didn't raise any more questions than it answered :p I can't make it any simpler, that's just the way it is calculated in this game.

Do Slows (Items/Skills) stack?


Tutorials or Documentation on SPServices

Question: Anyone provide the links for the code snippets for jquery spservices .i can't found the examples on spservices.Am eager to learn the basics in spsservices.
Answer: Please check the documentation of the library. There are some great quick-start guide and examples there.
Since it is not good to have only a line of answer, then you could also check this link for more examples.
Answer: Complete documentation of the SPServices library can be found on official site
Also you can refer this external sites for small demos or example:
Read list or document library items using jQuery SPServices in SharePoint 2013
Retrieve List items from SharePoint 2013 based on ID column using CAML Query
SPServices Cascading Dropdowns


Root user is not able to access

Question: I had a ubuntu user which has root level privileges but I haven't created password for it, there are other user also on the machine but none of them have sudo permissions, unfortunately permissions on .ssh directory in the ubuntu home directory has been changed and now I cannot login using ubuntu user credentials and there is no user with sudo privileges, so what options I have left with to get myself connected from ubuntu user's credentials
Comment: Start in single user mode?
Comment: https://www.vlent.nl/weblog/2010/09/06/locked-myself-out-root-account-ec2-ubuntu-instance/
Comment: I am using Amazon EC2 instance.
Comment: http://aws.amazon.com/articles/5213606968661598
Answer: I recommend booting into command line mode.
Then you can boot as root and then you can reset your users's password using the passwd command.
You can pay a look at: http://ubuntuforums.org/showthread.php?t=1904347
Someone seems to have the same problem than you do.
Greetings
PS: It might also be a good idea to set a privileged user in your sudoer file.
PPS: Sorry I lack the very small line were Amazon EC2 was mentioned. :/
Comment: I don't think you can do this with EC2
Answer: After paying attention to Amazon EC2 conditions, I found that you can import/export your virtual images.
Please, pay a look at: http://aws.amazon.com/ec2/vm-import/
From that point, you should be able to start your image locally with a visualisation tool. There you can start the previous procedure I mention earlier.
Let us know how it work. ;)

Root user is not able to access


Counter kick defence

Question: As can be seen in the video, the girl used armbar for counter the kick defense. I would like to ask if there is a tutorial of how to do it? Are there any other ways to counter the leg catch defense?
Comment: See [How to counter a grab to a kicking leg?](https://martialarts.stackexchange.com/q/8239/5961).
Answer: The flying armbar to counter a single leg attack should not be expected to work outside of demonstration. Notice for example, how the receiver helpfully presents their arm to be locked while holding the leg up. If they don't, you need to find another option.
Comment: It's amazing, isn't it, how many things work in a cooperative environment. :)
Answer:
ask if there is a tutorial of how to do it

Not that I know of.

Are there any other ways to counter the leg catch defense?

I wouldn't even call the way in the video a valid way.  As mattm and JohnP say, that armbar is impractical without a cooperative partner in a scripted demonstration.  And not just in the "oh, it'd be so hard to pull off" - it's actually fundamentally flawed in a self defence sense, because the kicker makes themselves even more vulnerable than they need to be long before they can counter.  If you watch in slow motion - or pause at the right point - you'll see that when she kicks her upper body is quite upright but at least her head is outside the reach of his jab, but after her leg is caught she actually squares up and leans in towards him while grabbing his uniform with her right hand - that means she's going out of her way to get into his punching range, and her right arm's busy and unable to move to deflect any punch he might throw.  Her left arm's way out to her left for balance, and consequently useless for defending herself, and he's free to reach in and grab her shoulder, which means he could equally have punched her in the head / fight over.  Practising or planning moves that involve transitioning through such total vulnerability and hoping your attacker won't do the obvious thing is suicide in a real fight.  You may also observe that he's leaning his upper body forward as he attempts to throw her, rather than maintaining an upright balance and shoving her with his right arm - that's because he's anticipating and cooperating with the throw, and wants to roll safely into position for her.
So, "any other ways".  If we take a figurative step back, the first problem was that the leg got grabbed.  First, if you kick with proper technique and focus, they're more likely to be knocked sideways, injured, and without getting a useful hold on your leg.  But, if they've read your intentions perfectly and moved sideways at just the right time to catch your kicking leg as it loses focus, then yeah - you may need to defend.  Options include:

rotating your torso and hips further away from the grabber while dipping the kicking leg's knee towards the floor, while dragging the leg down and through the grabber's hold
leaning in as she does in the video, but with both arms up in front and protecting you from any punch or grab he might attempt, leaning your body weight over your trapped leg: that means his grabbing arm will be dragged downwards and his body trapped under your weight, flat-footed.  You can then throw hand/arm strikes to his head: in particular, a right-arm armbar / ridge-hand strike or hook punch to the left side of his head will be very hard for him to defend against while his left arm is busy lower down holding your leg

if you can anticipate the grab, you can be moving in ready to strike his head even as your half-hearted kick - your bait - is being caught

after your leg is trapped, bend it again and slide your kicking leg's knee across towards their back hip, leaning in with your shin across their waist: that's a standard distance-preserving position used in Thai Boxing that will stop the grabber getting close enough to pummel you; they won't have too many good options and you can pick your moment to shove them away and disengage

If you notice someone is looking to grab you but they haven't done it yet, you can:

throw in some feints such as seeming mid-section kicks that change last minute to attack the head or thigh instead, or
both Thai boxing and Kyokushin karate commonly feint a kick then throw a teep / front kick, or
there's the mawashi kubi geri (roundhouse neck kick, aka question-mark kick, Brazilian kick, ...), or
swing the knee across without extending the lower leg for them to grab, then throw some other kick (side kick, hooking kick with the heel, vertical/slapping kick "uchi mawashi geri"...) or hand technique, or
just kick really, really hard and be ready to focus the kick a bit to the side of where they are when you start the kick, so even if they slip a little sideways you'll hit full power.

Counter kick defence


OS X 10.9 Mavericks subtle two-finger scrolling changes (on touchpad)

Question: I am still unsure whether this is dependent on, or even related to, the "Responsive Scrolling" feature rolled out in Mavericks.
Responsive Scrolling is intended to provide smoothness of scroll by doing such things as pre-rendering the areas surrounding the scrollable buffer. This in theory promotes buttery smooth scroll animation. I am all for that and I think such an abstraction layer is essential to great user experience. In practice, however, reports of increased lag or sluggishness were common in the early days of 10.9.
However, this topic is not about that. For me, I have not seen issues of this sort, thankfully.
But what I have noticed (and which I am having trouble finding others who have noticed it) is an aggravating subtle change to the behavior of scroll. Before, in 10.8, the two finger scroll on the touchpad controlled the scrollable buffer in a one-to-one fashion. Now, for very low finger motion velocities, the scrolling motion is accelerated.
This means the page will scroll much faster (something like 5 to 20 pixels per second) even when I am barely moving my two fingers at all.
In addition to this, this acceleration appears to have a rubber-band effect, where for slightly faster finger velocities, it actually slows down the motion of the buffer. It's almost like Apple is imposing on me some sort of "optimal scroll rate" and correcting me even though I know damn well how fast I want to move through the page to match my skimming speed, thank you very much.
And then, there is a separate higher-velocity regime where if finger velocity exceeds some much higher threshold the rubber-band adjustment is taken away. This feels good and proper and the momentum scrolling works just great.
I have become a bit of a speed reader/skimmer over the years and my rate of about half a page a second is just at this threshold, between the top range of the aggravating rubber-band-slowing regime and the "free-spinning" proportional control regime.
So, basically... I don't like this. I want it to feel like my fingers are directly dragging the scrolling buffer. I don't want "help". The non-physical "help" breaks the proportional physics of control, and it basically feels like they took a perfectly tuned rolling tube that I was using to view my documents on and squirted a magic rubber banding lubricant that defies physics into the bearing.
Note: It's possible that I am experiencing some side effect due to not installing the new OS fresh and instead updating a rather heavily "broken in" 10.8 setup. I've got BetterTouchTool and other widgets of this sort that took the ride over that might possibly be interfering and generating this strange behavior.
So anyway. The actual question is.... try scrolling a page in Mavericks at this rate of speed. Maybe try to do a comparison with a Mac that's running 10.7 or 10.8. See if you can spot this difference. If not, please tell me I'm crazy and maybe that means I can get this changed back to the way it should be.
Answer: I arrived at this page because I also perceived a subtle change in the trackpad scrolling mechanics after upgrading to Mavericks.  It does indeed feel that medium-speed scrolling is slowed down a bit from before (10.7 in my case).  I don't have a machine running the older OS to test this on, though.
Anyway, I turned up the scrolling speed to max in System Preferences > Accessibility > Mouse & Trackpad and find the new mechanics tolerable on that setting.  This is maybe not the solution you are looking for but perhaps other readers will be content as I am with this fix.
Comment: Honestly I got used to it in the space of a day. The redeeming factor is that slow movement makes the distance more "efficient", and even though it "drags" on you at medium velocities, well I think I tend to just avoid those velocities. My opinion of it now is that it's a perfectly usable system, it's just that I'd prefer for there to be conditional behavior which forces it never to compute a reduction in velocity. But the original behavior (which as far as i can tell, at least on the first swipe) is more faithful to reality and therefore strictly better.