Which F1 season had the fewest number of wins by someone outside the top two drivers?

Question: In 2021, 18 of the 22 races were won by Lewis or Max, with the remaining 4 races won by other drivers. Was there a season where there were less than 4 races won by drivers outside the top two in the championship?. For instance, if a season had 17 races and two drivers won 8 times each, that's a total of 16 wins, and only 1 race would have been won by a driver outside the top two.
Answer: There have been 5 seasons in which two drivers won every race except one:

1950. There were 7 races, with Juan Manuel Fangio and Nino Farina winning 3 each; the remaining race was the Indy 500, won by Johnnie Parsons.
1952. There were 8 races, with Alberto Ascari winning 6; Piero Taruffi and Troy Ruttman won the other two.
1963. There were 10 races, with Jim Clark winning 7 and Graham Hill winning 2; the remaining race was won by John Surtees.
1988. There were 16 races, with Ayrton Senna winning 8 and Alain Prost winning 7; the remaining race was won by Gerhard Berger.
2023. There were 22 races, with Max Verstappen winning 19 and Sergio Peréz winning 2; the remaining race was won by Carlos Sainz Jr.

There have been plenty of other occasions in which drivers outside the top two have picked up three or fewer wins between them, but the above examples are the most notable.


What is a safe amount of characters in a passphrase?

Question: The coldcard and trezor both has support for a passphrase. What amount of characters in this passphrase that would be considered unbreakable with current technology and within some years of bruteforcing?
Answer: Depends. Best to use a passphrase pulled from wordlists, like EFF Diceware's or BIP39, so then six words.
But do not go over 49 characters.
You can get away with a string under 20 characters if the characters are truly random generated, upper/lower.
Using a password manager is a great way to go if you don't want to use physical dice or coins.
Whatever you do, do NOT create one from your own brain, easily crackable in a short time no matter what, must come from high entropy, randomly generated.
Answer: Dont use a password manager, they tend to get hacked and leak information.
Dont use a random generator, if you loose it, you will never be able to guess it.
Usually 20+ character is a good and safe lenght, add names or words you could remember, adding numbers or dates.
Having helped hundreds of people with lost passwords, my experience is if you use a too complicated password, your will have a hard time restoring it if you loose the note.
If the passphrase would be just the password to your wallet, then disregard above, but since its used with a 24 word seed then its just an additional layer that does need as much security as a normal password would.


What is the difference between "affect" and "influence"?

Question: For example, if I want to say "the performance of this bike could be affected/influenced by many things", is there a difference between these two words?
My gut feeling is that "affect" sounds better, but I cannot find evidence in dictionaries.
Answer: Influence has two main connotations that affect doesn't.  The first is that of relation to process rather than state, so that something might affect a rock but rarely would circumstances arise where we could speak of that rock being influenced.  The second, and weaker, connotation is of emotive response being involved; this is probably the connotation that makes it feel less appropriate to use in reference to a bike's performance.  (We do speak of mechanistic processes being influenced, though, especially complex ones.)
Answer: I feel like "affected" as a slightly negative connotation whereas "influence" can go either way.
In the following sentence (made up for the occasion) ...

"The hand of a magnet takes its
  position under the influence of the
  Earth magnetic field but it
  can also be affected by the presence
  a nearby metallic object."

... one can clearly see the difference.
You will find that affect has several other negative meanings:

"He seems to be very affected by his loss."
"He is affected by Alzheimer's Disease"

In the example above "influence" is neutral but it can actually go either way. It can be deemed counter productive or beneficial.  However only your own judgement will tell you; depending on the nature of the influence.

"He started smoking under the influence of the other members of the band".
"The Government agreed to more ambitious goals under the influence of its 'Green' Parliament minority".

In other words your opinion will not be influenced by the fact that "influence" is usually positive or usually negative ;-)
Arguably though, "influential" has a slightly positive orientation.

"Philosophers like Voltaire were influential in the Age of Enlightenment".
Answer: Influenced means "having the character, development, or behavior changed by something or somebody."
Affected means "influenced or touched by an external factor."
Affected doesn't seem to have a negative connotation (and in most the cases it is considered synonym of influenced), except in sentences like "the gesture appeared both affected and stagy." In such sentences, affected means "artificial, pretentious, and designed to impress."


What are good load testing tools for IIS 7 web applications?

Question: The title says it all.  I'm looking for a good set of tools that I can use to load test a web application on IIS 7 before deployment.
Answer: I believe Apache Bench is pretty widely used for this sort of thing and can be used without any problem against other webservers. It's command-line based, so it should be pretty easy to script into your test suite or pre-deployment scripts.
http://httpd.apache.org/docs/2.0/programs/ab.html
Comment: ab is a good indicator but not much more. For real load testing you can't beat the 'web avalanche' appliance - you can rent them.
Comment: AB was just what I needed, I was having SSL problems using WCAT, and couldn't get most other tools to work. Didn't care much about the load, just wanted it to generate a bunch of requests so I could test my server.
Answer: There are a couple of good tools available:
Not free, but excellent if you are doing this professionally is Visual Studio Team System Test Load Agent.  MSDN covers how to set it up and run it here: Controllers, Agents, and Rigs.  You can download a trial here:

Visual Studio Team System 2010 Test Load Agent Beta 1
Visual Studio Team System 2008 Test Load Agent (90-day Trial)

As far as free tools...
Web Capacity Analysis Tool (WCAT):
Overview: Web Capacity Analysis Tool (WCAT) is a lightweight HTTP load generation tool primarily designed to measure the performance of a web server within a controlled environment.  WCAT can simulate thousands of concurrent users making requests to a single web site or multiple web sites.  The WCAT engine uses a simple script to define the set of HTTP requests to be played back to the web server. Extensibility is provided through plug-in DLLs and a standard, simple API.
Features:

HTTP 1.0 and HTTP 1.1 capable
Supports IPv6 Multithreaded Support
Supports generating stress from multiple machines
Extensible through C plug-in
DLLs Supports Performance Counter integration
Measures throughput and response time
Supports SSL requests
NTLM Authentication request support
Easily supports testing thousand of concurrent users

Download the x86 version here, and the x64 version here.
Answer: I have used Web Application Stress Tool before.  I'm wondering if this is a pretty standard tool to use, and if there are better alternatives
(WAS) can be downloaded here
There's also a kb article on how to install and use the application here
and a blog on how to use it here


Does "within" have an antonym? If so, what?

Question: Does "within" have an antonym?
If there is an antonym, which one is it?
Comment: This question made me think of a [song](http://en.wikipedia.org/wiki/Within_You_Without_You)...
Answer: Mehper beats me to it with outside, so I'll just throw in a third alternative for the sake of completeness. Historically, without is an antonym of within, and Merriam-Webster still says that the first meaning of without is "outside" without further comment, but I don't actually see it being used that way these days. Wiktionary marks that usage as "archaic or literary".
Comment: I remember singing the hymn "There is a green hill far away without a city wall" as a child. I could never understand why a green hill would need a city wall.
Comment: I recall this usage (also serving as a double-entendre) from the Beatles song "Within You And Without You".
Comment: The *New Oxford American English* has it as "[archaic or poetic/literary] outside: *the barbarians without the gates*."
Comment: Also the NOAD reports the use of _within_ to mean _outside_ as archaic/literary.
Comment: About the only time I ever hear "without" is when it's used in conjunction with "within", like "Mr Jones is well-known both within and without his home state."
Comment: Take care in using outside as the opposite of the following context: "Even though women may have considerable influence within their families and in their neighborhoods,...". It would be better to use 'within' and the opposite context: "Even though women may have considerable influence within the workplace,..."
Answer: Outside is an antonym to within.
For example: Within or outside of an organization or institution.
Answer: Outwith means outside of something.
Comment: This is a regionalism from Scotland and Northern England. It's not widely used outside these regions.
Comment: The NOAD doesn't report the word _outwith_; I agree with FX_ that is a regionalism.
Comment: It is, however, a rather nice word.
Answer: In Scottish English the antonym is outwith. I think it nicely resolves the problems with using without or outside, which often don't accurately reflect the intended meaning.
There's a picture of it on Wikipedia being used on a sign:
Answer: I agree with "without." Reminds me of a Marx Brothers exchange:

"Without" is a broader term, covering
  both "lacking" and "the absence of,"
  and also means "outside."
(This double meaning led to the Marx
  Brothers routine: "There's a girl
  waiting without." "Without what?"
  "Without food or clothing." "Well,
  feed her and send her in.")

From On Language, by William Safire.
Answer: To me the antonym of 'within' is 'between' and here is why:
Previous answers proposed 'outside' as the/an antonym of 'within'. However an obvious antonym of 'outside' is 'inside' which is different from 'within'. To find the 'true' antonym of 'within' I tried to find in which context(s) the word is used.
After a moment of reflexion I recalled that 'within' has to do with group theory and analysis of variance. In group theory the properties of elements falling into groups are analysed. For example think of a class of students divided into two groups: males and females. Each student can provide his or her weight. It is then possible to calculate the variation of weight either:
1) WITHIN groups (e.g. within males and then separately within females) and
2) BETWEEN groups (e.g. between males and females).
To me the 'real' antonym of 'wihin' whould be thus 'between'. However there may be other contexts I have not thought of where this is not valid. Precising the context in which you want to use the word would be valuable next time.
Comment: This is spurious logic.  Within groups can easily be contrasted with without or outside groups.  Within the group of men you find x.  Outside of that group you find y (*.i.e.* women).  If you mean *between* to mean both males and females, then you are still including the group of males, and hence it NOT the opposite.  It's just a widening of the group to be more inclusive.
Answer: I don't think 'without' or 'outside' groups mean the same as 'between' groups (and similarly for 'inside' and 'within').
Let me try to explain my point by using these words in a context of comparison. Let's imagine once each student has given her or his weight the teacher ask the students the following questions:
1) What are the difference of weight BETWEEN male and female students?
2) What are the difference of weight WITHIN male students?
3) What are the difference of weight WITHIN female students?
First let's imagine how the students could have answered. For question 1 a possible basic answer would be to calculate the mean weight of male students (let's imagine it is 70 kg) and then the mean weigth of female students (let's imagine it is 60 kg). The obsious conclusion (however possibly statistically incorrect) would be that boys are heavier than girls by a difference of 10 kg. For question 2 a possible answer would be to calculate the difference between the heaviest boy and the lightest boy. For question 3 a similar answer could be given for girls.
We have just imagined an example of comparison where 'between' and 'within' have precise meanings which can be understood by answering math questions. Now if you do not see the difference with 'inside' and 'ouside' let's use these words in the previous questions:
1) What are the difference of weight OUTSIDE (or WITHOUT) male and female students?
2) What are the difference of weight INSIDE male students?
3) What are the difference of weight INSIDE female students?
First you could say that the use of 'inside' in place of 'within' is not that much of a shock in question 2 and 3. However a possible interpretation would be to search for weight differences inside the body of each student which does not make any sense.
Second please read question 1 out loud. To me it does not make any sense and it is the strongest evidence that 'outside' or 'without' cannot replace 'between'. And to me the same applies to 'inside' and 'within' even if it is less obvious.


Starting a list workflow with list permissions but without site permissions?

Question: I'm trying to start a list workflow from a user with edit permissions on the list itself, but no access to the site that contains the list. Is there a way to do this? Right now the workflow gets suspended with an access denied error, but if I grant the user access to the site the workflow works.
Answer: If its a Designer workflow, Write your workflow logic inside AppStep block. This will elevate the privilege and user will be able to run the workflow. Check below link on how to activate Appstep.
https://msdn.microsoft.com/en-us/library/office/jj822159.aspx


CSS Question for Add to Cart

Question: I am using the RWD template. Trying to figure out how to change the color for the add to cart WHEN YOU CLICK ON IT. I was able to find the standard color as well as the hover color, however there seem to be a color when you click on it and I cannot find the CSS to change the color.
Answer: skin/frontend/rwd/default/css/styles.css  line 943
.button:hover, .cart-table .product-cart-actions .button:hover, #co-shipping-method-form .buttons-set .button:hover, .footer .button:hover {
        background: none repeat scroll 0 0 #2e8ab8;
        cursor: pointer;
    }

CSS Question for Add to Cart


Why does steam condensing release energy?

Question: When steam changes to water the kinetic energy and temperature remain the same, however bonds are created between the molecules. Since bonds are being created, why is this not an endothermic process where energy is absorbed and turned into bond energy?
Comment: You have it backwards.  Hydrogen bonds (not covalent bonds) are broken endothermically upon vaporization and re-formed exothermically upon condensation.  Unlike ice, liquid water forms very unstable and transient molecular clusters.  In a hydrogen bond, the potential energy between a hydrogen and the oxygen of a different molecule is *negative*.
Comment: @Bert Barrois hydrogen bonds are not broken upon vaporization. The water molecules remain intact and simply move farther apart. There are no chemical changes, just physical changes.
Comment: @ Bob D -- A hydrogen bond is not a covalent bond.  It is a weak (3 to 6 kcal/mol) electrostatic attraction between H and O of two different molecules.
Answer: Bonds are not created when steam condenses. Water  molecules in the vapor phase are far apart from one another and come closer together during condensation. That lowers the potential energy of the water molecules.
Since the total internal energy of the water is the sum of its potential and kinetic energies, and the kinetic energy doesn't change (temperature being constant during a phase change) the overall internal energy decreases. The loss is heat transfer out of the steam.

Why does the molecules being closer together decrease the potential
  energy?

Consider first a phase change from liquid water to water vapor. There are intermolecular attraction forces between the molecules of water. It takes energy (in the form of heat) to pull them apart in order for a phase change to occur from liquid to steam. Separating them increases their potential energy. An analogy (not exact) is it takes energy (in the form of work) to separate an object from the surface of the earth which increases its gravitational potential energy.
Now consider a phase change from water vapor back to liquid water. The opposite of the above occurs. The molecules come closer together and the potential energy decreases. That requires the release of an equal amount of energy in the form of heat. The gravity analogy is an object loses potential energy (converts it to kinetic energy) as it falls back to (decreases its separation from) the earth.
Hope this  helps.
Comment: Why does the molecules being closer together decrease the potential energy?
Comment: See my answer to your follow up question in the revision to my answer. Hope it helps clarify things for you.
Answer: The process of bind two things together releases energy. You'd need to add energy to separate the bound items again.
Examples that might help:

The Moon is bound to the earth. It would take energy (lots of energy!) to lift it far away

An electron is bound electrically to a proton in a hydrogen atom.  You have to add the ionization energy to pull it away, and it liberated energy (a photon) when it was captured.

So the weak binding that holds the water molecules together as a liquid liberates energy. That's the latent heat.
It's a common misconception that chemical bonds "contain" (positive) energy. But think about what happens if you burn hydrogen and oxygen: you make water, which contains stronger bonds than the individual H and O molecules, and the net result is a liberation of heat: the molecules have less energy than they started with.
Comment: I understand up to the chemical bonds part, wouldn't the heating add energy to the system which as you say would create stronger bonds?
Comment: Why do you think heating makes stronger bonds?
Comment: The heating adds energy to the system, so in your example shouldn't the bonds holding the water together be weaker than before?
Comment: To get steam to condense to liquid, you _reduce_ the energy. Each bond is what it is, with a certain amount of negative energy (energy released). As condensation happens, that released energy become heat energy which you remove to cause more condensation.


Can a subscriber be a publisher at same time

Question: I want to setup a topology for replication.
The scenario is such that a subscriber is subscribed to transaction replication based publisher (distributor running on publisher).
I then want this subscriber to be a publisher to another subscriber. I want the distributor to be on publisher instance (push).
Can some body help me out?
Answer: Yes, you can achieve the goal and implement replication topology. What I understood from your requirements is depicted in the diagram.

To do this follow these steps:

Enable distribution on Server 1.
Create replication, add articles and choose server 1 as publisher and server 2 as subscriber.
Once articles are replicated, enable distribution on server 2.
Follow step 2 for servers 2 and 3.


How to ascertain that the Rayleigh-Ritz variational method gives the exact value of the ground state energy?

Question: So the Rayleigh-Ritz variational method can be used to calculate the ground state energy of a quantum system. If $\phi(x)$ is a suitable (square integrable) and normalised function of the coordinates of a system, then we can set $$E(\phi) = \langle\phi\rvert H\lvert\phi\rangle$$
We can obtain an upper bound on the ground state energy by minimising $E(\phi)$, the lower the value that we get, the better the approximation. Now my question, how can one know that this method, when possible, gives us the exact value of the energy if we do not know that value beforehand. Is there a way to check that we got an exact answer or just an approximation, without knowing the exact value beforehand?
Comment: The Euler-Lagrange equation of the functional $\langle\phi|H|\phi\rangle/|\langle\phi|\phi\rangle$ is the eigenvalue equation. (Think of the eigenvalue as a Lagrange multiplier enforcing $\langle\phi|\phi\rangle=1$.) Since minima are critical points, you find that the minimizer is an eigenfunction. Since you're taking the minimum, this is the ground state.
Comment: @RyanUnger but the Euler Lagrange equation requires that the function has continuous second derivatives... Then it would only work if the eigenfunctions are in $C^2$, so that would not work for a discontinuous $V(x)$
Comment: Sure, you need some kind of elliptic theory if you want the EL equation to make sense classically. If you want technical details (which belong on math SE, not physics SE), check out Section XIII.1 in Reed--Simon (vol 4).
Comment: @ryan 's answer Is correct provided $E$ is an eigenvalue. In general you should take the infimum. The latter exists as long as $H$ is bounded from below, which is generally assumed.
Answer: There is no way of knowing how good or bad is the approximate eigenvalue that comes out of the Rayleigh-Ritz method.  This is probably the biggest weakness of the method.  Nevertheless, one can make the following qualitative observations.
Even if the ansatz is bad, the energy can be quite good.  For instance, imagine a trial ground state of the form
\begin{align}
\vert \tilde 0\rangle = \vert 0\rangle + \alpha \vert 1\rangle,
\end{align}
i.e. an ansatz ground state  $\vert\tilde 0\rangle$ where the exact ground state $\vert 0\rangle$ is contaminated by some fraction $\alpha$ of the first excited state.  Then it follows immediately that
\begin{align}
E=\frac{\langle \tilde 0\vert H\vert\tilde 0\rangle}{\langle \tilde 0\vert\tilde 0\rangle}=
\frac{E_0+\vert\alpha\vert^2 E_1}{1+\vert\alpha\vert^2}
\approx E_0 \left(1+\vert\alpha\vert^2 \frac{(E_1 -E_0)}{E_0}\right)
\end{align}
so the error is "only" of a few percent if $\vert\alpha\vert\approx 1/10$ and $\frac{(E_1 -E_0)}{E_0}$ is not too large.
The more quantitative way of increasing confidence in $E$ is to increase the number of variational parameters.   Thus, as a first step in estimating the ground state energy of a harmonic oscillator, we might consider the trial state
\begin{align}
\psi_1(x;\alpha)=\left\{\begin{array}{cc}
(x-\alpha)^2(x+\alpha)^2&\hbox{if } \vert x\vert\le \alpha \\
0&\hbox{otherwise}\, ,
\end{array}\right.
\end{align}
with $\alpha$ a variational parameter.  Following minimization w/r to $\alpha$, the resulting energy is
$$
E=\frac{1}{2}\hbar\omega \sqrt{\frac{12}{11}}\approx 1.04 E_0
$$
and is quite close to the exact value $E_0$ (even if $\alpha=(33)^{1/4}\sqrt{\hbar/m\omega}$ is not very close to the turning points of the function, showing that the function extends significantly beyond the classical turning points.)
Now, introduce a second variational parameter $\beta$ with an "improved" guess
\begin{align}
\psi_2(x;\alpha,
\beta)=\left\{\begin{array}{cc}
(x-\alpha)^2(x+\alpha)^2(1+\beta x^2)&\hbox{if } \vert x\vert\le \alpha \\
0&\hbox{otherwise}\, .
\end{array}\right.
\end{align}
which is still an even function of $x$ with no nodes.  This improved guess leads to complicated simultaneous equations arising from
$$
\frac{\partial E(\alpha,\beta)}{\partial\beta}=0\, ,\qquad \frac{\partial E(\alpha,\beta)}{\partial\alpha}=0
$$
but the final resulting value of the energy is $E=\frac{1}{2}\hbar\omega \sqrt{\frac{26}{25}}\approx 1.02E_0$.
Likewise, using $(x^2-\alpha^2)^3$ produces very little change in energy from the calculation using $\psi_1(x;\alpha)$, suggesting the original ansatz of $\psi_1(x;\alpha)$ produced a value of energy reasonably close to the exact value.
Of course this is no guarantee of anything, and it might well be that the family of increasingly complicated tests functions that one uses to see some "convergence" of the estimated $E$ are inherently inferior to others. Laughlin won a Nobel Prize by producing for the fractional quantum Hall effect a better trial wave function than the competition.
Answer: I am not aware of any theorem that can tell you how close you are to the ground state energy. However,the energy fluctuations $  \Delta^2 E=\langle \psi| H^2 |\psi \rangle - \langle \psi| H |\psi \rangle^2 $ can be used as criteria, if the correct ground state is guessed then $\Delta^2 E=0$.
Comment: This holds for any eigenstate, not only for the ground state, and for those you can check by simply applying $H$ to $\left| \psi \right>$ and seeing whether the result is $E \left| \psi \right>$ for some real number $E$.
Comment: I agree that it works for all eigenstates, yet it gives an idea of how close you are to an eigenstate. I also thought about applying $H$ to $|\psi\rangle$, but when you do this unless you get the exact eigenstate the result is not $E|\psi\rangle$.


Is my timing belt looking bad?

Question:

I would like to know how is my timing belt looking? Does it appear that it is about time for a change? I do not see obvious signs of cracking but the upper side of the belt does look glossy though not the underside. I do notice the belt rides a bit to the edge instead of the centre of the pulley, is this a problem?
Comment: Welcome to Motor Vehicle Maintenance & Repair!
Comment: Remember that in a 4-stroke engine, the lower pulley is half the diameter, has half the number of teeth, and the belt does not wrap as far round the circumference. The usual mode of failure is the crankshaft pulley ripping off those few teeth, not the belt breaking. The belt that failed on me looked to have a lot less surface wear than yours. (I got lucky -- mine failed on starting and did zero damage.)
Answer: There is just about no way to know the viability of a timing belt by looking at it. Your belt could last another 100k miles or it might pop tomorrow. This is why it is important to follow the change intervals given by the manufacturer. Most require a change at 60k miles (100,000 km) while others stretch it out to 100k miles (160,000 km). The longer change interval is usually with belts which are made of Kevlar.
That said, if you do not know the mileage on your belt, change it. It is better to spend the money for a belt now versus paying for an engine later.
Answer: There is nothing to worry about on these pictures.
Sane timing belts look more or less like this - smooth rubber surface, no cracks, no loose fiber, no de-lamination, no extra wear of the teeth.
This particular one looks even rather new.

Is my timing belt looking bad?


How do I ask a question on Stack Exchange?

Question:
Comment: @Rubén Your first reply to me is hostile, doesn't address my (simple) question, and indicates that you're not here to serve the community but to serve your _own_ purposes. There are ___so many___ things wrong with this question, and your ___only___ justification for answering it, is that the subject is related to "something" discussed _elsewhere_. By closing this you're preventing the community from answering. Frankly, it baffles me that you don't understand why this question should just be deleted.
Comment: Then why answer this, @Rubén?
Comment: This is a low-effort question that deliberately circumvented the restrictions in the form, in order to post a question without body. That's not something that should be rewarded with a long answer. That's something you close and delete if the OP doesn't update it. Instead, you answer it, _then_ close it...
Comment: That doesn't matter. This question isn't even about WebApps. The question is off-topic, it deliberately broke validation, and the OP clearly isn't interested in fixing it.
Comment: @Rubén I'm just asking you why this was answered, and I'm explaining why this shouldn't have been, and why this should've been deleted. On SE Meta, on SO Meta and on _so many_ other sites, this would've been long gone already. But instead of just answering, you get argumentative and, frankly, hostile. _"Please excuse me that I don't give you and every SE denizen who occasionally comes to help us a complete overview"_ is not a tone becoming of a moderator.
Comment: Humour translates badly in written text, especially if your communication skills are indeed poor. I'd advice you to avoid making jokes like that, @Rubén...
Comment: You have only entered a question sentence on the post title and added some characters to make the Ask Question form publish the question. This might be allowed on other sites, but it's not here. Please [edit] the post to replace the question body content with something like the context that led you to make this post. You might explain why you do not find the guidance on the Ask Question form helpful or what has motivated you to post this question on Web Applications Stack Exchange.
Comment: @Cerbrus You, the Community, are impossible to please. No matter what I do you always complain :P
Comment: Putting jokes aside, this was answered because at the time this question was posted it coincided with something discussed about site moderation.
Comment: By the way, a few moments ago I made i posted in Meta SE [Could users still get "This question body does not meet our quality standards"?](https://meta.stackexchange.com/q/394346/289691)
Comment: @Cerbrus I'm sorry to sound hostile to you. My intention was not that but to answer your question. There is background that might explain that, but it's not your fault, and it's not an excuse, so I deleted my comment. Still, my fellow mods/cm could see it when they reviewed the flag queue and took the appropriate measures. Regarding being "argumentative", please elaborate on that. How could I say the same without sounding hostile?
Comment: @Cerbrus Thanks for your reply. I didn't think that you feel offended by that comment. I'm sorry. I will not comment on your conclusions about it. Regarding the second part, I'm sorry my reply didn't please you. There are details that I will not share. Please excuse my poor communication skills.
Answer: Stack Exchange is not a place to make posts to ask questions. There are more than 100 sites related to Stack Exchange where questions might be asked.
You can learn what Stack Exchange is at https://stackexchange.com/about.
You can find the complete list of sites where you can ask questions at https://stackexchange.com/sites.
If you need help finding a site to ask a question that you want to ask, you might ask for a site recommendation at https://meta.stackexchange.com.
All the sites listed in https://stackexchange.com/sites have the same Ask Question form, but new users might occasionally be routed to a different form. When using the standard Ask Question form, please follow the guidance provided. This should be done in most cases, but other sites might have different rules. Your mileage might vary.
Do not circumvent the feedback received on the Ask Question form by cheating. If the Ask Question form tells you that the question body should not be empty, do not repeat what you have done in this question. If you repeatedly try to cheat, you might get bet banned from posting new questions.
Please take the Ask Question form guidance seriously.
From the answer to What can I do when getting "This question body does not meet our quality standards"? (rev 15 )

Why am I getting this message?
All new questions are subjected to a "minimum quality" filter that checks for characteristics of extremely poor questions. Your question has been caught by the filter.
What can I do to get the system to accept my question?
First, make sure your question is on-topic on the site you're asking it. You can check the site's policy by going to the Help Center, and, under the header 'Asking', going to 'What topics can I ask about here?'.
Make sure your question has

a clear title
a reasonable explanation of what your question is, sharing your research on the matter
commentary on what you have tried to solve your problem
correct use of English and actual sentences
proper spelling, grammar, capitalization, and punctuation

If your question is so brief that it could be looked up in a dictionary or reference book/site trivially, it might not be a good fit on our network.
Can you be more specific?
Exact details about the algorithm are not being released by the team.

I am against being explicit here.... Our check takes into account tags, title and body. We are not going to give breakdown of what was wrong, that is spoon feeding. (source: waffles)
If we provide a "formula" then it's just another way for users to bypass the question quality filters. (source: Jeff)

What are good resources on how to ask high-quality questions?
Fortunately, there are lots! See:

The "How to Ask" page (the link is basically the same page on every site)

How to ask a smart question

faq How do I write a good title?

What's the best way to ask a question if English isn't your first language?

Jon Skeet's Writing the perfect question (will take a few minutes to read)

Eric Raymond's How To Ask Questions The Smart Way, (this gets cited a lot but it's fairly long)

ABOUT RESEARCH IN WEB APPLICATIONS
We discussed requiring research in Web Applications questions
Does Web Apps Stack Exchange Require Research?. The summary on the discussion was posted by the Community Manager conducting it.


Driver For Phase Multiplier Option in Graph Editor > Modifiers > Built in Function Generator > Sine Curve?

Question:
I am animating multiple objects with different sine waves, but all of them should have the same phase multiplier. I am trying to declare a "global variable" that all the different objects share. I can set the value there and that can be used by all my objects. Somebody told me to "add a driver", but right-clicking this field does not give me the option to add a driver. Any tips?
Answer: you can't animate or drive those modifiers... a workaround would be to use a script, if you have many objects it could help you test different setups, but not so much if you need to animate the value... there may be other ways, what do you want to achieve?
<code>value = 0.5

import bpy
sel = bpy.context.selected_objects
ani = [o for o in sel if o.animation_data]

for ob in ani:
    for cu in ob.animation_data.action.fcurves:
        for mod in cu.modifiers:
            try: mod.phase_multiplier = value
            except: pass
</code>
Comment: I think your script solution works fine for me. I don't want to animate it. I just wanted like a central place where I can edit the value and speed up or slow down the animation, instead of editing it six different times. I anyway did manage a better way to do all that with a lot of changes in my animation strategy.
Comment: ok, glad you solved it


golf mk1 1990 clutch problem

Question: I was driving my golf and the clutch pedal was creaking a bit but working ok, suddenly i pushed the pedal down it clicked and went to the floor i got recovered and the mechanic showed me the cable coming through the bulkhead splitting the metal around it. I repaired the metalwork but went to reatach the cable but the clutch cable doesnt pull enough to work and wants to pull the cable through the bulkhead again,any ideas why this would do that
Comment: Cables can fail through stretching or shrinking, and the failure can be rather sudden. Are you confident that the clutch cable length is what it should be?
Comment: Not sure it was working fine till it came through the bulkhead but it seems too short now
Comment: If that is the case then the cable has probably bunched up (I've seen this happen on window regulator cables a lot). The cable will need replacing
Comment: Ok i'll check the length , it is pulling and returning the arm on the casing but doesnt seem to pull long enough
Comment: @SteveMatthews knows his way around Mk1 Golfs. His answer will best reflect your situation
Answer: It's a common problem on the Mk1 that the clutch cable pulls through the bulkhead and the repair plate is usually all that is required, however you may find that this no longer gives you enough travel on the cable.
Undo the two interlocking nuts on the gearbox end of the cable and remove them completely.  Thread the table through the fork split in the release arm and reassemble tightening only until the cable is tight against the arm.
Try the clutch pedal and see where the bite point is.  You can adjust these two nuts to move the bite point around under your left foot.
If it seems that the cable is trying to split the bulkhead again, it may be that you've fitted an inferior quality strengthening plate.  The ones I've fitted have been the stick on types that attach over the original bulkhead metalwork.
Comment: I'd be surprised if chemical metal holds for more than a few weeks.  It may be that your repair has forced the sheath of the cable to sit more proud than it usually would this shortening the effective length of the cable.  If it were my Mk1, I'd spend a few quid on the correct panel. https://www.vwheritage.com/shop/171898152/bulkhead-repair-patch-for-clutch-cable-mk1-golf-jetta-sciro/
Comment: Ok i tried a different method of repair i reshaped the metal and used chemical metal both sides it fixed ok but the cable seems too short and getting the pedal back on leaves no pull on the cable
Comment: The repair seems ok i got it back to shape easily, could there be something wrong with the cable or clutch itself
Comment: It is very unlikely that there is an issue with the clutch itself.  The movement of the air is fairly small and limited by the bellhousing.  It could be that the cable has stretched of the end of the sheath has deformed but again this is unlikely with the behaviour you describe.

golf mk1 1990 clutch problem


Cross Object Field Update/Reference in Workflow Rule

Question: We have a unique scenario where guests can create/submit Applications. Someone on the backend creates a Token object that contains the link to the public portal that the guest uses to create/submit an Application, and emails said link to the guest. This token has an isActive flag so after a guest submits their application(s) we can set that isActive flag to false to essentially kill the link (if they try and access the link after isActive = false, they are routed to an error page).
Usually, internal users are associated with Applications they have created/submitted so its easy to keep track what Applications belong to which users, but since these are now guests there is no one-to-many relationship like we have with internal users.
Each Token object created has a unique name (Api name of "Name") that I have added as a field (Token Name) to the Applications object so now whenever a guest creates an application by using a link from a Token object, said Token object's name (ex. ATR - 8374) is added to the Application on insert. Basically creating a one-to-many relationship between a Token and the Application(s) it might have associated with it.
Since the guest may have more than one application to create/submit and the difficulty to update records as a guest user to begin with, I would like to use a workflow rule to handle the setting the IsActive flag on the Token object to false. Basically, the criteria is if all Applications with the same Token Name (ex. ATR - 8374) have a Status of 'Submitted' then look back up to the Token with the same Name (i.e. Token Name from Applications__c = Name from Token__c) and set the isActive flag on said Token object to false.
Is there a way in Workflow rules or maybe in another declarative approach in Salesforce to cross reference another object's fields? The main object in this workflow rule will be the Token object were we will be referencing the Name and isActive field, and we will be cross referencing the Status field and Token Name field from the Application object.
Answer: You can't do this with a Workflow Rule. You will need to build either a Flow or an Apex trigger in order to be able to

React to changes on the Application object.
Query for other Application objects with the same Token Name.
Verify their statuses.
Query for and update a related Token.
Comment: Thank you. I will try a flow first and turn to code as a last resort


Is it must to follow this Sunnah

Question: Prophet (PBUH) used to eat on ground by spreading a mat on the ground and I know this is a Sunnah. Is it obligatory to follow this Sunnah or is it Mustahab?
Jazakallah Khair
Comment: Sunnah by default is a recommendation (it is the best way) unless emphasized otherwise. It is however regarded as disrespectful or sinful to refute or reject something that is sunnah: to make clear what I mean to say if somebody told you that the prophet used to do such and such and it is sunnah and could provide a hadith you shouldn't reject it, just because it is sunnah, even if you don't feel like doing so if this was about something he liked to wear or eat as his habits are not a must for others.
Answer: It is highly mustahab as the Prophet SAW was an example for us, and we should try to follow his example. His habits are part of the Sunnah, and it is highly recommended but not obligatory that we follow them.

Is it must to follow this Sunnah


Apple Itms-services:// Problems in ASP.NET

Question: I have a problem. In my asp.net application I store the *.plist and *.ipa files in a sql database.
Over a webcontroll I access them (http://domain/asppage/dist/filecontroller.aspx?plistId=2).
So on computer it works perfect.
If I try to download over iPad it doesn't work, also if I add the "itms-services://?action=download-manifest&url=" thing.
But I can download over ipad if I directly point an uploaded *.plist file.
So isn't it possible to download a database stored plist file over the link itms-services://?action=download-manifest&url=http://foo/dist/FileController.aspx?plistName=Approvaltest" from the iPad?
Comment: it's solved, watch below
Answer: I solved my problem.
If you want to use parameters in your link together with itms-services, please encode your chars. So for the "?" (questionmark) use %3F and for the "=" (equal) use %3D.


'Invalid or corrupt kernel image' error while booting from USB stick

Question: I got the Ubuntu 11.10 32-bit edition and i used Unetbootin to write the ISO to a usb stick.After that i tried to boot from the stick,having changed the BIOS boot settings,and when the first interface shows up with the choices of istallation,whatever choice i select i got the message"invalid or corrupt kernel image".I use a netbook with windows 7 on it.I tried different usb sticks but same again.I also tried Universal USB installer instead of Unetbootin but same again.Any idea of what happens?I am using ASUS 1000H.The USB doesn't work in one more PC i tried to,but i also tried a second USB to both of the two computers and same again. I downloaded the ISO image once again and follow the same procedure but same again
Comment: It's possible that the image you are using is corrupt.  You may try downloading the image again to see if that helps.
Comment: What netbook are you using? Do the same USB pens work in another PC?
Answer: You can verify downloaded Ubuntu images using md5sum. Here's a simple example to get the hash for a DVD image:
$ md5sum edubuntu-11.10-dvd-amd64.iso
f323d7e7b9686eb9c5babd94961e5df1 edubuntu-11.10-dvd-amd64.iso

Now you can compare that against the Ubuntu Hashes page. In this case they match up meaning what I downloaded matches the original copy (with 99.99something percent accuracy).
If you downloaded an ISO not on that list you can usually still find a hash but it depends on the ISO's source. If you grabbed it from the daily page, there is a MD5SUMS file in there but it obviously changes every day.
If you can't verify the image, download it again and check it right away. It might be worth using the Bittorrent download options as that has built-in checking.
The following doesn't apply to you (you've already swapped out USB sticks, strongly suggesting it's an image issue), but it might help people in the future.
If your image verifies correctly but still doesn't work, just try copying it to the USB stick again. In some cases you might find you have a stick that just refuses to work (I've had a couple of old, cheap disks not boot Ubuntu. I later found out that they were just shredding any data going in and out of them so chucked them. In other words: you might want to try another stick.
Comment: It probably isn't an image problem, as this error appears to many users. Even for the ones using Bittorrent to download the image, which already has its own verification built in. I think it is a problem of Unetbootin or the like, which are not yet upgraded by the author to support the newest Ubuntu release. My solution works (selecting manually).
Comment: I have not had good luck creating bootable USBs with unetbootin. I've switched to dd and all is good.
Answer: For me with Ubuntu 13.04 the solution was:

When the boot prompt appears with the countdown going from 10 to 0 I had to select manually »Try Ubuntu« or »Install Ubuntu« and it worked.
But if I waited the 10 seconds the automatic choice called »Default« was selected and then the error appeared. So: Don't wait for the countdown, make a selection.

I created the USB stick with Unetbootin.
Answer: I've had the same error previously, I solved it by formatting my USB to Fat16 format and then using the Universal Windows Installer. Give it a try.
Comment: Did not work for me with Unetbootin and Ubuntu 13.04 AMD64.
Answer: I had the exact same issue with Ubuntu 12.04 LTS and solved it by downloading the image from another mirror. Apparently I was downloading a corrupted file.
Answer: Please try and recreate another bootable USB installer - see official article about installing ubuntu from USB as a guide.  Lastly make sure you are using a larger capacity memory stick for the bootable disk - I would recommend anything from 4GB upwards just to be sure. Good luck


Annatto Oil Substitute

Question: We have a recipe that calls for us to make annatto (achiote) oil and fry some chilli peppers in it.  We are unable to find annatto seeds.  Is there a good substitute?
Answer: can you even find the whole annatto seed? that's what makes the oil that color. i don't think it really imparts a much of a flavor. a thread at chowhound.com suggests maybe using turmeric instead to color the oil -- i can see a bit of a resemblance.
Comment: "Can you even find...": I assume by "you" you mean "one", since the OP already said he can't find it. There wouldn't be so many recipes for annatto oil online if you couldn't buy it. I've seen it in some more specialty stores, though to be fair I'm originally from Texas. And it does have some flavor, though it's mainly used for the color.

Annatto Oil Substitute


Mailchimp Subscription in Wordpress Contact Form 7

Question: I have a Wordpress page using Contact Form 7. Is there a plugin I could install that would let me subscribe emails entered into this form to my Mailchimp List without changing the design of the form? Or could I add some code in the  inside functions.php, maybe to call the API? The form is at the bottom right of this page:
https://soulconnectcoaching.com/
Answer: While you can always try and custom code the functionality which is what I'd recommend if you enjoy coding. But if you want just the solution then you can use the CF7 MailChimp Extension which, I am sure, will exceed your expectation and the integration is just perfect.


What does a the prefix "a-" mean in "a-changing"

Question: For example in The Times They are a-Changin' (Bob Dylan).
I suppose it's old language. Where does this prefix come from and what does it mean?
Comment: See [this](http://english.stackexchange.com/questions/4604/the-times-they-are-a-changin)
Answer: It is a very old use, no longer used in Standard English (whatever that is), but still to be found in many dialects.
The a- is originally a worn-down form of the preposition on. In OE a standard way of expressing a state was as a preposition phrase with on—on slæpe, for instance, "on sleep" = "in a state of sleep". We have quite a few common adjectives and adverbs beginning with a- which are derived from this construction: ablaze, afloat, afoot, ago, akin, alike, alive, aside. (Note that the adjectives are almost never used attributively, before the noun, but only in predicates: this is because they arose not as adjectives but as preposition phrases.)
The English progressive construction, which "recategorizes" an event as a state, arose from the same construction: it was originally on + the gerund of the verb, in ModE The times are on changing, "The times are in a state of changing*. Over time the OE participle and gerund collapsed into a single form, and on was apocopated to a; and eventually the sense of this construction being prepositional disappeared and the a was dropped, yielding the ModE progressive. But it lingers in remote dialects like the English of the Appalachians, and it's useful for songwriters like Dylan who seek an archaic, 'folksy' tone.
Incidentally, many linguists now believe that the progressive construction was borrowed by the Englisc from the Brythonic tongues they encountered. Modern Welsh still constructs the progressive with BE + the preposition yn + the infinitive of the verb.
Comment: One should mention that German still has this older progressive  form:  Ich bin am Arbeiten  -I am on/at working/in the act of working. And this form is very common and wide-spread.  Because of this parallel I would not search the origin in Welsh.
Comment: @rogermue I am not knowledgeable about older German, but I believe that this *rheinische Verlaufsform* is a relatively recent development, not present in Proto-West-Germanic.
Comment: @rogermue It must be acknowledged, however, that in English, too, this progressive construction doesn't show up until pretty late, which weakens the case for Celtic borrowing.
Comment: @SoneyB  The form Ich bin am/beim Arbeiten/Werkeln is known and used in the whole of Germany; even in Switzerland and Dutch this form is used. Along the Rhein this form is extremely frequent and they have their own special variant and spelling. Unfortunatelly I don't know how old this form is. Wikipedia calls it am-progressive.
Comment: Does it really weaken the Celtic Hypothesis? It shows up *everywhere* suddenly after the English blackout (the Norman/Angevin period when we have very little documentary evidence of English at all), and written English was suspiciously stable for a long time before the Conquest (as written languages tend to be). I think it strengthens the case, myself.
Comment: I agree that it means "The times are in the process of changing, even right now." What's really interesting to me (and I'd never been a-thinking about this before) is how this construct can even be used when talking about the future, as in: "I'm going a-fishing." I suppose that's like saying, "I'm going to be a-fishing very soon, because I'm a-leaving right now."
Comment: @StanRogers The problem is that it doesn't show up in the early texts, before the Alfredian standardization--which is the time when Englisc and Cymry would have been in closest contact.
Comment: To me, that feels more like a "they're ruining our language" situation. Without the equivalent of graffiti, it's hard to know what was actually going on at "street level". Writing was scripture when it involved rocks, metal and expensive animal skins. I think the Celtic Hypothesis, particularly as it applies to do-support and the mania for the progressive, is probably the only reasonable answer, but unless and until we can get a time machine up and running...


No Catalyst Control Center

Question: I have installed the AMD driver in 12.04 using the Additional Drivers function. It works fine, fglrxinfo returns correct information, but it seems that there is no Catalyst Control Center, I tried installing fglrx-amdcccle, but still it does not appear when I search installed programs.
Answer: Just run amdcccle from terminal, you can also make a shortcut, to run as root use sudo amdcccle.
Answer: $ sudo apt-get install -y fglrx-updates

$ gksu amdcccle

This line will open the AMD Catalyst as Administrator (you will be prompted for superuser password to use it (your root password)
Answer: Are you using the Unity panel or the default Gnome?
Install Gnome Shell and then do a search for "AMD".
If this still dosen't work, try installign it from Synaptic Package Manager.
Comment: I'm using XFCE actually, I can run the file manually, but not from terminal or otherwise, only if I navigate to that folder.

No Catalyst Control Center


Interrupt handling with fpga in VHDL

Question: I am writing interputs for a fpga and dsp need to interact with a dual port memory shared dpram control in vhdl.
I have External IOs coming from the SPI bus on oneside to the fpag to be communicated with dsp and on the otherhand have a camera to the to the dsp.
So my intrups are like Havinf a FIFO being reset after everytime a FSM reads and writes the interrpts with dsp.
Now my problem is

I want to enable some particular interupts at a time and disable the others.
When make a masking with logical XOR function the other interupts coming from UART goes for a timeout.
When this is done the camera gets the signal but cant be controlled.

I use the following algorithm to deal with all asynchron inputs:

In event2reg_array_proc: save all inputs to parallel buffers "fifo_data_input_array", each input(flag) should be put into separate buffer.
In reg_array2fifo_proc2: read each buffer serially and save them in a fifo "fifo320x32".
In main FSM read the output from fifo and do the suitable processing, each cycle read out only one value, it should be one flag.

If you get some flags which remains in register even after processing, the reason can be:

In event2reg_array_proc: and reg_array2fifo_proc2:, if one flag (in buffer) has been written in the fifo, it should be cleared from the buffer. I use the "fifo_cnt" to control this. You can use simulation to check.
Line Camera sends the FRAME_VALID signal as same as the LINE_VALID signal, so you can get a lot of CAM2DSP_FRAME_SYNC_FLAG with Line Camera.

So can any one suggest any algorithm to enable particular interupts while the the camera is still communicating with DSP.
Answer: Your question is not clearly worded enough to enable a proper answer.
But one point is clear : XOR is not a good choice for an interrupt mask!
Either AND or OR would be a better choice depending on the logic of the interrupt handler.

Interrupt handling with fpga in VHDL


Keep away from your phone or keep away your phone?

Question: I'm trying to transmit this message, but I'm not sure what is the correct way to do so. In short words I'm trying to give an order.
Comment: It would help if you would explain what you are trying to say.  Do you mean "Stay far away from your phone" or "Make sure that your phone stays put away"?
Answer: Keep (or stay) away from your phone would be the proper way to order someone. Both sentences have an implied you in front of them. You keep away from your phone and You keep away your phone. But in the second sentence you are implying that the person should keep their phone away, rather than saying they should keep away from their phone. Usually you aren't ordering someone to keep their phone away from them, but rather are ordering them to keep away from their phone.
Comment: But _keep away your phone_ would be very odd wording even in that case: _keep your phone away_ would be **much** more natural.
Comment: I agree. I hardly ever hear anyway phrase it the other way.
Comment: Perhaps ordering is better than commanding? Anyway, I agree with the idea.
Comment: I agree. I replaced command with order.
Answer: "Keep away from your phone" is grammatical, but not very natural. A better way to say this would be "Stay away from your phone" -- meaning "keep a large physical distance between you and your phone". This is a strange thing to ask someone to do, though (unless you think the phone will explode).
"Keep away your phone" is not grammatical. To keep something away means that it is trying to approach you but you prevent it from approaching you. "Making loud noises will keep bears away." "An apple a day keeps the doctor away." But a phone is not alive or animate, so it cannot try to approach you.
To convey the meaning you want, I would say "Keep your phones put away". This means "it is OK to have your phone near you, but it must stay in your pocket or handbag or desk". (I suppose you could say "keep your phone away", but it is less natural.) You could also say "Keep off your phones". This would suggest that it might be OK to take your phone out, but you should not actually use it.
Comment: I think it's six of one, half a dozen of the other. Keep away from those cookies,  young man. Stay away from those cookies, young man. Same thing.


Recursive Backtracking to Display a List of Words

Question: I'm working on an Anagram Finder program. One of the methods I'm writing introduces the concept of recursive backtracking which I'm completely new to. I'm hoping to get some suggestions of how this works/how to make it work.
I'm trying to implement recursive backtracking in order to display a list of words from a dictionary text file to form anagrams for an input phrase. Here's what I have so far:
<code>public void printAnagrams(String phrase, int max, List<List<String>> anagrams) {
    if (anagrams == null) {
        throw new IllegalArgumentException();
    } else if (max != 0) {
        System.out.println("...");
    } else
        System.out.println("...");
    for (List<String> element : anagrams)
        System.out.println(anagrams);
}// End of printAnagram method
</code>
If max > 0, only combination of max words or less are displayed.
Since the program is pretty long, the background info is listed in the links below.
AnagramFinder class: raw code
Client class:  raw code
This is the expected results:
File name? dict2.txt
Phrase to Scramble? off course
All words found in "off course":
[core, course, cs, cure, for, force, forces, four, of, off, offer, offers, or, our, ours, re, score, so, source, suffer, sure, us, use, user]
Max words to include (Enter for no max)? 3
[core, off, us]
[core, us, off]
[course, off]
[cure, off, so]
[cure, so, off]
[force, of, us]
[force, us, of]
[of, force, us]
[of, us, force]
[off, core, us]
[off, course]
[off, cure, so]
[off, so, cure]
[off, source]
[off, us, core]
[so, cure, off]
[so, off, cure]
[source, off]
[us, core, off]
[us, force, of]
[us, of, force]
[us, off, core]
Answer: Try to use a linkedlist instead of list> it's better  and easier to understand


If I am going to dabble in the world of music, what aspect should I train more to build a solid base, and thus obtain better results(?)

Question: Good morning, I think I summarized it pretty well in the question, however, I mean exactly that "push" that a beginner must have, something that avoids excessive stumbles in their learning, of course I know perfectly well that everything is worked and results are obtained with effort and determination and that there will always be bad days, but I think it would be great to have this information in question, different opinions, nourish more and better my knowledge in this wonderful world. Thank you very much in advance.
Comment: What would you classify as a "solid base" - work ethic, talent, or both? Stronger willpower can improve work ethic, for example, and a better knowledge of music theory can build talent, so to speak.
Comment: I've submitted an edit of your question which I hope will be approved, but it would be good to have some more details about what types of musical situations you envision to play in? Do you want to be all round good? Playing blues, rock, classical...? Playing solo, groups or both?
Answer: Keep a practice book.  In it goes:

A log of your practice sessions, with what you practiced, where you think you did well, and where you need more work.  Example: "20 minutes of major scales, by 4ths, at 120 BPM.  Needs more work at this speed before going faster.
Notes about where you left off in an instructional book: "Up to page 22 of the intro book.  Working on the exercise at the top of the page.  Need to ask the teacher about the 4th measure."
Notes on things you want to refer back to, such as chord diagrams, progressions, etc.
Lists of tunes you've heard that you want to learn.
If you are taking lessons, then notes from those lessons.  What did your teacher show you, what are you supposed to be practicing?
Anything else you don't want to forget.

Practice time is probably our most valuable commodity when learning music, so using it more effectively is a big deal.  A practice book can make practice much more effective.


Use only one Coupon Code among a set

Question: Magento 1.9
We want to Create a group of different coupon codes , and there is chance that multiple coupon code can be received by single customer. Here system must restrict to use only one coupon code in that group. If customer uses coupon from another group then it can allow. Is there any possible way to achieve this?
Answer: Magento's out-of-the box Shopping cart price rule can do this. Under the Rule Information tab, use the field Uses per customer. Here you can set the limit to 1.

Note that this limit is applicable only for logged in users.

You can enter the group of Coupon codes in the same rule itself. For this purpose, under Rule Information tab, set Coupon to Specific Coupon and a new field will be introduced just below, called Coupon Code. In this field you can enter Coupon codes yourself or you can ask the system to generate the coupon codes for you by ticking the checkbox Use Auto Generation.

Use only one Coupon Code among a set


iOS Sync Device Name

Question: I have set up Google sync on my all my devices as I use the iOS Chrome app. When using the Chrome app I click on 'other devices' and my iMac device name shows up as iMac-2. I was wondering if it's possible to somehow rename/change my iMac device name. I've tried unlinking my iMac and linking it back up again but nothing has worked so far. I know it's only a small issue but it's bugging me.
Answer: The other devices list on Chrome uses the name of the Mac given to it, or the DCHP if that fails. To change the name of the Mac, go to System Preferences → Sharing and enter your desired name in the box at the top. You may need to log out and back in for Chrome on OS X to update the name.

iOS Sync Device Name


Does scanning a Flash NAND SSD for bad sectors help?

Question: If I have corrupt files and want to detect whether the Flash NAND SSD is the issue or whether the installation is just corrupt, would scanning for bad sectors help, or is this just useful on regular hard disk drives?
Comment: Before you do *anything* else, make sure you back up important data.  That being said, I *think* SSD will detect/reallocate bad sectors so is basically a non issue compared to bad sectors in spindle based drives.
Comment: What led you to believe that the installation was corrupt? And what program specifically is corrupt?
Answer: Generally speaking, SSD's firmware should  be taking care of re-locating your data if the current location is about to go bad. However. Nothing is 100% reliable, including flash firmware re-allocation algorithms. I'd say the chance of real bad sector (e.g. you write data, but cannot read it back, or read back not what you've written) on SSD is pretty low, but it won't hurt to scan for bad sectors either.
If some non-trivial amount of bad sectors do turn up on SSD I wouldn't use that SSD at all though, it means something is seriously wrong with either its firmware or the flash NAND itself.
Answer: I would first suggest querying the drive's SMART parameters.  For example, the drive might have exhausted its supply of spare memory blocks.  You'll want to use the most recent version of smartmontools you can easily get your hands on (one easy/free source: an Ubuntu LiveCD.)
Smartmontools can also activate a drive self-test and show you the device's smart error logs, if any.
If SMART shows no issues, then it's probably not "media" issues (ie bad NAND cells.)  Corruption might have been caused by a firmware issue; flash drives have often seen many firmware revisions, so check for updated firmware for your drive.
To answer your original question: yes, you can run badblocks (or similar) on an SSD.
Answer: First make a backup of any important data on the drive.
You can check the output of smart, it should report things like reallocated sector count, wear levelling count, program fail count, erase fail count, uncorrectable error count and so on.
The manufacturer of your ssd probably has some more specific drive test software which might give you more data.
Do you know exactly which files are corrupt? Is there any pattern to it (only newly written files? only old files? random? if you download a large file (maybe some Linux install cd/dvd image), and calculate it's checksum does it match the checksum posted on the dl page?)?
If none of these give anything conclusive, there are more destructive methods of testing. They do have a few drawbacks. First, they will destroy  any data currently on the drive, second, some can be very slow, third, some will use up some of the limited amount of writes each drive has (shouldn't be that big of a problem for most new drives, but still). I'd use the manufacturers sw to reset the drive (clears out all cells, making it appear as a new drive), run badblocks (the destructive write test), reset the drive again, put a few files with known checksums on the drive, and compare the checksums.
You might as well test your memory and cpu before going for the destructive tests since memory/cpu errors can also corrupt files, but the tests don't destroy any data and don't really cause much wear on your hw.
If you fail during any of the tests, post where and with what error, if not then the drive seems fine, although I would still keep an eye on it using smart, creating checksums of all files on it and comparing them every so often for any changes that shouldn't be there.


Binomial identity in Riordan's Combinatorial Identities

Question: I am reading Riordan's Combinatorial Identities. On page 8 there is a formula like screenshot. I have no problem to understand the first three lines, in which we use $(-1)^m \cdot \binom{-n}{m} = \binom{n + m - 1 }{m}$ twice and Vandemonde identity in between. I could not understand the last step.
Answer: I was stuck for a while then I realize I can just replace $m-k$ with $u$ and last step comes naturally from the previous step:
$$
\binom{p}{u} \cdot \binom{n-u}{m-u}
$$
The power of $-1$ becomes $(-1)^{u+2k} = (-1)^u$. Eventually rename $u$ with dummy variable $k$.
Answer: Note: It is helpful to use indices with lower and upper limit to clarify aspects of this kind.

We obtain
\begin{align*}
\color{blue}{\binom{n-p}{m}}&=(-1)^m\binom{p-n+m-1}{m}\tag{1}\\
&=(-1)^m\sum_{k=0}^m\binom{p}{m-k}\binom{-n+m-1}{k}\tag{2}\\
&=\sum_{k=0}^m\binom{p}{m-k}\binom{n-m+k}{k}(-1)^{m+k}\tag{3}\\
&\color{blue}{=\sum_{k=0}^m\binom{p}{k}\binom{n-k}{m-k}(-1)^k}\tag{4}
\end{align*}
and the claim follows according to your analysis and as indicated in the comment below.
Comment:

In (1) we use the binomial identity $\binom{p}{q}=\binom{-p+q-1}{q}(-1)^q$.

In (2) we apply Vandermonde's Identity*.

In (3) we use again the binomial identity from (1).

In (4) we shift the index $k\to m-k$.


Backward jerk in Earth's frame?

Question: When the bus starts suddenly it accelerates and we experience a backward jolt, now since the Earth is continuously accelerating through space time why don't we experience that jolt here on earth itself?
Answer: Acceleration can be defined as a rate of change in velocity per unit time.  Velocity is a vector, which consists of both direction and magnitude.  Change of either will result in acceleration.
Because the Earth rotates on its axis and follows a curved trajectory around the Sun, it continually undergoes a change of direction type of acceleration. The magnitude of the Earth's velocity vector (speed) remains roughly constant, but the direction of the velocity vector changes constantly.
Our natural tendency is to fly off in a straight line into space as the surface of the Earth rotates away from under us.  This tendency (measured from the Earth's rotating inertial frame of reference) is called centrifugal force.  But we don't feel any acceleration from that centrifugal force, as it's the Earth that accelerates away from us, rather than we accelerating away from the Earth.  What we do feel is the centripetal force that keeps our inertia from carrying us away from the Earth, as the Earth accelerates away from us.
Gravity keeps us tethered to the surface of the Earth.  Gravity provides the centripetal force that keeps us from flying into space as the Earth accelerates away from us.  Our weight is the feeling we have from the centripetal force of the Earth's gravity which keeps us from continuing in a straight line away from the rotating Earth.
If the Earth's acceleration suddenly were to change, we would feel a jolt.  If the rate of spin changed appreciably, for example, even gravity might not be able to keep us from sliding backwards or forwards, or even off the planet entirely.  We have grown used to the steady directional acceleration of the Earth, and to the centripetal force that tethers us to the Earth's surface, so we don't notice it.
Answer: Well, it's just that the centripetal acceleration is not that big. If you take the acceleration to be
$$
a_{centrip} = r\omega^2
$$
and plug in various numbers, you get that the centripetal acceleration from Earth's rotation around itself is 0.3% of the gravitational acceleration and the acceleration from Earth's rotation around the sun is 0.06% of the gravitational acceleration.
Answer: There are two causes of acceleration: 1) change in speed, and 2) change in direction. Only the first type results in the jerk you describe. The accelerations we experience on Earth"s surface are the second type.  We feel them as small decrement in our weight compared to what we would weigh if the Earth were neither spinning nor rotating in its orbit about the sun. Since this decrement is relatively constant, we feel no jerk
Comment: @SarthakSharma : The accelerating expansion of the Universe is discernible only on vast cosmic scales (tens of millions of light years).  At scales less than that, gravity is the dominant force.  Astrophysicists ignore the effect of dark energy at small scales.  For example, our Sun burns millions of tons of hydrogen fuel per second.  Compared to that, the dilution of solar mass by expansion of the Universe, which should be apparent as a weakening of the Sun's gravitation field,  is un-noticeable.
Comment: See but earth also is in solar system which is moving blazingly fast through space and then solar system is in milky way which is moving extra blazingly fast so that affects the jolt ???
Comment: @SarthakSharma : "Blazing fast" velocity is NOT acceleration. Acceleration is a CHANGE of velocity.  Speed alone doesn't produce a jolt.  Only when speed changes, do you feel a jolt.  As the Earth's speed through space does not change, we feel no jolt, and as the Earth's rate of change of trajectory is constant and continuous, we grow used to it and don't notice it because gravity tethers us to the planet.
Comment: @Ernie Sorry for that blazingly fast term, I thought that earth is accelerating through space time, what about dark energy it makes space expand at an accelerating rate so does it mess up with  the speed of earth too?
Answer: The jolt or jerk (a technical term!) which you experience is caused by a sudden change in acceleration. When the bus starts moving it changes from zero acceleration to some positive acceleration. Even if the speed has not changed much, there is a sudden increase in acceleration. The same happens when you brake and the vehicle stops with a jolt.
The Earth is accelerating constantly round the Sun, and we are accelerating constantly as it rotates. In neither of these cases is there any sudden change in acceleration. There is no jerk.
See also :
Why does one experience a short pull in the wrong direction when a vehicle stops?
Bidirectional jerk motion on a stopping vehicle
How to brake 'beautifully'?

Backward jerk in Earth's frame?


How can I automatically rotate a picture?

Question: apparently Drupal 7's built in image handling doesn't automatically rotate images based. Is there an option to do that?
If not, how can I make it easy for a user to rotate an image left or right?
Answer: ImageCache Actions seems to provide an "autorotate" feature. If server has  Exif PHP extension enabled, and user's camera saved orientation in EXIF data, it automatically rotates image correct side up.
Comment: Added some minor information to answer.
Answer: In Drupal 7 the rotation feature is in Configuration > Media > Image Styles. Then in configuration of your image field, you can chose the style related.
to see image rotated, you must asign the style in the Manage Display tab of fields of your Content Type.
I hope information be useful.
Comment: that would rotate every image? I want the user to be able to decide if they want to rotate the image and if they want to rotate right or left. Thanks.
Comment: You can use Conditional Fields Module http://drupal.org/project/conditional_fields to allow to users choice between fields pre-configured (left or right), or use `drupal_process_states()` that `adds JavaScript to change the state of an element based on another element`. http://api.drupal.org/api/drupal/includes--common.inc/function/drupal_process_states/7


Differences between Raspbian Jessie and Raspbian Jessie Lite

Question: What are the differences between Raspbian Jessie and Raspbian Jessie Lite?
What's better for a Owncloud server: Raspbian Jessie or Raspbian Jessie Lite?
Answer: If I understand this and that right, the lite distribution is just a Minimal image based on Debian Jessie without the X-server and its components installed. Meaning it uses less space on the SD-card and can run from a smaller SD card. Installing the minimal image will also reduce traffic during updates (as pointed out by Jacob). Any desired package can still be installed by apt-get.
Technically, Jessie Lite should suffice to run an ownCloud server.

The MagPi, Issue 56, put it this way:

Lite is a minimal version of the Raspbian image for the
  Raspberry Pi. This means it has less software installed
  on it, and fewer modules will load with the kernel,
  which results in the operating system using a lot less of
  the Raspberry Pi's resources. It will use less electricity
  this way and perform a little faster for very specific
  tasks, such as file servers or other uses where it never
  needs to use a monitor.
Comment: If it's a headless server, I would recommend the lite version. Updating will use less traffic and IO, and may save space on logging as well as binary storage.
Comment: Jessie-Lite is the ultimate OS for a headless Pi, I still prefer Wheezy, but Wheezy isn't compatible with the latest Pi.
Comment: Arch is as ultimate an OS as any ;) But *Each must live as he sees fit.*, or as *Frederick the Great* has put it: *Jeder soll nach seiner Façon selig werden.*
Comment: Why isn't it compatible with the Zero?  Note that the kernel and the userland are distinct.  You can use whatever kernel you want with wheezy, you just have to install it (which `raspi-update` will probably do).
Comment: @PatrickCook I'm extremely dubious that "Wheezy" isn't compatible with the latest pi.  Which one?  I've run it on B/B+/2 at some point.  Not that I want to encourage people to stay stuck in the past...jessie is generally an improvement.
Comment: @goldilocks I was referring to the Pi Zero.
Comment: @patrickcook, that simply isn't true. I am running a web server on a Pi3 that uses wheezy. It runs just fine.
Comment: @PiGuy88 From https://learn.adafruit.com/introducing-the-raspberry-pi-zero/setting-up-your-sd-card : "Raspbian Wheezy 5-15 or earlier do not support the Zero! Try Jessie instead" I was referring to the pi zero. I already stated that above.
Answer: The lite version doesn't have a GUI(Graphical User Interface).
Comment: @CarlSmith: yes
Comment: Is it correct that you can still use a monitor and keyboard, just without a GUI?
Answer: Size-wise lite is 1GB smaller (300MB vs 1.32GB)
Comment: For lite 300MB is the (approx) size of the *compressed* image. It's more useful to know the actual image size which is 1.3GB for 2017-04-10-raspbian-jessie-lite.img. I don't have a copy of Jessie with PIXEL, but it [looks like](https://www.raspberrypi.org/downloads/raspbian/) it's over 4GB


Writing a short story set in a place I've never been

Question: I'm writing a science fiction type short story set in Germany (actually Stuttgart). To some extent the location isn't that important- it could be set anywhere but setting it there appeals to me and gives  the story a unique aspect. As someone who doesn't know German and have only briefly visited that part of the country,  how detrimental would that be when writing about the characters and their thoughts and dialogue? I guess I'll be writing as an English native and not German - does that matter in the context of the story?
Answer: You are writing in English, your characters are going to speak English, but that is in fact a "translation convention", your characters "in reality" speaking German instead. Is that the issue you're asking about?
Such situations are in fact very common in writing. Consider a book translated from German to English - the situation would be just the same as you describe. And many books are written from the start just as you describe. For example, Jules Verne's Les Enfants du capitaine Grant is a book written in French about a Scottish family.
What would be jarring is if your characters start using turns of phrase that are very location-specific: 'Megabucks' would only be used in America, 'lass' is most commonly used in Scotland, etc. When you use such words, your story says 'Germany', but the language says something else.
I guess it is possible for a way of thinking, a way of responding to a situation, to be "very American", "not how a German would respond". Cultural differences do exist. You should do your research about this - talk to someone from Germany, read about Germany. This shouldn't stop you from writing, though. End of the day, people are people, and globalisation makes us more and more alike.
Comment: Thanks for that- that's s pretty much how I am going to approach the writing, with a view to keeping out any English colloquialisms.
Comment: @auburg: There are lots of YouTube videos about the differences between America and Germany, mostly by Americans that live or have lived in Germany. That might be a great starting point for your research of cultural differences.

Writing a short story set in a place I’ve never been


All my iMessages were deleted

Question: My iPod Touch ran out of battery and died for a short time. When I plugged it back in and it turned back on, all of my conversations on iMessage had been deleted. I still have the contacts but all of my texts and messages were gone. Why did this happen and is there any way to get my messages back?
Comment: Restore from a backup
Answer: Reboot your phone.
I discovered a solution for this one accidentally, after I encountered this bug a couple of days ago. I turned my phone off for a time, and then back on again - when it was turned back on, the list of messages was fully restored. I think that this might be because only the listing of messages was made inaccessible, and the messages themselves weren't deleted - I noticed that when I was texted by someone who I'd received messages from in the past, the message history was properly displayed once I opened the text conversation with them.
It's possible that the simplicity of fixing this issue is why Apple hasn't patched the bug in the 5+ years it's been known about.
Answer: There ( sorry ) Is no possible way to get your messages back. The reason is is probably because your iPod was corrupt or not up to date. Simply contact an apple store and turn your Pod in, and they should give u a replacement while they check for a virus. Other reason may be because someone sent u a corrupt picture, long text, or virus text while your phone was off. Update your iPhone ( Software update ) and it'll never happen again.
Comment: Please provide a source for your claims. To my knowledge iMessages are stored on iCloud servers. What viruses are there for iPods?

All my iMessages were deleted


If heat causes the magnet to lose its properties, how it is possible that the Sun has a magnetic field

Question: If heat causes the magnet to lose its properties, how it is possible that the Sun
has a magnetic field.
Comment: Not all magnets are the same. Not all magnetic fields come from magnets.
Comment: If heat causes *some* magnets to demagnetize, how come other, vastly different magnets behave different, you mean?
Comment: Related, effective duplicate imo: https://physics.stackexchange.com/questions/65335/how-do-moving-charges-produce-magnetic-fields
Answer: The magnetic field of the Sun has a different origin from the magnetic field of the magnets we all played with as children.
Magnets owe their magnetic field to a phenomenon called ferromagnetism. Electrons have an intrinsic magnetic field i.e. every electron behaves like a tiny bar magnet. In ferromagnets the unpaired electrons line up so their intrinsic magnetic fields reinforce each other and produce the large magnetic field of the magnet.
However the thermal vibrations in the magnet jostle these electrons, and if you heat the magnet to above a transition temperature called the Curie temperature the jostling becomes so great that it knocks the electrons out of alignment and the overall magnetic field disappears. The magnetism hasn't disappeared - it has just become randomised.
In contrast the magnetic field of the Sun is due to the currents inside. Any moving charge generates a magnetic field, and since the Sun is made of plasma there are lots of moving charges in it. The Sun's magnetic field is generated by the large scale flows of the plasma within it. These flows are driven by temperature differences, so in fact the Sun owes its magnetic field to its high temperature.
You don't have to go as far as the Sun to see this, because the same happens in the Earth's core. The temperature gradient from the centre to the outside of the core causes convection currents and this motion generates the Earth's magnetic field. This happens even though the temperature of the core is well above the Curie temperature.


iPad app, HTML5, rotating for landscape and portrait

Question: If an iPad app basically hosts Webviews, and within those webviews I load some html5 docs, would there be an issue with rotating the device and rendering the UI in both landscape and portrait?
By issues I means the HTML5 do I have to do any special handling for it as I rotate the webview? should I build two html docs one for portrait and one for landscape mode? and if so does that mean when rotating I have to load one into the webview and pause the UI until that is done?
Answer: UIWebView is a subclass of UIResponder -- from which you can capture motion events such as tilting/rotating. So assuming you find trouble with your code down the track, you can do something about it
You can also use UIDevice to get more information about the device's orientation


Maximum Symmetrical Swing for BJT Amplifier

Question: I am doing the DC analysis for a BJT amplifier using the 2N3904 transistor in a common emitter configuration.  I am given +Vcc = 18V and need to find Rc to give maximum symmetrical swing.  From my research I see to choose a value for Ic and then find Rc such that Rc = (+Vcc/2)/Ic.  In this way the voltage at the collector i.e. Vc = +Vcc/2.  However, I saw a different design which said to find Rc using Rc = ((+Vcc - V_Re)/2)/Ic where V_Re is chosen as 1V.  The former approach makes more sense to me. Looking for guidance as to which way is better.
Comment: Is this to be an AC amplifier? Will it have an Emitter resistor for bias stability, and will it be bypassed to AC?
Comment: Using the term "symmetrical" suggests low distortion and flat gain. By definition, this means minimal swing at the output, not maximal. The reason is that large swings imply large changes in collector current, implying large changes in dynamic emitter resistance. Compensating that means low gain. Etc. Maximum and symmetrical are opposing terms. You'll need to specify a compromise.
Comment: It is more of a thinking question than one with a specific answer. Ignoring saturation say your CE amp pulls the output from Vcc/2 to ground (0V); namely doubling its collector current. What happens on the other half cycle of the input signal? The collector current drops to 1/2 of its quiescent point, so the output only rises to 3/4 Vcc. Ignoring distortion, solving for the largest output swing is some what complicated.
Answer: Your approach ignores the fact that the minimum voltage that you can get at the output is not zero, whereas the approach you found takes that into account.
In other words, your simplified approach would result in a circuit that clips the negative peaks before the positive peaks reach their limit, reducing the symmetrical swing from the maximum possible value.
Comment: I think I understand what you are trying to say. Correct me if I am wrong, but you are saying that with R_E in the circuit, V_CE cannot drop to zero. Now lets ignore the load, when Icc = 0 i.e. at cutoff, and assuming Ic = Ie, then V_CE = +Vcc.  Then we need to look at the other end of the spectrum i.e. at saturation when Ic is at maximum.  I am assuming that when Ic is at max, that V_CE = V_Re and not zero as would be the case if R_E was not in the circuit. Now is there any equation to show V_CE = V_Re when Ic is at max?
Comment: Note that at all times, \$V_C = V_{CE} + V_E\$. Also, \$V_E\$ rises with emitter current and \$V_{CE}\$ never gets all the way to zero -- 200 mV is a fairly typical minimum value.
Comment: Ok just to confirm I understand everything, I should be looking at the limits of the output and this is given by Vo = Vc = V_CE + V_E. So when at cutoff, i.e. Ic = 0, Vo = Vc = V_CE = +Vcc (upper limit) since V_E = I_E*R_E and since I_E is approximately Ic then V_E = 0. Now at saturation, V_CE = 0, assuming that V_E remains constant according to its DC bias value (due to the presence of a bypass capacitor acting as short to an AC variation), then Vo = Vc = V_E = IcqRe.  Therefore my upper limit for my output becomes +Vcc and the lower limit is V_E and I should center on this range.
Comment: Note that you never said that the emitter resistor is bypassed in your question. But if that's the case, then yes, the emitter voltage remains essentially constant for frequencies above the bypass cutoff frequency.
Comment: Ok, thank you very much for the advice. It helped me to understand a lot of key concepts I was missing.
Comment: This is the actual question: If the load is connected between Vc and GND, why would the minimum voltage be non zero. To me it should be zero. Could you explain why?
Comment: What is the voltage on the collector at transistor cutoff? (Note: As James says, this can be influenced by the load resistance.) What is the voltage when it is saturated? Those are the two extremes you want to center on. Remember, when the transistor is approaching saturation, the current between collector and emitter is significant, and you can't ignore the voltage drops across any resistor(s) through which this current is flowing.
Answer: If there is no load resistor, it makes sense to bias the collector half way between Vcc (18V) and Ve (1v in your case) for maximum collector swing in either direction. This is because, with no load resistor, the limits of the collector swing are 18V and about Ve+0.2V. (assuming the signal wiggle on the base is quite small).
In the more practical situation where the collector is coupled to a load resistance via an ac coupling capacitor it makes more sense to bias the collector to Vcc/2 = 9V for maximum collector swing in either direction. It depends on the relative values of collector resistance and load resistance but in the limit when the transistor is switched off the collector will not swing right up to 18V because it is in the middle of a potential divider formed by the collector resistance and the load resistance. If Ve is 1V and the maximum positive going excursion of the collector is, say 17V then it makes sense to bias the collector to Vcc/2 = 9V.
Comment: Eventually the load resistor will be included, the only reason it is not included is so that I can set up max symmetrical swing so that my both the negative and positive portion of the output is clipped at the same level. Therefore based on what you said I should bias my collector to Vcc/2 since the load is connected between Vc and GND. I am correct about this?
Comment: Also what do you mean by the collector swing. Is that Vce and V_Rc?


How do I use the timers on an Arduino Uno R3?

Question: I want to make a simple circuit which returns the time/delay between two, consecutive loud sounds (i.e, a mic reading of ~600) coming from a speaker. I have set up and ADMP 401 microphone for this purpose. How do I measure the time it takes for this application?
Comment: Do you know how to wire up and detect the sound from the microphone using the Arduino?
Comment: Why can't you use `millis()` for this?
Comment: What is the time precision you need?
Comment: @jippie: yes, I have done so successfully
Comment: @jfpoilpret: I need time precision of the order of 10^-6 secs. Of course, smaller is better :)
Comment: 1us precision is about the best you could get on Arduino UNO. But any instruction executed will probably have an impact on that precision. Your best option is probably to use `attachInterrupt()` but it requires you to first change the electronics so that it converts the mic analog signal to a logical signal (you can use an AOP for that) that is connected to a pin that will trigger the interrupt.
Comment: 1us may be impossible to reach as it leads to 1MHz frequency; audible sounds are limited to ~20KHz only; I don't even think your mike could react that fast!
Comment: Can you elaborate on the mic's analog -> logical signal? And what is an AOP?

IMO, you should post it as an answer instead :)
Comment: and ah, good point about the 20 KHz signal. That's where experimentation comes in.
Comment: Sorry no time for an answer right now (must go to work...). I'll do it tonight if it's not answered yet. By AOP, I meant op-amp (Operational Amplificator); sorry that was the french abbreviation :-(
Comment: You may want to investigate using ICP on timer 1 for lowest possible latency.
Answer: Your question is probably not as simple as it may seem.
One approach I would use if I was to address this same problem would consist in:

converting the analog output of the mike into a digital value (based on a threshold to determine)
connect this digital signal to one Arduino pin that can trigger an interrupt when its level changes

Let's first start with the easy part: Arduino program.
Let's say we have a digital signal that raises to 1 as soon as a sound of too high amplitude is captured by the mike; it shall stay 1 as long as the sound does not reduce amplitude enough. We will connect this signal to Arduino pin 3; then we can use attachInterrupt() to have a function called whenever this pon level raises to 1:
volatile static bool started = false;
volatile static unsigned long timing = 0;
volatile static bool finished = false;

void loud() {
    if (started) {
        timing = micros() - timing;
        started = false;
        finished = true;
    } else {
        timing = micros();
        started = true;
        finished = false;
    }
}

void setup() {
    pinMode(3, INPUT);
    attachInterrupt(1, loud, RAISE);
}

void loop() {
    if (finished) {
        // Do something with timing
    }
}

Now the hardest part: electronics!
A first issue we have to deal with is related to the fact that the raw mike signal will have same wave shape as the sound it captures, this wave has a frequency that can vary between 10Hz (bass) and 20KHz (treble).
Indeed, if we convert the mike analog output to a logical value (1 when the analog value is above a threshold we'll call Vt, 0 when it is under Vt) fast enough, then, if the environmental sound as an amplitude above Vt, the logical input connected to your Arduino will oscillate at the same frequency as the sound! This would make our efforts pointless as you would measure the period of the sound wave instead of the elapsed time between two distinct sound bursts.
That means that we should probably first "smoothen" the analog sound signal in order to avoid disturbance of its frequency.
Hence point 1 will have to deal with these 2 aspects:

smoothen analog input value
compare smoothened value with Vt threshold and provide a logical value from this comparison

Comparison can rather easily be performed by an op-amp used as a comparator.
However, the main difficulty you may have with an op-amp is the need for a symetric voltage supply (e.g. +5V/-5V) although it is possible to use a single supply but that raises further limitations (outside the scope of my answer).
Smoothening the signal is potentially more complex, although it can be done with a simple capacitor, because smoothening the signal generally means weakening it, thus you would lose the initial amplitude of the sound signal.
So how can we deal with that?
A Schmitt trigger is probably a good solution for this problem but further experiment will be needed to confirm that.
Comment: Thanks for the answer. Well the ADMP 401 already has an amp of sorts, so is a separate op-amp required? Would an op amp like this one work: http://www.protocentral.com/breakout-boards/136-mono-audio-amp-breakout-tpa2005d1.html?search_query=op+amp&results=22 ?
Comment: The ADMP 401 uses an Op Amp as a signal amplifier not as a comparator, so you will still need an additional Op Amp mounted as a comparator. There are plenty of Op Amps available and cheap; I think the LM 358 chip (https://www.sparkfun.com/products/9456) should fit your purpose; this one only requires a single supply (between 3V and 32V).
Answer: When you mentions "loud sounds (i.e, a mic reading of ~600)" I'm guessing that means you've successfully connected the mic to an ADC input and you are referring to analog readings, right?  (If not you may need to clarify).  I won't worry about scaling or offset biasing the inputs, assuming you have that part down and you can test the Analog input to detect loudness.
If your Arduino can be dedicated to making this measurement (ie: doesn't need to do anything else while doing it), then the simplest solution might be a loop comparing the ADC input with some threshold you have determined, and using micros() to check the time different.  The micros() function has only 4 uS resolution, but the loop time will add more time than that anyway, and actually the limited bandwidth of your audio signals (speaker and mic both) will make any microsecond level measurement suspect anyway.  So the simple loop might be as accurate as you need.
For example:
const int THRESHOLD = 600; // adjust
const int MINDELAY = 1000;  // adjust

long
takeMeasurement() {
    while(analogRead(A4) < THRESHOLD); // wait for first trigger
    long start = micros();
    delayMicroseconds(MINDELAY); // let first noise die down
    while(analogRead(A4) < THRESHOLD); // wait for second trigger
    return micros() - start;
}

You would call this function when you were ready to take a measurement.  To keep the loop time short (when it's waiting for a loud sound), it has no timeout, so it won't return until it does detect two loud sounds.  Depending on your need, you might need to change that and have an escape from the loops.  There are several ways that might be done:

test for micros() exceeding some timeout within the loop
decrement a counter in the loop and exit if it goes to zero (or if the sound is detected)
test a flag (volatile byte) in the loop, which gets set by a timer interrrupt

Which is best depends on other aspects of your overall design.
Comment: Yes, that is correct, I'll try this out the next time I start messing with my arduino :)