How to remove the option to boot from Ubuntu in the Windows Boot loader?

Question: An year and a half ago, I installed Ubuntu on my computer using Wubi. After a while I decided to install Ubuntu on a separate partition. So I uninstalled the Ubuntu using Wubi, and installed Ubuntu on a separate partition by booting from the Ubuntu ISO.
Though Wubi uninstalled Ubuntu from my Windows partition it did not remove the option in the boot menu. So now when I boot, the grub menu has option for Windows and Ubuntu, but if I choose Windows from the menu, I again get two options - Windows and Ubuntu, this time from the Windows boot loader. If I choose Ubuntu, it just shows and error asks to go back.
So how do I remove the option?
EDIT:  I have tried to use bcdedit but it did not help.
If I run bcdedit on the command prompt, this is the output:
Windows Boot Manager
--------------------
identifier              {9dea862c-5cdd-4e70-acc1-f32b344d4795}
device                  partition=V:
path                    \bootmgr
description             Windows Boot Manager
locale                  en-US
default                 {e58e9c4c-dc5b-11e1-be69-bb3b6bb64ef4}
displayorder            {e58e9c4c-dc5b-11e1-be69-bb3b6bb64ef4}
bootsequence            {b2721d73-1db4-4c62-bf78-c548a880142d}
timeout                 3

Windows Boot Loader
-------------------
identifier              {e58e9c4c-dc5b-11e1-be69-bb3b6bb64ef4}
device                  partition=C:
path                    \WINDOWS\system32\winload.exe
description             Windows 7 Ultimate (recovered)
locale                  en-US
recoverysequence        {e58e9c4d-dc5b-11e1-be69-bb3b6bb64ef4}
recoveryenabled         Yes
osdevice                partition=C:
systemroot              \WINDOWS

According to this I should only have one entry which should be named Windows 7 Ultimate (recovered) but instead when I boot I have two entries, one named Windows 7 and the other named Ubuntu. I couldn't find any answer by googling.
I also tried to set the timeout to 0, but again for no help, the boot screen still waits three seconds before selecting the default option.
Answer: Start menu > type 'msconfig' > within the 'boot' tab, remove the entry from there.
Comment: There is no entry there.


Is my interior door LH or RH?

Question: Have just read your 2010 posts regarding whether an interior door is LH or RH.  Using the "hand that plus the door toward you" guideline, I get the opposite of what I get when using the hinge/jamb guideline. I do in fact have 3 interior doors that pull toward me using right hand but using the jamb guideline, they are LH. I would call these outswing as they do not swing  IN to the area they are closing. I have another door into a small bath I would call inswing RH using the jamb guideline but LH using the left hand to pull towards me. I'm starting to like the idea to take a drawing with me...
Answer: Stand in front of the door.

If the handle moves away from you and to the left, it's left handed.
If  the handle moves toward you and to the right, it's left handed.
If the handle moves away from you and to the right, it's right handed.
If the handle moves toward you and to the left, it's right handed.

Basically, if it opens away from you, it's whichever way it opens to. If it opens toward you, it's the opposite of whichever way it opens.
Answer: How about this,
when you pull the door open, where is the knob.
on the left, it's a left
on the right, it's a right
Comment: This is a LOT easier to remember!

Is my interior door LH or RH?


approximate a square function with a linear one

Question: I have to code a function in matlab (F1) whose values range from 0.740261423849103 to some where around 0.95. Then there is another function (F2) which is usually the square of F1. Is there any way I can replace F2 [ which is F1^2] by a linear form such as K*F1 so that F2 approximates F1 utilizing the fact that F1 lies between 0.74 to 0.95? If I need to put in different values of K for different ranges of F1 that would also be ok. I need to approximate few other complex expressions by simpler linear ones so is there any method I can follow to determine what would be the best approximation? As I mentioned, it would be feasible for me to use different values of K for different ranges of F1.
Answer: You can do this with a piecewise linear function.


Should I buy Coda 2 on the app store or directly from Panic?

Question: I'm very interested in buying Coda 2 (a web development IDE) when it comes out on the 24th. My concern is that the App Store version will have less features than the non-App Store version. Will Apple's new sandboxing policies be likely to limit the use of an application like Coda? Is there any reason to not buy direct from the developer?
Comment: We can't speculate on such things (the features that will or won't be in either version). Your best bet is to wait for the release and see the differences. Panic, in my opinion has always be a pretty open straightforward company, if there are differences, they'll say it.
Answer: As you can read on the FAQ page of Coda, there is indeed a difference:

Should I buy from you directly, or from the Mac App Store?
It's largely a matter of personal preference. Please refer to the pricing FAQ above to see which way gets you the best price.
At the moment, there is only one difference between the two versions: the Mac App Store version will support iCloud syncing of Sites and Clips, and the direct version will not. This is a restriction imposed by Apple.
Apple often changes the conditions for Mac App Store eligibility, and it's possible we may have to modify or remove features from the Mac App Store version in the future. It's our intent to keep them as close to identical as Apple will let us.

So there you have your answer.
So, if you like to sync with iCloud, you should buy from the Mac App Store.
If you like to have a 50% discount, buy from Panic directly!
I would go for the 50% discount. :)
Comment: Just to clarify - there is no pricing difference at launch between an upgrade price, the mac app store price and the direct download and pay Panic price. In this case (no upgrade) Panic has mentioned that both methods will be priced the same.
Answer: I would buy directly from Panic (and have):

All the profit goes to them (no 30% Apple cut).
The App Store does not allow for upgrade pricing (discounts on upgraded licenses).

It is the last one that most concerns me.  I bought Cornerstone (svn client) from Zennaware directly for those reasons.  They do give upgrade pricing, so it is well worth it.
Edit:
Turns out that panic does offer upgrade pricing, so thats a big point in favor of skipping the app store.
I just keep a dedicated folder in my email (and password keeper) for the license details, in case I have to reinstall.
Answer: This is a nice general problem to have and shows how many options developers are trying to see what strikes the best balance for them.
There are some real headaches involved on the developer and back end (store side) if Apple ever allows upgrade pricing so I wouldn't make any purchase assuming that a change there will come soon or ever.
I would always engage the developer (Panic in your case) to see what they say about the merits of a direct download and the app store model. As other answerers have pointed out - the App store places many restrictions on an application in terms of needing to be signed (for gatekeeper), not being able to run with administrator permissions, and having to live with sandboxing security constraints. On the other hand, the Mac App Store apps will be able to use iCloud document syncing exclusively, and over time more exclusive benefits may come to make those apps preferable to you.
The best solution I've seen is MarsEdit where you can either buy the program directly from the author's website or the store for the same price. However, in the interest of getting some bug fixes to end users before Apple can review them, the app store version of the app also enables you to run the downloaded versions of the apps without needing a separate license.
Not all developers have done this level of interoperability so do your research before assuming you can switch back or forth. To date, I don't know of any app that has allowed previous purchasers to convert to the paid app other than by announcing a short sale period where the app is offered for a discount or for free to all who wish to buy on the App Store.
Panic's model of pre-announcing the sale and pre-announcing the discounted prices and durations allows new users to benefit from a reduced price as well as accommodate users that may be in an "upgrade" scenario without being able to integrate this upgrade pricing while maintaining the full price point for non-upgraders.
In the end - it's about how you prefer to have your software licensed. The standard Mac App Store model is sometimes more lenient in the number of personal copies, but not as flexible for negotiating a bulk or upgrade special pricing at an arbitrary purchase time.
Answer: i chose to buy direct but i have not yet been able to install. the email and links Panic has sent to not seem to function at all. So Im stuck sitting here while app store downloads work fine.
Emailed support, no response.
Answer: Well, I bought from the App Store because you may choose after paying:
It says in the FAQ that after buying the MAS version you can switch do the "Direct" version by asking it to the support. BUT YOU CAN'T DO THE OPPOSITE.
PS - When I bought there was no 50% discount :( So you may want to consider that.
Answer: I bought on AppStore the first day and now I really want to update to 2.0.1 (v2 is not stable), the new version is available since the 4th but not on AppStore.
In my opinion, this is a big problem, if one day Apple make this own code editor, this is too long to validate app!
More here : http://www.panic.com/blog/2012/06/update-on-coda-2-0-1-mac-app-store-version/
Edit : now (21 th june) 2.0.1 available on AppStore
Answer: I would buy it straight from panic. That way, when updates are released you will be able to download them immediately without having to wait for the app store to approve the purchase.
More importantly, more of your money will be going directly to Panic instead of Apple. More money to Panic means more time and resources they can spend making Coda 2 better. Support the developer you like, not apple. Lastly, you can check for updates everytime you use Coda through the app instead of having to load up MAS to see when updates are released or subscribing to Panic's mailing list/visiting a version site like macupdate. This opinion might be a bit biased as I hate the mac app store, but the fact that you will get updates sooner and more of the money goes directly to Panic makes it a no brainer for me but this is the beauty of a developer who offers two methods of purchasing.
Answer: My Personal Take on it is, buy/download it directly. Its always nice to have that copy floating around for use later when its needed for whatever random reason, although you could just require it from the app store the same way. But the draw back to that is, you never know when apple is gonna say we don't want this product here anymore. Like its done with handfuls of apps in the past.
Also from the app store or directly I think you can use icloud regardless. I dont use icloud with coda as Ive to many sites to worry about that take up gigs upon gigs of space. but I remember when I bought Coda directly I was given the option to set it up with iCloud.
and theres my 2 cents..


Credit Card encryption techniques available and recommended libraries in java

Question: Looking for some great Java libraries to encrypt the credit card information. Also the available encryption techniques available.
Comment: This may be a suitable place to ask about Java encryption libraries (depending on the question) but not really the best place to ask about techniques and best practice. StackOverflow and SoftwareEngineering are probably more suitable for those questions.
Comment: You might want to store the whole CC number just until the bank accepts the charge, and then delete all but the last four digits, in order to  make your DB less of a target for hackers. Also, *never* store the 3 or 4-digit CVV after authorization has been accepted.
Answer: You may try jasypt

Jasypt is a java library which allows the developer to add basic
  encryption capabilities to his/her projects with minimum effort, and
  without the need of having deep knowledge on how cryptography works.


Which Quran verses mention the sahaba/companions?

Question: I am looking for verses in the Quran that mention the companions of the prophet Mohamed. Can anyone help me find these verses?
Comment: Do you mean by name? By name, only one companion is mentioned in whole of Qur'an. Zaid bin Harithah (radiyallahu 'anhu) in 37th Verse of Surah al-Ahzaab.
Answer: Yes zaid is the one mentioned in Quran. Have a read at this ayah

**وَإِذْ تَقُولُ لِلَّذِي أَنْعَمَ اللَّهُ عَلَيْهِ  وَأَنْعَمْتَ عَلَيْهِ أَمْسِكْ عَلَيْكَ زَوْجَكَ وَاتَّقِ اللَّهَ وَتُخْفِي فِي
  نَفْسِكَ مَا  اللَّهُ مُبْدِيهِ وَتَخْشَى النَّاسَ وَاللَّهُ أَحَقُّ
  أَن تَخْشَاهُ ۖ فَلَمَّا قَضَىٰ *زَيْدٌ مِّنْهَا وَطَرًا
  زَوَّجْنَاكَهَا لِكَيْ لَا يَكُونَ عَلَى الْمُؤْمِنِينَ حَرَجٌ فِي
  أَزْوَاجِ أَدْعِيَائِهِمْ إِذَا قَضَوْا مِنْهُنَّ وَطَرًا ۚ وَكَانَ
  أَمْرُ اللَّهِ مَفْعُولًا*
And [remember, O Muhammad], when you said to the one on whom Allah
  bestowed favor and you bestowed favor, "Keep your wife and fear
  Allah," while you concealed within yourself that which Allah is to
  disclose. And you feared the people, while Allah has more right that
  you fear Him. So when Zayd had no longer any need for her, We
  married her to you in order that there not be upon the believers any
  discomfort concerning the wives of their adopted sons when they no
  longer have need of them. And ever is the command of Allah
  accomplished.
Answer: By name, as the answer and comment above indicate, it was only Zaid (RA). Generally, all of them in this verse:

Muhammad is the Messenger of Allah ; and those with him are forceful against the disbelievers, merciful among themselves. You see them bowing and prostrating [in prayer], seeking bounty from Allah and [His] pleasure. Their mark is on their faces from the trace of prostration. That is their description in the Torah. And their description in the Gospel is as a plant which produces its offshoots and strengthens them so they grow firm and stand upon their stalks, delighting the sowers - so that Allah may enrage by them the disbelievers. Allah has promised those who believe and do righteous deeds among them forgiveness and a great reward.

(Holy Qur'an 48:29)
Answer: The verse 9:100 of the Quran is acknowledged as the strongest verse which praises the Muhajireen and the Ansaar Sahabas and declares that Allah is pleased with them due to their sacrifices for Islam. The suffix radiallahu Anhu also derived from this verse:

And the first forerunners [in the faith] among the Muhajireen and the Ansar and those who followed them with good conduct - Allah is pleased with them and they are pleased with Him, and He has prepared for them gardens beneath which rivers flow, wherein they will abide forever. That is the great attainment.
Answer: Asalam o AlieKum :
This story is mentioned in the Quran in SURAH TAUBA CH: 9 V Allah says:�
"If you will not aid him (the Prophet), Allah certainly aided him when those who disbelieved expelled him; he (the Prophet) had no more than him, him being the second of the two (i.e. Abu Bakr), when they were both in the cave, when he (the Prophet) said to his companion (Abu Bakr): 'Grieve not, surely Allah is with US.' Then Allah caused His Sakinah (serenity, peace, tranquility, etc.) to descend upon him (Abu Bakr)" (Quran, 9:40)
Sadaq ALLAH ul Azeem
Answer: Kindly also see this verse:
"Allah was well pleased with the believers when they swore allegiance unto thee beneath the tree, and He knew what was in their hearts, and He sent down peace of reassurance on them, and hath rewarded them with a near victory" [48:18]
Answer: As Salamo Alaikum Wa Rahmatullah Wa Barkatuhu
سورة الأنبياء Verse 101/102/103
سورة الفتح Verse 18/29
سورة التوبة Verse 40/100
Comment: Welcome to islam.stackexchange. It would be nice to either cite directly or to link, e.g. to https://tanzil.net/#9:40 to help finding the reference.
Answer: Assalamu Alaikum. There was an encounter of the Prophet (SAW) with Abdullah ibn Umm Maktum (RA) (Umm Maktum meaning mother of the concealed one as Abdullah (RA) was blind) that is mentioned in the Quran, however not by name. This is Surah Abasa (He frowned) which describes when the Prophet (SAW) was inviting Quraysh leaders to Islam and turned away from the blind companion who had asked him to recite from the Quran. Because of this, Allah (SWT) revealed the surah informing us how we should not treat people worse because of their standing in society.


Where can I find drivers for Windows 7 on an iMac without Boot Camp Assistant?

Question: I have OS X installed on my 27" iMac and want to dual boot with Windows 7. I installed rEFit and then installed Windows 7. Now I need the drivers that normally get installed with Boot Camp Assistant. Does anybody know where to find them? I can't find them on Apple's site.
Comment: For more recent BootCamp versions there's http://apple.stackexchange.com/questions/24118/how-to-download-bootcamp-drivers-without-bootcamp-assistant
Answer: They are on one of the installation disks that comes with your iMac. Also, I'm pretty sure the drivers get installed if you download and run a "Bootcamp Software Update for Windows"  from Apple's support site. They are usually 200MB or up downloads that come packed with drivers for windows, so give it a try in case you can't find your cds.
Comment: I found them on the Apple Disc, but the software updater did not work! :)
Comment: It would be nice with a download though, but i dont think it exists
Comment: Well, the link I posted takes you to the download in Apple's support page :) I suggest you give it a try :P
Answer: They should be on the installer file for Windows that is linked on this Apple Support article. If your Windows is 64-bit, then check out this article. Hope this helps.


What does it mean when your destination airport is currently "below IFR minimums"?

Question: Does it mean that absolutely nobody can land there until conditions improve? Can ATC still give you an IFR clearance to your destination airport in this case?
Comment: @Notts90 I don't understand this comment - airports absolute do get closed or at least stop receiving traffic. If the airport can't cater for the IFR minimums required then nobody lands there - simple.
Comment: @Dan It's not that simple. I've landed many times, legally, in Part 91 operations when the airport was below minimums. Whether an airport is below minimums is determined by what instruments on the ground are reporting, not what the pilot sees. Under Part 91 you are allowed to fly an approach regardless of what those instruments are reporting. Whether you can legally land or not depends on what you see when you reach the MDA or DH, and you can often see approach lighting even though the airport is below minimums. This is especially true at night.
Comment: @Terry No doubt, maybe I've misread but I interpreted Notts comment as surprise that there may be times where no landings are possible.
Comment: @Dan I will try and be clearer next time as that's not what I meant. I know an airport can be shut. The way I read the question was as if it was implying an airport was permanently below IFR minimums and therefore no one could ever land there.
Comment: @Notts90 Gotchya!
Answer: It would be very helpful to know where you read or heard the phrase, to get some context. But, it likely means that weather conditions at the airport are below the IFR takeoff minimums in 14 CFR 91.175:

(f) Civil airport takeoff minimums. This paragraph applies to persons
  operating an aircraft under part 121, 125, 129, or 135 of this
  chapter.
(1) Unless otherwise authorized by the FAA, no pilot may takeoff from
  a civil airport under IFR unless the weather conditions at time of
  takeoff are at or above the weather minimums for IFR takeoff
  prescribed for that airport under part 97 of this chapter.
(2) If takeoff weather minimums are not prescribed under part 97 of
  this chapter for a particular airport, the following weather minimums
  apply to takeoffs under IFR:
(i) For aircraft, other than helicopters, having two engines or less—1
  statute mile visibility.
(ii) For aircraft having more than two engines— 1⁄2 statute mile
  visibility.
(iii) For helicopters— 1⁄2 statute mile visibility.

Landing minimums are per-approach so it wouldn't make sense to say that the whole airport is below IFR minimums based on landing criteria. However, without reading or hearing the phrase in context, I may be wrong.
As for landing there anyway, even in zero visibility a private pilot operating under part 91 is free to take off, or to start an instrument approach. You can't legally land if visibility is below the approach requirements, but you can still fly the approach to 'take a look'. It might not always be smart, but it's legal.
On the other hand, commercial flights under part 135 or 121 can't even start an approach unless conditions are above certain minimums (e.g. see 135.225(a)). Those minimums are usually just the ones required for the particular approach, but they can also have operator-specific requirements. Of course, many commercial aircraft have crew and technical capabilities that light aircraft don't (like shooting a CAT III ILS), so they might still have a better chance of landing in marginal conditions.
Comment: Take-off minima of a *destination* airport don't seem particularly relevant, so I am inclined to think it simply means it is below minima of its best approach. I agree it would deserve clarification.
Comment: There is additional complication that even if there is, say, CAT III approach, it can only be used as CAT III if the plane is certified for it and the crew is current, which is far from granted even for airline flights.
Answer: I think they are referring to the minimum visibility and ceiling that is required. There are two cases. Actually landing at an airport and filing an IFR flight plan.
Per §91.175   Takeoff and landing under IFR.

(c) Operation below DA/DH or MDA. Except as provided in §91.176 of
  this chapter, where a DA/DH or MDA is applicable, no pilot may operate
  an aircraft, except a military aircraft of the United States, below
  the authorized MDA or continue an approach below the authorized DA/DH
  unless—
(2) The flight visibility is not less than the visibility prescribed
  in the standard instrument approach being used; and

Part 91 aircraft may attempt an approach if visibility is reported to be below minimums, but Part 121 and 135 may not begin the approach if reported visibility is below minimums. Effectively, the airport is closed to them.
You may file to an airport that is expected to be below minimums at the time of arrival, but you must file an alternate that is above IFR minimums. §91.169   IFR flight plan: Information required. has details.

(c) IFR alternate airport weather minima. Unless otherwise authorized
  by the Administrator, no person may include an alternate airport in an
  IFR flight plan unless appropriate weather reports or weather
  forecasts, or a combination of them, indicate that, at the estimated
  time of arrival at the alternate airport, the ceiling and visibility
  at that airport will be at or above the following weather minima:
(A) For a precision approach procedure. Ceiling 600 feet and
  visibility 2 statute miles.
(B) For a nonprecision approach procedure. Ceiling 800 feet and
  visibility 2 statute miles.

So yes, ATC can give you a clearance to an airport that is below IFR minimums.
Answer: You can still get clearance to the destination, at your discretion. It's not unheard of for weather conditions to be below minimums now and quite acceptable a few hours later after all.
Think Milan Linate, an airport plagued by early morning fog. A flight taking off from say Amsterdam to Milan may take off with the airport covered in dense fog that would make it impossible to land legally, and by the time it gets there it's a clear morning with no fog or clouds.
Of course as always you, the pilot, are responsible for your actions and if you take off knowing your destination is currently closed for you you'd better have a viable alternate plotted just in case the expected improvement in conditions doesn't happen.


Can drum lessons be applied to mallet percussion instruments?

Question: I recently got a glockenspiel for fun. I'm a beginner when it comes to percussion. I'm wondering if I can see it as a drum, and watch drum lessons or should I only look at lessons that are specific for mallet percussion.
Answer: The glock is much, much closer to a keyboard than it is to drums. The fact that it needs beaters or hammers (or mallets) to produce sound is as close as it gets. there are many different ways in which to hit drums, producing different sounds, which don't apply to glocks, or xylophones, or even vibes for that matter.
Instead, consider the mallets to be extensions of your arms/handsfingers, used in order to make the instrument sound. The only real relationship is that both drums and glocks need to be hit to produce sound. Plus, if it's a one or two octave glock, the movements in comparison to playing a drumkit are also quite foreign.
Comment: I found things like a roll (aka tremolo) on the glock is completely specific to it and doesnt exist on the piano. ie the muscles you develop from doing it. I'm sure there are other things too. but I found the roll to be the most important so far.
Answer: Learning drum rudiments would definitely apply to playing glockenspiel. There are many drum techniques that apply to mallet instruments as well, such as marching/field drum techniques.
That said, there are rock drum kit techniques that are not related, such as how to hit cymbals, hi-hat and kick techniques, and other elements.
Answer: You're not going to need drum rudiments - the rolls, paradiddles, flams etc. that drummers spend time on.  And you're not going to have to be the time-keeper of a band.
If you get yourself into a band, worry about technique when it's required by the music they give you.  Until then, just pick some tunes out.
Answer: Just think of it as a percussion instrument.  One that requires mallets you'll want to spend time on developing proper hand and mallet technique. Notes same like a drum but certainly not the rhythmic foundation of the ensemble.  Your timing and control would improve by learning and practicing some snare drum rudiments or exercises(not for musicality, but a great idea to add to your practice regime.
This is because when you learn the notes/scales etc. they must be played with good timing and clean, sometimes at fast tempos too. As a 20 year drummer and percussionist myself I'd recommend you try incorporating certain rudimental snare drum exercises into your practice routine.  Your overall technique and rhythmic timing would certainly benefit.


Staging Environment & Migration to TFS

Question: My team from Microsoft already has a SharePoint site up and running. My job is to take a portion of it and migrate it to TFS. My Manager told me that I have to find a staging environment for sharepoint so that I don't mess with the real site incase I mess up. However, on all of my searches I can't seem to figure how to set up a staging environment in Visual Studio for SharePoint and how to migrate info from SharePoint to TFS.
If my question is way too loaded, please let me know what is wrong with this question so it can be more specific.
Comment: what i understand...you have a on prem sharepoint site, and want some development on it. for that you want to move that site collection into TFS server and you want to know what is procedure?
Comment: Sorry, I should have specified that what I was asking is actually two separate jobs.
First, there is a portion of the sharepoint site that I will be migrating to TFS and I am not sure how to do this process.
Second, I am also updating the sharepoint site, but I want to first set up a staging environment so that when i'm testing the changes, it won't mess up the actual site. I am not clear on how to set up this staging process either.
Answer: Sorry, but this doesn't sound quite right. A staging environment should match the configuration of the prod environment. I wouldn't just tell someone to create a staging environment, I'd give them the script that configured prod so they could just run the script to duplicate the environment. Without the script, you'd at least need to know the service pack level of prod, in addition  to knowing what web apps exist, what settings they're configured with, etc. (to be clear, a staging environment isn't set up in visual studio, it's a full install of SP running on a different box (or, boxes)).
As far as taking a portion of the site and moving it to TFS? This doesn't make sense. TFS will store developer assets, such as custom web parts, apps, workflows, etc. But, you don't just take them from SP. They've been deployed to SP, so you would need a copy of the source code to move to TFS.
So, if you need a staging environment, you'd first need to know what prod is: SP 2013, SP 2010, Office 365? Then, unless its office 365, you get a spare server and spare SQL instance and install SP, configuring it as it exists in prod. Then, ramp up on building Solutions or Apps.
Good luck.
Comment: Definitely this. Staging should also be cloned as a copy of production for each full feature release. You never want production and staging to be out of date as staging is as much  about testing your deployment process as it is testing as close to production as possible.

Staging Environment & Migration to TFS


What's the difference between True vs Magnetic headings?

Question: What is the difference between a true and a magnetic heading?
Why are/were magnetic headings used in aviation?
Answer: The "heading" refers to the direction an aircraft is pointing. For a Magnetic Heading, this is in relation to Magnetic North. For a True Heading, this is in relation to True North.
True North is directly over the earth's axis.
Magnetic North is somewhere over Canada, moving towards Russia.

To get the Magnetic Heading, you just read it off the magnetic compass.
To get the True Heading, you need to first read the magnetic compass, then either add an Easterly, or subtract a Westerly, magnetic variation; based upon the isogonic lines on your sectional (the purple dashed lines labeled 5°W, 3°E, etc).
Example 1: Magnetic Heading 177 w/ 3 degrees East Magnetic deviation = true course 180.
Example 2: Magnetic Heading 177 w/ 3 degrees West Magnetic deviation = true course 174.

Because of this, in the past, magnetic headings were used because a simple compass could be used. Finding reliable true headings was difficult until the era of things like the gyrocompass (patented in 1906 (Germany) and 1908 (USA)) and more recently, GPS.
Comment: You also need to take into account the compass deviation table which (hopefully) compensates for built-in magnetic influences.
Comment: Note that gyrocompass only works when stationary or moving slowly, so while it existed in the early days of aviation, it couldn't be used on aircraft. Only with introduction of inertial navigation systems aircraft got gyroscopes good enough to align before departure and then maintain the true north with useful precision during the flight.
Comment: Also GPS alone can't tell you true heading, because it can only calculate position and from it true track, but that differs from heading by (unknown) wind. What it can be used for is improving precision of INS.
Comment: Here's a question and answer what happens when you follow a constant magnetic heading due to compass deviation:http://aviation.stackexchange.com/questions/13248/klax-hdg-090%c2%b0-cross-the-atlantic-where-are-we-now/13249#13249
Answer: True North is the North Pole. The maps used for navigating are oriented to the North Pole. A pilot can measure the direction between two points to create a 'track' or 'course' to fly in degrees true.
Magnetic North is where the compass points - which is not actually the North Pole. Magnetic North is currently over northern Canada.
The angular difference between True and Magnetic north is called Magnetic Variation. This number varies depending on where you are on the earth.
Magnetic Variation is the bugbear of many student pilots. Why is it important? Well if your track to fly (ascertained from a map) is 360 degrees true in relation to the North Pole, you should be flying right to the North Pole. But 360 degrees on the compass points to Magnetic North in Canada. If you haven't applied magnetic variation, you could be flying as much as 15 degrees or so off course.
Runway names are the headings given in degrees magnetic, but as magnetic north is slowly moving, occasionally the runway name (eg 35/17) will change.
Answer: The true north pole, aka the celestial north pole, is the point on the Earth's surface intersecting Earth's rotational axis on the northern hemisphere (and thus the axis around which all stars appear to rotate). Prior to the introduction of the Global Positioning System, there were no perfect indicators of true north.
Two competing and often conflicting definitions of north have been used prior to the advent of GPS (and since). Magnetic north is the direction in line with the Earth's magnetic field, thought to be caused by the convective flows of liquid iron in the Earth's outer core, which causes a compass to point toward the magnetic north pole. An approximation of "celestial north" is in the direction of Polaris, which is a fairly bright star in the night sky and also the closest such star to Earth's rotational axis (and thus "true north") for about the last 1500 years.
First, the two poles do not coincide; here's a Google Earth image showing true north in green and magnetic north in red:

As you can see, they're close, especially from the perspective of those of us in the New World, but if you were sailing off the west coast of the British Isles, you might see up to a ten-degree difference between your compass and Polaris, and that's significant over a distance of even a few hundred miles. Navigators have known of this difference, known as the "magnetic declination", for centuries, and it was a secondary driving reason for the solution to the "problem of longitude" (how to determine, quickly and accurately, your current longitude; knowing this, in addition to being a key coordinate of your position at sea, also allows you to determine the necessary amount of "declination" from magnetic north to determine true north and thus the correct magnetic heading to your intended destination).
Second, Earth's magnetic pole changes over time; here's a map showing the changes in the surveyed position of the magnetic north pole through Nunavut, Canada over the past 130 years or so:

As you can see, the magnetic pole appears to be approaching true north, possibly due to gyroscopic stabilizations of the convective flows within earth's liquid inner layers. Again, for most of the U.S. the practical effects of observed shifts are minimal, but it has much more pronounced effect near the Prime Meridian which happens to be nearly perpendicular to the line between true and magnetic north.
Comment: Actually, on the west coast of USA, the effect is much more pronounced than in UK. In London, magnetic variation is a little less than 1°W while in Seattle it is almost 16°E! Because the magnetic field is not very regular. See https://en.wikipedia.org/wiki/File:World_Magnetic_Declination_2015.pdf
Answer: True north (geodetic north) is the direction along the earth's surface towards the geographic North Pole.
True geodetic north usually differs from magnetic north (the direction a compass points toward the magnetic north pole), and from grid north (the direction northwards along the grid lines of a map projection).

Magnetic declination is the angle between compass north (the direction the north end of a compass needle points) and true north (the direction along the earth's surface towards the geographic North Pole).
So to get Magnetic Heading, look at your compass. To get the true heading, you will need to look to a WAC chart, and depending on your position, add or remove degrees according to your position's Magnetic declination .
Answer: Magnetic heading works with a compass. No need for electricity, no need for a radio, no need for satellites. If you have a failure of any navigation system, or main battery, your compass will tell you the magnetic pole (which is slightly different than the real pole, depending where you are in the globe). It's a safety feature. Satellite work great, when they work, and when your navigation system works. If your battery is dead or something get disconnected, you need some backup that works! You can't say "I lost my battery fuse for my navigation, therefore I got lost and we are going to die" you need a backup, that's why.
Answer: True heading is true course ( as plotted on the chart) corrected for the wind.  Period.  Plus or minus magnetic variation gives you a magnetic heading, then compensation for compass deviation gives you your compass heading.  Remember the old adage?...True Virgins Make Dull Company.  Works every time.


How to increase quantity of Ginger Beer Plant

Question: I'm looking to increase my quantity of GBP to share with a friend. I've brewed a few batches of ginger beer, but I always end up with the same amount or slightly less GBP than I started with. What needs to be done to come out with more GBP after a batch, or how can I just increase my quantity of GBP? Leave it in a jar full of sugar and ginger for n days?
Answer: This is an universal solution that works for most microorganisms, and I bet it will for yours, too. After all, both Saccharomyces and Lactobacillus finds everything they need in it, so symbiotic colony of them should as well.
Use beer wort, may be from extract. It's a soup of everything microorganisms needs. OG at about 8 to 10 Plato (1.030 to 1.040 as Americans call it).  Put it in a jar. Add yeast nutrient, compound one. Yeast cell walls kind, if possible. Aerate it by swirling. Try on small part of your GBP, and see yourself. Magnetic stirrer would be ideal, but if you don't have, swirl it three, four times a day, at least few minutes each. This is to remove CO2 and add oxygen.


Wallpaper removal: Should I use chemicals in addition to a steamer

Question: I'm removing wallpaper that has a layer of paint underneath. Currently, I'm using a scoring tool then a steamer to remove the different layers. As you can imagine this is a slow process. Would it be advantageous to use chemicals before I use the steamer?
Answer: I never had luck with chemicals... steamer & lots of elbow grease was the only thing that worked for us :-\
Comment: +1 agreed.  Seems like there should be an easier way, but I've tried lots of things and none of them seem to be any easier.
Answer: I have witnessed surprising results by covering wallpaper with a thick layer of wet joint compound, right out of the 5 gal bucket.  We call it "mud" in my region.  Let it sit a while, and the moisture and weight will almost remove the wallpaper by itself.  Try it yourself on a small area and see if it will work in your application.
Answer: Same as Luke in our case as well. We tried DIF, then Piranha, and while those did make a difference, nothing worked better in terms of getting the paper off in nice big sheets  than a Shark steamer and a little patience.
Answer: we removed an entire house worth of wallpaper when we bought this house. some of it was 1 layer (dining room), some of it was multiple layers (7 in the bedrooms, no, really, there were 7 layers!) and 1 layer in the kitchen that was over drywall (the rest were over plaster walls)
chemicals did no better than a streamer with a touch of hand soap in the water
plaster walls - wet the wallpaper with a water bottle - dont soak it that its running down the wall but get it moist - then use the steamer and a 4 inch putty knife and scrape it off
hold the steamer to the wall, about 20-30 seconds - it should begin to peal - scrape it off and move on. once you get the hang of it, you can scrape off 1 section while steaming another.
this is a very hot process - if you have air conditioning, use it.
drywall walls - you need to be much much more careful; the paper backing on the drywall can peal with the steamer also. hopefully, the drywall was primed before they put the wallpaper on - ours wasen't. same process, but be much more careful; opting to pull the paper up by hand when you can and only use the steamer when you need it.
if you do wet the drywall backing, you'll need to cut the bubble on the paper the steamer produces out with a utility knife. prime it, plaster in the gap the cutout made and prime and paint (or whatever your final coat is).
keep a dust pan and broom close by and cover the floors if you can / plan to salvage them. the wet glue left on the wallpaper you just let fall to the floor after scraping it off the wall will stick to hard wood floors and probably stain carpet.
good luck.
-Mario
Answer: After you've scored the wallpaper, spray it down with water.  Come back a bit later with the steamer.


What's special about Saturn that it has distinctive rings?

Question: This may overlap with other questions, but I'm asking what is unique about Saturn in location, properties, etc that is has far more pronounced rings?   It's between Jupiter and Uranus and Neptune in size and position.  So what's special?  Is there some Goldilocks zone of rings formation?   Or is it just an accident of history?
Comment: I'm not sure you can say it is "special". All 4 gas giants have rings.
Comment: I understand what you're saying, but that's totally pedantic.   Would you claim it's not a well-formed question to ask why Earth has a giant satellite and Mars only has two tiny ones?   Maybe the answer is that it's just an accident of history that a large body impacted the Earth and created the Moon, but rejecting the premise of the question is just silly.
Comment: @FlorinAndrei:   If this is right, can you cite evidence and make an answer?
Comment: @RobJeffries:  This is sort of like saying Earth and Mars both have natural satellites.   Yes, it is technically true, but really?
Comment: I'm with Rob on this - they all have rings to a greater or lesser degree. And yes, Earth and Mars have natural satellites.
Comment: It's an accident of history that Saturn has such large, dense, pronounced rings - far more visible than the rings that all giants normally have.
Answer: Saturn's rings are unique in that a lot of the rings compositions contain new and recycled material. Much of the uniqueness is complementary from Saturn's moons, which play a critical role in shaping and recycling the rings materials.
A great example is the moon Enceladus, which contributes largely to the E Ring. Icy material is ejected from Enceladus, a process called cryovolcanism (spewing plumes of icy materials instead of silicate rock); due to the lack of atmospheric pressure and low surface gravity, Enceladus doesn't hold the material that it ejects, but rather feeds material into the E Ring. Discovered by Cassini, the material is comprised of simple hydrocarbons such as methane, propane, acetylene and formaldehyde.
A contributing factor for the unique shaping of the rings and much of their orbital stability stems from the moons also. Another well known example is the Cassini Division and a process called orbital resonance. Essentially the moon Mimas orbits once for every two orbits for material inside the Cassini Division. As a result of that orbital resonance the material receives accumulation of radial momentum, the effect of such accumulation forces a tug of war with the particles. Mimas attracts the material pulling it into the A Ring as the material increases in velocity, resulting in the division.
Other moons have also been documented to have this effect, such as the moons Pan and Daphnis in the A Ring, however it is thought that the effect from these smaller moons only create a division around 10km in width. Stability can be exaggerated from the F Ring, with the moons Pandora and Prometheus. These moons twist the material into a spiraling vortex, like a horizontal tornado encircling the planet. Processes of stability arise from moon ringlets, such as the Titan Ringlet. Titan has orbital resonance with material in the C Ring and provides radial momentum with the Colombo Gap, the gap is slightly elliptical rather than circular (just as Titan is) and the material is attracted towards Titan in the same pattern, in a process called apsidal precession. This creates a compression and expansion of the rings giving them stability while accumulating velocity due to orbital resonance.
Distortions from the moons on an independent inclination to the rings as they come close to the rings, also pull material from the rings and spread it around in chaos, additionally recycling material.
Each ringlet has an individual story as to the forces which make that ringlet unique, comprising of the orbital parameters of the moons and the unique positioning of the forces around them. Along with material that is recycled in a unique fashion not evident with other planetary rings system.
The uniqueness stems from these factors.
Comment: This answer is interesting, but it's more about enumerating ways the rings are unique -- it doesn't answer the question of why they exist and are that way in the first place.    The question is "What's special about Saturn?"   not "What's special about the rings?"  If you reread the original question the distinction should be more clear, I hope.


Kindle Keyboard shortcut for returning to last "page"

Question: I have a Kindle Keyboard, and sometimes, while reading a book, if I press on the left/right key, it will throw me off to the previous/next chapter's first page.
(the nearby up/down keys invoke the dictionary, so this does happen...)
Does anyone know of any shortcut that can be used to go back to my original place? Even after the throw-off, there's a little cursor on the "progress bar" at the bottom that shows where I've previously been, so I suspect such shortcut exists.
Answer: The back button gives you back to your original place.


Fundamentals of electrostatics

Question: Suppose I have a Gold Leaf Electroscope and the leaves are observed to diverge by a certain amount. Now if I send a beam of X-rays and allow it to fall upon the electroscope for a very short period of time, what exactly will happen?
Answer: " By using a specially calibrated microscope to observe the movement of the strips, a scientist can measure the voltage of the charge in microvolts (millionths of a volt). When the electrical capacities of both the electroscope and the body producing the charge are known, electric currents moving through ionized air can be measured. Even when the capacities are not known, these currents can be detected. Therefore, the electroscope is used for detecting X rays, cosmic rays, and radiation from radioactive material. These rays ionize the air and pass through it as a kind of electric current. The current either charges or discharges an electroscope. "

Fundamentals of electrostatics


Why does a time series have to be stationary?

Question: Would like to understand primary reasons for making a data stationary?
I understand that a stationary time series is one whose mean and variance is constant over time. Can someone please explain why we have to make sure our data set is stationary before we can run different ARIMA or ARMA models on it?
Does this also apply to normal regression models where autocorrelation and/or time is not a factor?
Comment: You don't require stationarity to run an AR$I$MA model, since if the $I()$ order is $>0$, it's explicitly nonstationary.  Stationarity is an assumption of ARMA, however.
Comment: Stationarity requires more than constant mean and variance. Weak stationarity requires that covariance function $cov(X_t,X_{t+h})$ doe not depend on $t$.
Comment: What are ARM models? Did you mean ARMA?
Comment: +1 for the order comment, though strictly, that's only if $I$'s order is in $\{0, 1, 2, ...\}$. For arbitrary orders, there's [ARFIMA](http://en.wikipedia.org/wiki/Autoregressive_fractionally_integrated_moving_average)
Comment: @Glen_b  Can ARIMA models  be applied fr any non stationary series? Or there are some specific non stationairty cases  in which ARIMA cana be applied ?
Answer: Stationarity is a one type of dependence structure.
Suppose we have a data $X_1,...,X_n$. The most basic assumption is that $X_i$ are independent, i.e. we have a sample. The independence is a nice property, since using it we can derive a lot of useful results. The problem is that sometimes (or frequently, depending on the view) this property does not hold.
Now independence is a unique property, two random variables can be independent only in one way, but they can be dependent in various ways. So stationarity is one way of modeling the dependence structure. It turns out that a lot of nice results which holds for independent random variables (law of large numbers, central limit theorem to name a few) hold for stationary random variables (we should strictly say sequences). And of course it turns out that a lot of data can be considered stationary, so the concept of stationarity is very important in modeling non-independent data.
When we have determined that we have stationarity, naturally we want to model it. This is where ARMA(AutoRegressive Moving Average) models come in. It turns out that any stationary data can be approximated with
stationary ARMA model, thanks to Wold decomposition theorem. So that is why ARMA models are very popular and that is why we need to make sure that the series is stationary to use these models.
Now again the same story holds as with independence and dependence. Stationarity is defined uniquely, i.e. data is either stationary or not, so there is only one way for data to be stationary, but lots of ways for it to be non-stationary. Again it turns out that a lot of data becomes stationary after certain transformation. ARIMA(AutoRegressive Integrated Moving Average) model is one model for non-stationarity. It assumes that the data becomes stationary after differencing.
In the regression context the stationarity is important since the same results which apply for independent data holds if the data is stationary.
Comment: I would suggest you to put this part of your response ("This is where ARMA models come in. It turns out that any stationary data can be approximated with stationary ARMA model, thanks to Wold decomposition theorem. So that is why ARMA models are very popular and that is why we need to make sure that the series is stationary to use these models.") in bold because this is which primarily answers the question.
Comment: I think people are confused about stationarity requirements though. I think you can have time-series *instances* that are non-stationary but yet if you train across many instances you can still potentially learn the problem. It needs to go deeper than "time series stationary good non-stationary bad".

People also need to distinguish between features and learning target (class labels whatever).  We need *clear* statements on this.
Answer: What quantities are we typically interested in when we perform statistical analysis on a time series? We want to know

Its expected value,
Its variance, and
The correlation between values $s$ periods apart for a set of $s$ values.

How do we calculate these things? Using a mean across many time periods.
The mean across many time periods is only informative if the expected value is the same across those time periods. If these population parameters can vary, what are we really estimating by taking an average across time?
(Weak) stationarity requires that these population quantities must be the same across time, making the sample average a reasonable way to estimate them.
In addition to this, stationary processes avoid the problem of spurious regression.
Answer: To add a high-level answer to some of the other answers that are good but more detailed, stationarity is important because, in its absence, a model describing the data will vary in accuracy at different time points. As such, stationarity is required for sample statistics such as means, variances, and correlations to accurately describe the data at all time points of interest.
Looking at the time series plots below, you can (hopefully) see how the mean and variance of any given segment of time would do a good job representing the whole stationary time series but a relatively poor job representing the whole non-stationary time series. For instance, the mean of the non-stationary time series is much lower from $600<t<800$ and its variance is much higher in this range than in the range from $200<t<400$.
Comment: This is probably the most accurate and straightforward answer.
Answer: An underlying idea in statistical learning is that you can learn by repeating an experiment. For example, we can keep flipping a thumbtack to learn the probability that a thumbtack lands on its head.
In the time-series context, we observe a single run of a stochastic process rather than repeated runs of the stochastic process. We observe 1 long experiment rather than multiple, independent experiments.
We need stationarity and ergodicity so that observing a long run of a stochastic process is similar to observing many independent runs of a stochastic process.
Some (imprecise) definitions
Let $\Omega$ be a sample space. A stochastic process $\{Y_t\}$ is a function of both time $t \in \{1, 2, 3, \ldots\}$ and outcome $\omega \in \Omega$.

For any time $t$, $Y_t$ is a random variable (i.e. a function from $\Omega$ to some space such as the space of real numbers).
For any outcome $\omega$ the series $Y(\omega)$ is a time-series of real numbers: $\{Y_1(\omega), Y_2(\omega), Y_3(\omega), \ldots \}$

A fundamental issue in time series
In Statistics 101, we're taught about a series of independent and identically distributed variables $X_1$, $X_2$, $X_3$ etc... We observe multiple, identical experiments $i = 1, \ldots, n$ where an $\omega_i \in \Omega$ is randomly chosen and this allows us to learn about random variable $X$. By the Law of Large Numbers, we have $\frac{1}{n} \sum_{i=1}^n X_i$ converging almost surely to $\operatorname{E}[X]$.
A fundamental difference in the time-series setting is that we're observing multiple observations over time $t$ rather than multiple draws from $\Omega$.
In the general case, the sample mean of a stochastic process $\frac{1}{T} \sum_{t=1}^T Y_t$ may not converge to anything at all!
For multiple observations over time to accomplish a similar task as multiple draws from the sample space, we need stationarity and ergodicity.
If an unconditional mean $\operatorname{E}[Y]$ exists and the conditions for the ergodic theorem are satisfied, the time-series, sample mean $\frac{1}{T}\sum_{t =1}^T Y_t$ will converge to the unconditional mean $\operatorname{E}[Y]$.
Example 1: failure of stationarity
Let $\{Y_t\}$ be the degenerate process $Y_t = t$. We can see that $\{Y_t\}$ is not a stationary (the joint distribution is not time-invariant).
Let $S_t = \frac{1}{t} \sum_{i=1}^t Y_i$ be the time-series sample mean, and it's obvious that $S_t$ doesn't converge to anything as $t \rightarrow \infty$: $S_1 = 1, S_2 = \frac{3}{2}, S_3 = 2, \ldots, S_t = \frac{t+1}{2}$. A time invariant mean of $Y_t$ doesn't exist: $S_t$ is unbounded as $t \rightarrow \infty$.
Example: failure of ergodicity
Let $X$ be the result of a single coin flip. Let $Y_t = X$ for all $t$, that is, either $\{Y_t\} = (0, 0, 0, 0, 0, 0, 0, \ldots)$ or $\{Y_t\} = (1, 1, 1, 1, 1, 1, 1, \ldots$.
Even though $\operatorname{E}[Y_t] = \frac{1}{2}$, the time-series sample mean $S_t = \frac{1}{t} \sum_{i = 1}^t Y_i$ won't give you the mean of $Y_t$.
Answer: First of all, ARIMA(p,1,q) processes are not stationary. These are so called integrated series, e.g. $x_t=x_{t-1}+e_t$ is ARIMA(0,1,0) or I(1) process, also random walk or unit root. So, no, you don't need them all stationary.
However, we often do look for stationarity. Why?
Consider the forecasting problem. How do you forecast? If everything's different tomorrow then it's impossible to forecast, because everything's going to be different. So the key to forecasting is to find something that will be the same tomorrow, and extend that to tomorrow. That something can be anything. I'll give you a couple of examples.
In the I(1) model above, we often assume (or hope) that the error distribution is the same today and tomorrow: $e_t\sim\mathcal{N}(0,\sigma^2)$. So, in this case we are saying that tomorrow the distribution will still be normal, and that its mean and the variance will still be the same 0 and $\sigma^2$. This did not make the series stationary yet, but we found the invariant part in the process. Next, if you look at the first difference: $\Delta x_t\equiv x_t-x_{t-1}=e_t$ - this cat is stationary. However, understand that the goal was not really to find the stationary series $\Delta x_t$, but to find something invariant, which was the distribution of errors. It just happens so that in the stationary series by definition there will be invariant parts such as unconditional mean and variance.
Another example, say the true series are: $x_t=\alpha t+e_t$. Say, all we know about the errors is that their mean is zero: $E[e_t]=0$. Now, we can forecast again! All we need is to estimate the growth rate $\alpha$, that's what was invariant and the mean of errors. Every time you find something invariant, you can forecast.
For forecasting we absolutely need to find the constant (time invariant) component in the series, otherwise it's impossible to forecast by definition. Stationarity is just a particular case of the invariance.
Answer: Since ARIMA is regressing on itself for the most part, it uses a type of self-induced multiple regression that would be unnecessarily influenced by either a strong trend or seasonality.  This multiple regression technique is based on previous time series values, especially those within the latest periods, and allows us to extract a very interesting "inter-relationship" between multiple past values that work to explain a future value.
Answer: Time Series is about analysing the way values of a series are dependent on previous values. As SRKX suggested one can difference or de-trend or de-mean a non-stationary  series  but not unnecessarily!) to create a stationary series. ARMA analysis requires stationarity. $X$ is strictly stationary if the distribution of $(X_{t+1},\ldots,X_{t+k})$ is identical to that of $(X_1,\ldots,X_k)$ for each $t$ and $k$. From Wiki: a stationary process (or strict(ly) stationary process or strong(ly) stationary process) is a stochastic process whose joint probability distribution does not change when shifted in time or space. Consequently, parameters such as the mean and variance, if they exist, also do not change over time or position. In addition as Cardinal has correctly pointed out below the autocorrelation function must be invariant over time (which means that the covariance function is constant over time) converts to parameters of the ARMA model being invariant/constant for all time intervals.
The idea of stationarity of the ARMA model is closely tied into the idea of invertibility.
Consider a model of the form $y(t)=1.1 \,y(t-1)$. This model is explosive as the polynomial $(1-1.1 B)$ has roots inside the unit circle and thus violates a requirement. A model that has roots inside the unit circle means that "older data" is more important than "newer data" which of course doesn't make sense.
Comment: A bit of a quibble: It is not quite clear what you mean when you say that "$X$ is second-order stationary if the first two moments are invariant over time." Normally, when I think of second-order stationarity, I think of the autocorrelation function being invariant over time in addition to the invariance of the mean. This is, of course, a (*much*) stronger condition than the (naive?) interpretation of the one you state.
Comment: The mention of second-order stationary seems to have been lost in your most recent edit. Was that intentional? (My original comment was more directed toward second-order stationarity than strict stationarity.)
Comment: :cardinal I guess I felt that your comment was important and made it clearer as to what was being assumed. If you think the idea of "second order stationary" adds clarity please help me add it to my answer in a way that sheds light in simple straightforward English.
Answer: In my view stochastic process is the process which is govern by three statistical properties which must be time -invariant .They are mean variance and auto correlation function.Though the first two doesn't tell anything about the evolution of the process in time ,so the third property which is auto-correlation function should be considered which tell one that how the dependence decay as the time proceed (lag).
Comment: This confuses being a stochastic process and being stationary, so it starts with a fundamental error. What does your answer add to those already posted?
Answer: To solve anything we need to model the equations mathematically using statics.

To solve such equations it needs to be independent and stationary(not moving)
In stationary data only we can able to get insights and do mathematical operations(mean, variance etc..) for multi-purpose
In non-stationary, it is hard to get data

During the conversion process, we will get a trend and seasonality
Comment: None of your answers make sense. The premise of the question is wrong. Many time series can be deemed to be non stationary both theoretically and observationally. There are many methods to deal with this too for example !. differencing or seasonal differencing the series or 2. including cyclical components such as sine waves.
Comment: @MichaelChernick During differencing and seasonal differencing we are converting non-stationary series to a stationary one. I accept your point that many time series are non-stationary but to solve it mathematically we need to convert it to stationary one right


Why isn't there a Cyanogenmod stable ROM for my device?

Question: Why don't the developers develop a stable ROM for my device? They have stable ROMs for similarly-named devices from the same manufacturer, even ones that came out after my phone. If the devices are similar, and there's already a stable ROM for one, why is it so hard to make a stable ROM for mine too?
Comment: Not regarding to the question, but try Focal, will solve you  camera problem.
Answer: Two devices with similar names, like the Sony Xperia Z and the Sony Xperia Z1, don't necessarily have the same kind of hardware. Sometimes there are even devices sold under one model name, such as the Samsung Galaxy SII, where the variants available in different countries have completely different systems-on-ship (SoCs) and other different hardware.
Devices with different hardware need different drivers &c. and a lot of system integration work that can't be shared between the two. Testing an unstable release to find the problems with it is very time-intensive, and of course can only be done on the exact hardware being targeted.
Since Cyanogenmod is made by enthusiast developers, rather than by people who are paid to do it, support depends on having an interested community of people with the system integration knowledge needed, and enough such people having that particular phone to run and test the ROM images.
It may be that there's not much more work required to support your device, but the people who might be able to do that don't happen to have one. Or it may be that none of the porters who have your device have enough free time right now to dedicate to testing and fixing ROMs. Lots of volunteer projects like this are stopped when members have children or start new jobs.
Even if you don't have the necessary knowledge, there are other ways you can help get your device supported. You might be able to help by contributing some money to support the developers, devices so that more enthusiasts can spend time working on it, or by testing and reporting bugs to make the process faster. If you ask the Cyanogenmod community how you can get involved and what would help, I'm sure they'd respond positively to that.


Are the irritating web site warnings about cookies an intentional consequence of European legislation?

Question: It seems that in the last couple of years, it has become standard for web sites to have irritating pop-over notifications that their web site uses cookies "to enhance your user experience" or something like that. As far as I can tell, this is done in compliance with the European Union's GDPR regulations (though that is perhaps not entirely true). I find the notifications to be totally uninformative and irritating, so I am curious whether this practice was an intended consequence of those laws or regulations, or whether it was an unintended consequence of a regulation that was intended to compel a different sort of behavior.
Answer: Yes, it was intended. It is because the law requires the sites to allow you to decide if you want cookies that are not necessary and allows you to opt in and out of specific cookies.
There just isn't a good way to do those things without making you click stuff.
Comment: This, I believe, became a requirement before GDPR. There have been statements from EU officials that the intended effect has not been achieved and that it is, indeed, very irritating.
Answer: Yes, it is intended.
Good would be to have a button together with the message to turn of cookies. This is rare, but for example slashdot.org does this.
Some reasonably good sites let you turn off all cookies with three clicks; it looks very much like they all use the same software for this.
Other sides make it ridiculously difficulat. arstechnica.com used to have links to 50 pages of their advertisers where you could supposedly turn off cookies for each advertiser individually. That's the kind of thing that makes you absolutely hate a website.
And then there is webmd.com . A website providing medical information. A website where I would expect more privacy than from other sites. The contrary happens: They don't allow access to their site unless you agree to their terms. According to the GDPR, such forced consent is not consent. In other words, webmd.com stores information about users residing in the EU without their consent, in absolute violation of GDPR.
Comment: A *reasonable* response would be for the web standards groups to come up with a standard for cookie management and push the notification and acceptance away from the website UI and into a standard implementation in the browser - the website can publish webhook endpoints for user changes and its all controlled in the http request headers and in a standard UI.  But no, instead we get a billion different implementations.
Comment: @Moo, that might be hard to square with the requirement that consent be active, i.e. opt-in, and that silence must not be taken as consent.
Comment: @DavidSiegel not at all, the browser simply drops any and all cookie headers until a corresponding consent for that cookie has been lodged or the cookie header is marked as "exempt" by the issuing party (which could trigger legal issues) and the browser can display an icon somewhere which shows that the website is claiming exempt cookies - this is all 100% controllable via a standardised technical implementation, but instead we get a mishmash approach because the solution is *legal appeasement* rather than technical in basis.
Answer: Here's a cybersecurity perspective. Cookies can have the ability to do a wide range of things. In addition to small arbitrary data, cookies can be used for authentication mechanisms and trackers. This from Wikipedia on tracker cookies:

...tracking cookies, and especially third-party tracking cookies, are commonly used as ways to compile long-term records of individuals' browsing histories – a potential privacy concern that prompted European and U.S. lawmakers to take action in 2011. European law requires that all websites targeting European Union member states gain "informed consent" from users before storing non-essential cookies on their device.

Security things to consider:

Line of death and zones of trust. Malware droppers can masquerade as cookie prompts. If you don't know what legitimate, trusted prompts should look like and WHERE they should be, it's pretty easy to get owned.
Review/change your browsers default cookie action, and clear cookies often.
Detect and block trackers with Privacy Badger. You may not have a good web experience blocking all cookies by default. This extension tries to determine the behavior of a tracker, and blocks it.
bonus: get a good ad blocker. Ublock Orgin is free and awesome.
bonus: make sure your connections are using SSL encryption with HTTPS Everywhere Most legitimate sites use SSL for their core content. Even so, lots of little 3rd party HTTP requests are made for tracking and adds... block them and watch lots of ads disappear, and it will also help warn you before going to bankofarnerica (...ARNERICA, yes, I've seen this phishing attempt from typo-squatted http sites).

Follow these tips for safer, faster browsing.
Comment: I appreciate the detail about the potential abuses of cookies, but it doesn't follow that the most effective way to address the issue is with vapid pop-over notifications. That just trains users to dismiss alerts without paying attention to them.
Comment: Agreed. However, because this mechanism drops files on the subject's machine, some legal systems require consent. In some countries, browser settings that permit cookies are all that are needed, some may leverage the pop ups, and others may require a notification within the webpage. Your question seemed to be partly fueled by annoyance with the mechanism, so I offered some work arounds.


How can we help good unanswered questions, which I myself do not know the answer to, get answered?

Question: Odds are good some questions will come up which no one currently on the site has a (good) answers for. What is the protocol for handling such questions?
Answer: You could post a link to the question on your blog, Facebook page or Twitter (for example).
If you use the URL from the "link" link then this includes your user id and visits using that URL are tracked. If you get enough visits within a given time period you might get the "Announcer", "Booster" or even "Publicist" badge.
Answer: From what I read in the FAQ, if a question is edited, that can bump it back up to the top of the list.  So if some time has gone by and you have edit privileges, you could clean up the question a bit.
This actually has the added benefit of not just bumping it to the top, but also it helps make sure the question is clear, readable, and easy to understand.  All of these things will help increase the likelihood that more people will be interested in spending time trying to answer it.
Answer: I am not sure I understand your question -- if you see a question that isn't answered, and you have the expertise or knowledge to answer it ... why wouldn't you?
The only time I would refrain from answering a question is when I know it is clearly off-topic, e.g.
https://softwareengineering.stackexchange.com/faq
Comment: I'm thinking about questions which I don't know the answer to, and clearly, no one so far on the site knows the answer to, but seem to be legitimate and on-topic. Though, I suspect I know the answer to this one - wait a few months, and throw a bounty on it.
Comment: @blue ah so your question is "How can we help good unanswered questions, which I myself do not know the answer to, get answered?" That was not at all clear from your Q


Derivative at the origin

Question: For which $a\in {\bf R}$ is $|x|^a$ differentiable at $x=0$ and what is the derivative there?
Comment: What do you have so far?
Answer: Hint: Let $a\gt 1$. Calculate $\displaystyle\lim_{x\to 0} \frac{|x|^a-0}{x-0}$. It is useful to work separately with the limit from the right and the limit from the left.
If $x\gt 0$, then $\dfrac{|x|^a-0}{x-0}=\dfrac{x^a}{x}=x^{a-1}$.
If $x\lt 0$, then $\dfrac{|x|^a-0}{x-0}=\dfrac{|x|^a}{-|x|}=-|x|^{a-1}$.
Now we need to show that the limit does not exist when $a\le 1$. For $a=1$, we are working with the familiar absolute value function, and the limit of the differential quotient from the right is $1$, while the limit from the left is $-1$.
If $a\lt 1$, the differential quotient blows up as $x$ approaches $0$ from the right.
Answer: Hint: take the definition of differential and separate it to left and right limits.
Answer: By definition, $f$ is called differentiable at the point $x_0$, if its increment $Δf=f(x_0+h)−f(x_0)$ may be represented as $$f(x_0+h)−f(x_0)=f'(x_0)h+α(x_0,h),$$
where $\alpha$ satisfies
$|\alpha(x_0,h)|=o(|h|),\quad h\rightarrow 0$. Thus is sufficient to write increment for $f(x)=|x|^\alpha$ at point $x_0=0$ for $h>0$ and  $h<0$

Derivative at the origin


What is the aerodynamic motivation behind vortex generators?

Question:
An airplane's wing creates lift efficiently when the airflow is parallel to the chord of the wing. Vortex generators twist the airstream on the wing surface.
Doesn't this kind of twisted airflow cause lift inefficiency?
Answer: You are correct that vortex generators create drag, so a successful installation depends on reducing some other drag even more. Airflow separation causes significant drag that vortex generators can reduce. The energy consumed by vortex generators making drag is injected into the boundary layer, delaying airflow separation and the eventual stall, which might be of even more value. Correcting poor flight characteristics on an existing design is often where they are used. The illustration of a wing stalling is easy to understand but may not be the best use of VGs since few wings fly continuously on the brink of separation.
Answer: No.  The vortex helps keep the boundary layer attached so lift is created for a longer time as the plane slows and the wing is tilting up & back for landing.

Image source
Answer: They only twist the flow in a little region just above the wing surface, whereas a substantial part of the overall lift is actually being produced by a huge package of air well above the wing being induced to move downward.  You could say they have a kind of catalytic beneficial effect much larger than their cost.
Yes there is energy consumed in making the vortex but that is usually offset by the drag reduction of the overall flow improvement achieved (they may be spinning, but the spinning air is a lot more orderly than random turbulence).  Usually VGs are used in local areas to help re-attach detached flow, but the best example of this is the popularity of VGs used as a "poor man's slat" along wing leading edges.
When aircraft have VG kits installed on the leading edges, it raises the stalling AOA somewhat less than half of what you get with a slat or slot, not bad for a row of little metal tabs.  From about 14-16 degrees for most airfoils to maybe 19-21 degrees (ballpark numbers for illustration).  On many light aircraft this is good for about 4-6 mph reduction in indicated stall speed.  On light twins VGs can also lower the minimum control speed to close to or even below the stall, a huge safety feature.  They also tend to drastically improve stall behaviour.
You would think leading edge VGs would come with quite a cruise speed penalty, but usually the penalty is negligible if at all, because there is a small drag reduction from the reduction of flow separated turbulence at cruise that offsets the energy used to create the vortices.  In a worst case, maybe a light twin with VGs will see a 3 mph hit on cruise speed, but the safety benefits are too massive for this to matter.
Answer: I am going to complement previous answers about VGs. All previous three answers are showing a fact:

Given a designed wing the stall angle can be reduced and also the maximum lift can be increased.

The actual motivation to use VGs is the overall most efficient solution. Your reasoning is right, a VG is introducing drag and, for a given angle of attack a less aerodynamically efficient wing.
However, let's take the problem from a different perspective. I have an airplane that I am desiging and I have several design parameters, imagine that one of the constrains of design is that, for example, we need to be able to be able to lift the aircraft with a given weight, but that point is not the nominal point, is just one design point in the envelop you shall design for.
Essentially, at design level, you will see what is the maximum ever lift you can generate and multiply by the surface and the dynamic pressure. Dynamic pressure will be given by the design point, and your designing parameters will be surface of the wing and maximum lift.
So... you are interested in optimizing the cruise condition... obviously you will try to make that wing, for the given lift of the cruise condition, having the less drag possible.
This is bringing you to a trade off, what will providing less drag, an extra surface or a set of VGs? Given this trade-off, you've got the installation or not of VGs.
Essentially you will be using the energizing capabilities of VGs when there is a trade off in an specific condition. I have described you a condition that is sizing the size of a wing (typical from tail plane) but you can also take a look to this question where another specific condition is discussed related to the engine nacelle.
Comment: Keep in mind that the OP has been asking lots of questions re: building his own ultralight.


Why did the Apollo Lunar Module have four landing legs?

Question: Why did the Apollo Lunar Module have four landing legs? Is not just three legs enough? Also, three legs guaranties they always form a plane, four does not, as the fourth leg may dangle. To have the centre of mass over the landing leg polygon, even if one of the legs broke, you would need at least five. So why four?
Comment: Related: [Why are four-legged chairs so common?](http://physics.stackexchange.com/q/230685/14091) on [physics.se].
Comment: This is briefly touched on in [the *From the Earth to the Moon* miniseries, episode 5 "Spider"](https://en.wikipedia.org/wiki/From_the_Earth_to_the_Moon_%28miniseries%29#Episodes), with a group of engineers discussing the number of legs. Whether or not it was a consideration at the time I don't know, but one issue that is specifically mentioned there is interference with thruster quads (four thruster quads and five legs means you risk interference; with four thruster quads and four legs, avoiding interference between them is trivial).
Comment: 1/6th gravity allows for choices you wouldn't make on Earth.
Comment: Gravity does not affect the structural configuration, only the actual expected loading distribution!
Answer: Three legs offers less safety margin for steep slopes and sideways landings.
If a three-legged lander touches down on a steep slope such that the center of gravity of the ship is outside the triangle formed by the contact points, it will tip over.
The four-legged lander has a substantially larger area inside the quadrangle formed by the contact points; as long as the CG stays above that area, the ship is stable.
Projected to the ground, the shortest horizontal distance the CG could tip and become unsupported:

for the three legged lander is half the landing gear radius;
for the four-legged, it's $ \frac { \sqrt 2 }{ 2 } = 0.7071 $ of the radius.

At the time of landing, with the tanks in the descent stage empty, and the ascent stage full, the LM's CG is fairly high, and the absolute stability limit is about 43º. A three-legged lander with the same gear-radius-to-CG-altitude ratio could tip over at 29º.
Obviously the LM was never intended to land on that steep a slope (I think 15º was the design limit, which A15 got close to). The larger concern was stability in cases where the lander touched down with a substantial horizontal velocity component. In such cases, the fourth leg buys a lot of stability margin.
Answer: There is some interesting information here.
Three legs were probably not robust enough, they do not appear to have been considered seriously for any length of time.
Five fixed legs was the main option considered at first, however this wasn't thought to have a wide enough footprint for reliable landings. Eventually they selected the final design of four widely-splayed legs, which were stored folded.
Though the four leg design does not seem suited to an uneven surface (not all in the same plane), part of each leg was collapsible to absorb shock.  In fact Apollo 15 did land at a moderate angle:

The vehicle at-rest attitude, as determined from the gimbal angles, was 6.9 degrees pitch up and 8.6 degrees roll to the left, resulting in a vehicle tilt angle on the lunar surface of approximately 11 degrees from the horizontal
  (Source)
Comment: There is a full LM at the Cradle of Avaition Museum in Long Island. Was supposed to be used on Apollo 19.  Pretty cool to see in person.
Answer: There's some interesting discussion of the Lunar Module design in chapter 6 of Chariots For Apollo (Brooks, Grimwood & Swenson 1979, NASA SP-4205).  In particular, chapter 6.4 notes that a five-legged design was initially considered, but was changed to a four-legged one both to save weight and to simplify the design, which was already based on a four-way symmetric frame:

Grumman had first considered five legs but, during 1963, decided on four. The change was dictated by the weight-versus-strength tradeoff that had produced the cruciform descent stage, with its four obvious attachment points. The revised gear pattern also greatly simplified the structural mounting of the vehicle within the adapter. Four legs set on the orthogonal axes of the lander (forward, aft, left, and right) mated ideally with the pattern of four reaction control "quads" (the basic four-engine package). The quads were rotated 45 degrees so the downward-thrusting attitude control engine fired between the two nearest gear legs, overcoming a severe thermal problem of the five-leg arrangement.

and also:

A retractable gear therefore replaced the simpler fixed-leg gear. Retractability also figured in the shift from five to four legs - the fewer to fold, the better.

Obviously, three legs would've been even lighter and easier to fold than four, but would've had the same issues with mounting and thruster quad placement as five legs: the LM design was based on a cross-shaped frame, with four simple and sturdy attachment points, and it had four symmetrically placed packs of attitude control thrusters whose exhaust had to be directed away from the legs.  Also, a three-legged design would've had a significantly smaller stability margin when landing on a slope, and/or if any residual horizontal velocity remained while landing.
Comment: The reduction from 5 legs to 4, for those reasons, is confirmed in the relevant chapter in the cheekily named [Haynes Manual](https://haynes.com/en-gb/nasa-saturn-v-owners-workshop-manual).
Answer: Note that this is consistent with our everyday experience. People talk about how a three-legged stool never wobbles, but by far most stools have four legs, for essentially the reasons given by the other answers.
Comment: But wheeled office chairs almost always have 5 wheels due to increased stability over 4 wheels. In my jurisdiction, 4 wheel office chairs are actually forbidden by workplace insurance safety rules. There is one 4-wheel stool (grandfathered in) which is noticably less stable.
Comment: Again consistent with the fact that our experience with chairs reflects the design issues facing the LM designers, as other answers indicate 5 legs were considered for their greater stability but rejected for other reasons.


Can you patent a card game?

Question: I have created a card game, the idea is somewhere between poker and slots. I hope to create a website to monetise the game but do not know whether I am able to patent the game in order to stop big companies from stealing the game. How effective is a patent at protecting a card game? Also, if so, then must I patent all small variants of the game also? It should be noted that I am from Australia where gambling websites are legal. Thanks.
Comment: You might try these questions at http://patents.stackexchange.com/ -- especially the practical ones.
Comment: @Tom, What do you mean by the phrase "gambling websites are legal" and to what *extent* are they legal?
Comment: While US related (and board rather than card game), you may wish to read of [7,264,242](http://www.google.com/patents/US7264242) which [has been going around in court for the past few years](http://www.law360.com/articles/649421/fed-circ-slashes-innovention-s-4-7m-game-patent-award) over the size of the damages owed (if it was willful infringement or not - that it infringed isn't in doubt). The judgment is against MGA Entertainment which is a Very Large Company. So yes, it can protect against big companies stealing the game.
Answer: Yes.
The AusPat database is an excellent source for looking for Australian patents. I did a quick search for "card game" and came across 276 results fitting those keywords. Not all involve the classic generic-52-card-deck format, but some do.
A good example - and one that seems similar to your idea - is "Modified blackjack game using non-standard blackjack card values", by Davinder Signh Sandhu. There's no direct link to it from AusPat.1
So yes, you can patent a card game in Australia.
At the moment, I don't have enough information to answer your other two questions.

1 I found a similar American patent with more information, though I have no proof that the two are in similar formats.
Comment: He mentioned to put the game online... surely your answer should tackle international concerns (because a competitor would be located overseas) instead of limiting yourself to "Australian patents"?
Answer: While many card games are patented in the U.S., it has been almost impossible to patent a card game or a board game in the last few years. The movement against software patents has resulted in a very broad application "abstractness" being used as a rejection, even though the courts have not defined it.

Can you patent a card game?


Encoding for arabic website

Question: i just want to know the difference between utf-8 and windows-1256 encoding.I am building arabic website which encoding is better to use.
Answer: utf-8 includes a wide range of characters (not only Arabic characters), while windows-1256 is an Arabic code page. I prefer utf-8 as not all computers install windows-1256 by default.
Answer: You could have Googled it. In short. Windows-1256 is a code page (meaning in this case only 8 bit characters are in there), UTF-8 encodes (almost) all characters out there.
Use UTF-8 if you have the choice.
Answer: UTF-8 can represent all supported character sets at once, while Windows-1256 can only support arabic + some latin characters needed mostly for french.
I'd go for UTF-8, just in case you want to use any non arabic characters in your site later.

Encoding for arabic website


What are the evolutionary factors that could create a species that looks like E.T.?

Question: Watching E.T. I was wondering what evolutionary factors could cause a species to have the appearance of E.T., like the environment he would likely live in and the gravity of his homeworld.
Comment: @AndreiROM, not so.  As someone who has studied university-level zoology, this is no more broad than being handed the skull of some deceased animal and being asked to describe its diet and other habits, an exercise that we were trained and expected to perform.
Comment: Hi, Stephanie, This question is really broad, and kinda constitutes idea generation. If you were to ask our opinion on some of your own ideas, for example, that would be fine. However for us to completely define the universe for you is out of scope for WB SE. Here's a good link to study all about what WB is about: http://meta.worldbuilding.stackexchange.com/questions/3263/scope-clarification-discussions?lq=1 (and may I also say that the image is really distracting, and far, far too large?)
Comment: I'm voting to close this question as off-topic because it constitutes idea generation.
Comment: @AndreiROM, this isn't broad at all, and isn't really idea generation either - no more than any other question anyway.
Comment: @MontyWild - we are being asked to define every parameter which might lead to this being's evolution. That is the definition of "too broad"
Comment: @AndreiROM As a trained scientist I support MontyWild's comments as correct. The question is neither too broad nor idea generation. As demonstrated by Monty's answer. I can understand in the abstract the question might seem too broad or idea generation, but appearances can be deceptive.
Answer: Assuming that E.T. is an evolved being and not a poorly bioengineered survey drone or just the cutesy anthropomorphic invention of Hollywood filmmakers that it actually is...
Environment
Given E.T.'s feet and legs, it is apparent that this is a ground-dwelling non-cursorial being.  Given that in the movie, E.T. does not display any superhuman strength or subhuman weakness, we can assume that its home world has gravity similar to our own.  The fact that E.T. and its technologically advanced crewmates appear to be voluntarily exposing themselves to our atmosphere indicates that there are atmospheric similarities between Earth and E.T.'s world, most probably having a similar pressure and composition.  There are most likely differences in the partial pressures of the various gases, but falling within the acceptable range for at least limited unprotected exposure for E.T.'s species.  There exists the possibility that given that this species appears to go about naked, that it has some sort of internal technological breathing apparatus.
Given E.T.'s short legs (especially when compared to the very long arms), we can assume that this is not an arborial species (since the toes are not long enough to be opposable given the size of the foot pad), and that it has no predators that need to be outrun, nor prey that needs to be pursued.  Since its fingers are of unequal lengths, it is unlikely that it does much in the way of brachiation, again making it non-arborial.
Diet
Given that it has binocular vision, this, combined with its small mouth and long arms, indicates that it most likely eats small items of soft food that occur mixed with non-food items, for which visual discrimination is important, and can be readily picked by hand.  This food may be sessile, or if motile, must be fairly small, like insects, capable of rapid acceleration but not high speeds over any long distance, hence the long arms that could grab a fleeing bug of some sort without requiring the whole creature to move much.  Given the short legs, this food is likely available within reach, not significantly above head level (which is variable, given the extensible spinal-column analogue).
The small mouth is suggestive that its food is not other large animals or plants that require significant effort to break up to an ingestible size.  Given that we don't see dentition implies that this species has no enemies which might be deterred by a display of dentition.  Otherwise, we cannot draw any conclusions about its dentition other than that no great number of teeth seem required to process its food, ruling out tough or fibrous foods that might require a lot of mastication to fit down the narrow neck.
The luminescence displayed by these beings in their upper torsos and in their longest digit may be evolved, but in an advanced social and technological species (assuming that they built their own starships) which has demonstrated a facility with vocal communication, is more likely to be a side-effect of some technological devices that facilitate communication and environmental manipulation.  Since it is unlikely that telekinesis could evolve where there are more efficient biological alternatives, the in-movie demonstration of telekinesis is most likely the result of some unobvious technological enhancement.
Evolution
While we can tell from this creature's body-plan that it has no enemies to outrun nor prey to pursue now, this does not exclude this from its species past.  That its legs appear unaccountably elephantine, in contrast to its slender arms and neck, suggests that its species may in the past have had longer legs, and that they have evolved to be shorter, and that the folds of skin may have occurred as a result of a mismatch in the rate of evolution between bone length and skin tautness.
That a species may have evolved to have shorter legs is suggestive that in its evolutionary past it did have a need for greater speed, but the species has long outlived such a need.  The greatest probability is that this species has both eliminated potential predators from its environment, and has been producing constructed dwellings for a long period of time, leading to both a lack of advantage in long legs, and an advantage in short legs.  This suggests a civilisation that may have lasted tens to hundreds of thousands of generations.
The evolution of the extensible neck indicates that this species has not been particularly speedy for a very long portion of its evolutionary history, yet had a need to look at things on different levels fairly closely.  This suggests a somewhat sloth-like metabolism, potentially as a response to low-nutritional-value food, which would tend to select for energy-saving traits.
Society
In the movies it is demonstrated that these are social beings, and it is generally accepted that sociability is a prerequisite for a technological society, such as one capable of building a starship.  Given that one individual (who we should not presume is in any way greatly out of the ordinary for its species) is capable of audible communication, including with another species, it should be assumed that its primary form of communication was evolved to be audible, and that any 'telepathic' communication is a later technological add-on that has since superseded the audible communication channel.
Also, given that these beings are slow and presumably patient and methodical and that given their physiology their society appears to have existed for a very long time, it can be reasoned that they have dealt with the issues of high energy consumption and the environmental degradation that a high-tech society tends to produce.  This may of course have led to a global-city-world, with no non-domesticated species remaining outside preserves, if any still exist, hence their apparent interest in the natural environment of a presumably less-degraded world at the borders of a populated area.
Comment: In the movie, E.T tries to eat a toy car. I'm pretty sure to remember the crunching noises. Don't you think E.T should have had teeth to produce such noises?
Comment: @Wyglaf, From what I remember, E.T. also failed to ingest the toy car, so its dentition - which I have already stated that it most likely has - is not up to processing die-cast metal.  This fits with the statement I have already made - that its jaws and dentition are not exceptionally strong and no great amount of mastication is required to process its food.
Comment: Oh, yes you're right. I now realize I didn't read your answer correctly. My bad...
Answer: As awkward and clumsy as they might appear to be planetside, ET's body structure seems very well-adapted to a spacefaring species.  I would therefore like to suggest that his species (or sub-species) may have begun more humanoid, but has spent long enough travelling between planets that their body structure has become adapted to spending long periods in space, either through natural evolution (due to crossbreeding of individuals who tended to spend long periods on space stations) or artificial breeding programs.
Watch some videos of astronauts navigating our own space stations in zero-g.  They mainly use their arms to grasp projections from the walls in order to maneuver, with their legs getting less use.  Since spacecraft weight is expensive, hallways tend to be cramped and narrow; it is therefore beneficial for an astronaut species to have as compact a shape as possible.  A humanoid optimized for life on such spacecraft may therefore have short legs and long arms/fingers (which may also be useful for operating control panels).  Large eyes are useful for seeing in low-light conditions, which could help save precious energy on lighting.  The extendable neck is a fairly complex adaptation and might have already been a feature of the species, although it would also find use in viewing multiple control displays while expending less energy; furthermore, the main problem with a long neck (strain on the heart) is less of an issue in zero-g.
ET's "telekinesis" is probably artificial and may be an implanted device for generating localized directed gravity fields, which would also be very useful for aiding maneuvering in spacecrafts.  Since he saves it for an emergency, it probably requires a lot of energy to operate, especially when using it to counteract a planet's gravity.
We never see the inside of ET's ship, but my guess is that it is probably more like the ISS than the Enterprise - narrow hallways, lots of handholds, and no ship-wide artificial gravity.  Instead of spending huge amounts of effort and energy to make the ship seem like their home, his species probably found it more efficient to change the astronauts.
Comment: E.T.'s feet don't appear to have opposable digits, and in zero-g, legs and arms should become similarly lengthened.  The legs are entirely too bulky to be the result of zero-g atrophy.  In addition, if you have the energy to propel a starship, then adding a bit of lighting is a drop in the bucket.  The eyes would most likely have evolved long before space travel.