Do trigonometry mentally

Question: I know that sound a bit stupid, but is there a way to calculate basic trigonometric functions mentally like:
$$
\sin(x)
$$
$$
\cos(x)
$$
$$
\tan(x)
$$
$$
\arcsin(x)
$$
$$
\arccos(x)
$$
$$
\arctan(x)
$$
I know it's a lot of functions, but if you can give me a simple and nice writen answer, that would be very nice!
Comment: You can for example calculate them with power series expansions or using geometry, looking at the unit circle or triangles.
Comment: There is no real point in being able to calculate these functions mentally, really.
Comment: @MarianoSuárez-Álvarez I know, but I want just a simple method to approximate those functions
Comment: You google "sin(23 degrees)" and you get an approximation.
Comment: If you remove the "mentally" part then the question becomes one that has interest.
Comment: @MarianoSuárez-Álvarez if you want to answer this question without the mentally, do it, that would be great
Comment: One might consider a digital calculation to be "mental" if mental just means not done using physical writing with pen or book. Empirically the human mind is just electrical signals and a computer is the same. Alternately one could memorize a table of values.
Answer: You can use the Taylor Series expansion. For example, $$\sin x= x - \frac{x^3}{3!}+\frac{x^5}{5!}+\dots$$
So as $x \approx 0$ $\sin x \approx x-\frac{x^3}{6}$. Since the error grows a bit larger as $x$ grows, you may also want to use the fact that $\sin x$ is a periodic function. Thus $$\sin(x+2 \pi)=\sin x$$
You can calculate $\cos$ and other trigonometric functions in similar ways. For $\cos$, the expansion is $$\cos x = 1-\frac{x^2}{2!}+\frac{x^4}{4!}-\dots$$
And since $\tan x =\frac{\sin x}{\cos x}$, you can calculate the tangent as well.  Other tools you could use include the double angle formula, and you can approximate using well known values such as $$\sin \frac{\pi}{4}=\frac{\sqrt{2}}{2}, \quad  \sin \frac{\pi}{6}=\frac{1}{2}, \quad \sin \frac{\pi}{3}=\frac{\sqrt{3}}{2}$$
Or, somewhat less known but still famous $$\sin \frac{\pi}{12}=\frac{\sqrt{6}-\sqrt{2}}{4}$$
For the inverse trigonometric functions, the Taylor series for $\arcsin$ is as follows $$\arcsin x=x+\frac{1!!}{2!!}\frac{x^3}{3}+\frac{3!!}{4!!}\frac{x^5}{5}+\dots$$Where $n!!$ is the double factorial.Then, we have that $\arccos x=\frac{\pi}{2}-\arcsin x$. Using these, we can approximate the values required.
Comment: Also double angle formulas can let you push closer to 0 giving better approximations.
Comment: @mathreadler Yes, they do.
Comment: Yes, but, can you give me the "similar ways"?
Comment: @ArthurGuiot See [here](http://www.efunda.com/math/taylor_series/trig.cfm) and [here](http://www.efunda.com/math/taylor_series/inverse_trig.cfm)
Comment: @ArthurGuiot Does my edit address your question?
Comment: @S.C.B. Your edit almost complete my question, do the arcsin, arccos, and arctan, and I will click on the check button :) but thanks a lot
Comment: @ArthurGuiot Editted. Your welcome.
Answer: Convert the argument to a multiple of $\pi/2\approx1.57$, i.e. express the angle in "quadrants". It is an easy matter to reduce to the first quadrant.
Then
$$\cos x^*\approx 1-x^2$$ is a resonable approximation ($<5\%$ maximum error, green curve).
You can get better with an extra term,
$$\cos x^*\approx(1-x^2)\left(1-\frac{\pi^2-8}8x^2\right)\approx(1-x^2)\left(1-\frac7{30}x^2\right).$$
($<0.3\%$, blue curve.)

The sine is obtained from $\sin x^*=\cos(1-x^*)$ and the tangent from the ratio. The arc sine/cosine can be drawn form the first approximation, but require a square root extraction, which is uneasy.
Comment: This looks remarkably similar to my own [empirical approximation](http://math.stackexchange.com/questions/976462).
Comment: @Lucian: no surprise, these are mere polynomial approximations with some tradeoff between accuracy and coefficient simplicity.
Answer: Sorry, but it can't be done mentally. And I don't know about inverse functions but I can give you my simple method to calculate $\sin$ of any angle upto at least one digit of accuracy. First, convert your angle to radians if it's in degrees.
If you want to calculate $\sin\theta$ where $\theta$ is in degrees, then first calculate $x=\frac{\pi\theta}{180}$
Now, if $\theta$ lies between 0 and 22.5 degrees, then $\sin\theta=x$ approximately. The accuracy decreases as the angle increases.
If $\theta$ lies between 22.5 and 45 degrees, then $\sin\theta=x\sqrt{1-(\frac{x}{2})^2}$ approximately. The closer $\theta$ is to 45 degrees, the lesser the accuracy.
If $\theta$ lies between 45 and 67.5 degrees, then use $\sin\theta=\frac{1}{\sqrt{2}}(x-\frac{\pi}{4}+\sqrt{1-(x-\frac{\pi}{4})^2})$. Accuracy decreases as $\theta$ gets closer to 67.5 degrees.
If $\theta$ lies between 67.5 and 90 degrees, use $\sin\theta=\sqrt{1-(\frac{\pi}{2}-x)^2}$. Accuracy increases as $\theta$ gets closer to 90 degrees.

Do trigonometry mentally


How to log out off yu-gi-oh duel links account / gmail

Question: I started this game yesterday, now my brother wants to play this game on his own account but on the same device (tablet). We tried already just another login on another gmail account, but he is still on my account and can use my cards and see the progress. So how we can play this game on our own accounts?
Comment: You can self-answer your question so that others can find the answer.
Answer: You cannot log out of an account because your data is stored on the konami servers and that is linked to your device so no matter what you do. you cannot log out.


How to install ssh private key?

Question: I used to have old laptop with Ubuntu desktop 18.04 and dell server with Ubuntu server 18.04. On the laptop and server was installed ssh keys and I could connect to server without password. Now I got new laptop with installed Ubuntu Desktop 18.04 on it,  but can not connect to server through ssh. I have files private / public keys. How can I install them on my laptop to get connection with server?
Comment: Do you still have access to the old machine?
Comment: Yes I do have access.
Answer: You don't "install" the keys to use ssh, you just reference the private key. For example:
ssh -i ~/my_private_key_file my_user_name@my_server_name

Note that any time your username is the same on both your local and remote machines, you can eliminate your user name and just:
ssh -i ~/my_private_key_file my_server_name

It's even more convenient if you edit your ~/.ssh/config file and add:
Host any_name
    HostName my_server_name
    User my_user_name
    IdentityFile ~/my_private_key_file

If you've done the above, then you can ssh in like this:
ssh any_name

You can also use keychain. Keychain lets you load your keyfile into memory like this:
apt install keychain

Then
keychain
ssh-add my_private_key_file

With your key file loaded into memory as above, then you simply:
ssh my_user_name@my_server_name

You don't have to load the key into keychain each time. The key will stay in memory even when you close the terminal from which you ran it. You only lose it when you log out or reboot.
And finally, the "dream setup" is this:
Load your keyfile into keychain when you first log into your local machine.
Add the following into your .ssh/config file (notice the absence of the "Identity File" line)
Host any_name
    HostName my_server_name
    User my_user_name

Then ssh by:
ssh any_name

Answer: If you still have access to the old machine, just copy the ~/.ssh directory to the new machine and everything should work just as it did before. For example, if you can ssh (with a password) from the old machine to the new one, just run
user@oldMachine $ scp -r ~/.ssh user@newMachine ~/.ssh

If not, just copy it using a USB stick or even email it to yourself. Once you have the ~/.ssh directory copied, everything should work as it did before.
If you cannot do this for some reason, setting up passwordless ssh again is trivial. Just follow the instructions in this answer: https://askubuntu.com/a/46935/85695.

How to install ssh private key?


What is the proper procedure for showering in a gym locker room?

Question: This is going to sound like a stupid question. I apologize. But I've had it on my mind for a while and it needed to be asked.
My question is: how do you use the shower at the locker room at the gym?
I told you it was stupid.
But really, I've had gym memberships for a total of about 5 years during my life (not consecutive). I've gone frequently and worked out, but I've never used the showers there. Why not? Honestly, I've just been too nervous about it. It's not so much public nudity itself that makes me nervous. It does make me feel weird and a little self conscious to take my clothes off in a room with other people in it, but I don't think other people really care that much. What does worry me though is the possibility of committing some kind of social faux pas or perhaps even exposing myself to some kind of safety hazard.
Some of the things that have run through my mind as I contemplate taking a shower at the gym:

Where do I keep my clothes?
If in a locker, should I wear a towel between the shower and the locker?
Where do I keep the towel while I'm in the shower? Not every place I've been to has somewhere to hang it.
If there are no private showers, is it normal to shower in a bathing suit or similar attire? My current gym has private shower stalls with curtains, but I've been to gyms where the showers were more community style.
Where do I keep my cell phone/wallet/keys? I can't really bring them with me into the shower, so I suppose I'd have to keep them in the locker. But is that safe? If someone broke into my locker while I was in the shower, I'd lose everything valuable and I'd have no clothes.
If I use a shower that strangers have used, are there any possible health repercussions? Do I need to wear sandals to protect against athlete's foot, for example?
Is it normal/OK to perform other grooming functions, such as shaving, or brushing your teeth, in a gym locker room?
Etc

So again, in summary, what is the safest and most socially acceptable way to use a locker room at the gym?
It does surprise me how anxious I feel about this, considering I'm usually pretty laid back about most things. I have been to the hot springs and even bath houses in Japan, when I was there visiting friends. But I felt less anxious about that because I was accompanying people who knew what they were doing, and I just did my best to imitate them. When I go to the gym locker room by myself I feel completely out-of-sorts. I feel like everybody else in the world has read some secret manual about how to deal with this and nobody ever handed me a copy. Please help!
If there's some cultural ambiguity about social customs, please assume for the purposes of this question that we're talking about the United States.
Comment: Look at the ceiling and don't drop your soap are the two rules I follow.
Comment: +1 I have exactly the same problem. As an extremely partial answer to your question, my gym explicitly encourages men to do their grooming right in the locker room.
Comment: It is about etiquette and personal hygiene.
Comment: I had the same fear, but I dared to shower once naked and no looking back now. Here in Germany no one cares if you get a boner too.
Comment: Just make sure that you don't go up and tickle anyone's balls from behind, because [that's sexual harassment](https://youtu.be/ap_XoAVvbQg?t=14).
Answer: Short answer is this: when in doubt, ask management.  A longer answer includes some general principles:

Use your locker to store clothes, and anything you don't want in the shower with you.  Lock your locker and take the key with you (if it's not a combination lock).
Wear a towel around your waist going from the locker to the shower.  While no-one is likely checking you out, you don't want to advertise either.
Hang your towel on the shower stall door or on top of the shower head if there isn't a towel hook.

As far as community style showers go, it really depends on your comfort level.  More than likely in a gym most people in the shower area with you don't really want to see you.  As long as you aren't looking all around and focusing on getting clean, you won't cause any breach of etiquette.
As far as clothing in the shower goes, what is the purpose of the shower area in your gym?  If it is simply to rinse before and after going to the pool, use a bathing suit.  If it is to clean off the sweat from intense training, being in the buff is OK.
As far as health risks are concerned, evaluate the cleanliness of the shower area.  Gyms that routinely disinfect the shower areas will be about as safe as your home shower would be.  However, if you see evidence of less than stellar upkeep, keep some flip flops on.  Use soap and warm water.  Anything more falls under safety concerns.
Last, but not least, if showering at home suits you best, do it.
Comment: *Always* use shower shoes, e.g. flip flops.  Always.
Answer: I've been in and around the military for 25 years and I've used gym showers for more than 30. Despite this, I still have my own questions about the unwritten etiquette of showering in gym locker rooms.
The etiquette differs greatly based on sexual orientation, but the universal rules are these:
Golden Rule: Boners make public showers awkward.
Other Rules:
1) Always shower before and after using the swimming pool or sauna (wet or dry).
2) Always wear a towel when going to and from the showers (and/or the sauna). Some guys may want to see you in the buff, but none are going to tell you. The rest of the guys simply don't want to see you naked.
3) Wear flip flops or some other form of foot protection to protect you and others from the spread of foot fungus and other unmentionables (see rules 8 and 9).
4) Talking is fine, in or out of the showers. Just don't talk about sex, women, other men, or anything that is likely to cause arousal. See Golden Rule.
5) Even if someone is putting on a show for you, don't stare (especially if it arouses you -- see Golden Rule).
6) Keep your hands to yourself. Touch only what is yours. Sharing a bottle of shampoo or body wash is okay, but don't make physical contact with the other person.
7) Don't tug on your junk, not even a little. Even if it's cold and drafty in the showers and you are self-conscious about shrinkage. Even though we're not looking, per se, all guys can all tell when someone has been tugging on it to compensate for cold-air shrinkage. Don't spend any more time or attention on your junk than is required to wash and rinse it.
8) Don't masturbate in the shower. Most people don't want to see you. Even those who do want to see you don't want to step in your man goo.
9) Don't pee in the showers. No one wants to smell the acrid smell of your urine. And we don't want to watch it swirl down the drain with your shampoo suds. And we don't want to step in it, either.
10) Take all your stuff with you. If you shave in the shower or use the last of your body wash/shampoo, take your trash with you. If you're one of those peculiar types who wears his undies, jock strap, or gym shorts to the showers, make sure you take your crotch sweat-soaked clothing with you.
11) Dry off as much as possible in the shower and keep your butt facing the wall while you do it. Because very few guys want to sit on the bench and see your naked butt or junk at eye level while you dry yourself off.
12) Don't pay compliments to others on their bodies or body parts. If a guy has great definition in his pecs, delts, quads, or (especially) glutes, keep it to yourself or mention it outside the locker room. Even as much as I enjoy having someone flirt with me, I don't want it to come from the guy next to me...in the locker room at the gym. It's creepy.
If a guy is straight, remember the Golden Rule. If a guy is not straight (gay, bi, curious, etc.), there are caveats to the rules, but only if it is known that the other guy is not straight.
These are the rules I have come up with based on 30 years worth of observations and experience.
Comment: For Number 11, I'd argue to keep ones crotch facing the wall so as to create less of a potential show, but that may be a personal preference.
Comment: +1 I'd like to upvote this answer **twice** . It's so true and hilarious.
Answer: Locker rooms are a comfortable space for most men, and a terrifying space for some.
If you are in the latter category, don't use the locker room or use it but don't shower.
The good news is as long as you don't stare it is hard to violate any sacred rules, because there are none.
Having showered in dozens of different locker rooms, layouts vary.  Regardless of shower type (stalls or open), the basic procedure is the same.
You put your street gear in the locker and go work out.  When you are dine you return to the locker and get naked, stowing your sweaty gym gear in your gym bag/back pack.  I have showered in gyms 4 to 7 days a week for more than ten years and owing to work travel I go to lots of gyms.  I have seen lots of guys skip the shower but I have never seen one  put on a swim suit to shower in.
Once you are stripped, most guys put the towel around their waist as they walk to the shower area.  Others kinda just hold it in front of them.  Some hold the towel at their side or put it over the shoulder.  There is no rule.
Once you get to the shower area, there are usually hooks in an area near the stalls, right outside the communal shower room or sometimes in the shower room on the wall opposite the shower heads.  A few places have hooks inside the oversized shower stalls.  You just look around and put your towel where others put it.
In the shower there are no special rules except no staring.  No staring doesn't mean you can't look at people.  You should look your shower mates in the eye, however.  If it is an open shower you shoul pick am open shower head as far distant from the other users as possible.  This gives others space, but it is not an inviolable rule,  One guy at my gym for some reason apparently needs to use the same shower head, and if the shower is empty except for me, upon entering he will take the head right next to mine if it is the one he likes.  I figured this out at some point and if I see him in the gym and expect our showers will overlap, I go to a head on the otherside of the room.
You can and should bring your own shampoo or body wash.  Very few bring in bar soap.
The trip back to the locker is the same as the trip into the showers.  If you want, you can shave, etc.  Some guys do this in a towel.  Some do it in underwear only.  Some do it in pants but no shirt.  Some do it fully clothed.  A few guys like to do it naked.  It is a choice.
Answer: Wear a wrap to the shower and back, wear sandals, that's about it. If it's too much, don't bother.
Keep your clothes/etc. in your locker, use either your own towel (my preference) or the gym's for a towel, if the towel is big enough you can wrap with it, otherwise bring something meant specifically to wrap.
Don't make a mountain out of a molehill.
Answer: Using the shower at the gym ultimately depends on what type of environment it is. For example, my gym has a separate stalls for every shower. Between the stall door and the shower is a changing area. I keep all my belongings in a bag and hang them on the door. Once the door is closed and the shower area is concealed, it's up to me how I wish to conduct myself behind that door. I wear flipflops and give the shower time to rinse itself for a minute or so before I step in. I try not to touch any surfaces. I walk into the stall dressed and I exit the stall dressed. I don't care to have any accidental mental images of other gym members naked, so I return the courtesy. Some people walk around entirely naked - I feel that's rude in an environment that is designed for modesty. But, hey - that's me - plenty of people are entirely ok with public nudity.
All I know, it's more comfortable getting into my car all fresh and clean than dirty and sweaty. I don't think I'd use the shower area if it was entirely open at the gym - it would be one thing, perhaps, if I was on a sports team and it was a team-shower - but with the general public of which there are no relationships? I just think it's creepy.
Answer: I live in Europe, but it's always good to compare practices. I can't imagine not getting clean after exercise and going on public transport (yes, we have it) or - heaven forbid - into the office without using shared facilities to get thoroughly clean. It also means you can lower your water usage at home and hence utility bills.

Q1) Where do I keep my clothes?

I always lock them away. I haven't seen a changing room without a locker since leaving primary school.

Q2) If in a locker, should I wear a towel between the shower and the
  locker?

I wouldn't wear one from the locker to the shower, as you're going to be drying yourself with the same towel and don't want sweat/chlorine on the towel. I'd strip and go nude to the shower with the towel separate/in a bag (along with shower gel). For the return journey it's a matter of taste and what you're comfortable with. Follow what others are doing and you can't go wrong.

Q3) Where do I keep the towel while I'm in the shower? Not every place
  I've been to has somewhere to hang it.

In a bag preferably on a hook at the last convenient place before the shower. My main concern would be spreading water around unnecessarily (rather than getting the towel nicked), so dry at or close to the place where you shower to avoid getting the place wet.

Q4) If there are no private showers, is it normal to shower in a
  bathing suit or similar attire? My current gym has private shower
  stalls with curtains, but I've been to gyms where the showers were
  more community style.

If it's a gym with no swimming pool, I don't know why you'd have a bathing suit. Gym changing rooms are in my experience always single sex and with no children present, so I wouldn't even consider not showering nude in an open shower. In swimming pools there may be children present. Not that this normally changes my behavior, but I'm European :D Again, follow what others are doing and you'll be safe.

Q5) Where do I keep my cell phone/wallet/keys? I can't really bring
  them with me into the shower, so I suppose I'd have to keep them in
  the locker. But is that safe? If someone broke into my locker while I
  was in the shower, I'd lose everything valuable and I'd have no
  clothes.

Use your judgement as to how safe the lockers are. I have locked everything except the towel and shower gel for years and nothing ever happened. Sometimes you can leave valuables (wallet/phone/keys in a safe rather than in the locker.
If I use a shower that strangers have used, are there any possible health repercussions?
See below - wear flip flops if you're concerned.

Q6) Do I need to wear sandals to protect against athlete's foot, for
  example? Sandals are a good precaution, though might not be necessary.

It depends how clean the place is. Thoroughly drying your feet and
changing clothes frequently are equally (if not more) important for
preventing these issues.

Q7) Is it normal/OK to perform other grooming functions, such as
  shaving, or brushing your teeth, in a gym locker room?

Sadly it is normal at my pool, though fortunately it doesn't happen at the gym. I see no reason why anyone should shave (and block the sink for other users for many minutes) at a pool or gym. The shaving is not limited to the facial area, have seen body hair, head (scalp) though fortunately not pubic hair yet.
I like to give my mobile phone a rest when in the gym. If someone wants to take an illicit picture of my average mid-30s naked body then I can't say I'm going to lose any sleep over it.
Enjoy the exercise along with the showering and changing at the end. Once you start then you'll find it normal and quite a liberating experience. I've bumped into colleagues including my supervisor - nude in the shower on more than one occasion. :)
Edit: I meant gym changing rooms are a single sex environment - not the gyms themselves. My gym is mixed sex, but the showers and changing rooms are segregated - as is the case in all gyms and pools I've ever been to apart from the Changing Village madness I saw back in the UK.
Comment: "Gyms are normally single sex" - That's interesting. Here in Michigan, USA there are a few women-only gyms, but as far as I am aware there isn't even one men-only gym in my area. Every gym I've personally been to has been unisex. Of course, the locker rooms themselves are divided by gender.
Answer: Take off all your clothing at your locker, putting all dirty/sweaty clothing in a plastic bag (keeps other things from getting soiled/smelly), lock it, then head for the showers with perhaps only a washcloth (or scrub puff or similar) and possibly a towel...  I say possibly, as towels get picked-up & moved, and often used or stolen by others.
DO NOT "wear" a towel!  You'll be getting your towel nearly as soiled (sweaty at least) by your un-clean body, plus it really sends the wrong message that nudity is somehow wrong, immoral, improper, or whatever.  (Did you know "gym" comes from the Greek word "gymnos", which means "place of nudity"?)
If you take a towel or other stuff, see if you cannot keep it on a hook, or as needed, over the pipe behind the showerhead and/or shower handle(s).  -If your shower is in a partitioned stall of some kind, you may (if not too high) be able to keep items on top of a panel, but DO NOT flop/fling them over, as you'll be spraying the guy next to you if you do!  (That's rude, and might get in the guy's eyes or give him a rash or something depending on the presence of soap/shampoo.)
Wearing a swimsuit is not really proper...  It really just tells guys you're ashamed of your penis/genitals, and will cause some to pay you even more attention, wondering if what you have is really worth looking at.  -Not to mention you cannot wash covered parts and rinse them adequately, AND the fact that soap that's good for you is bad for your clothing - it will cause fabrics to fade and fall apart more quickly.  (This is no joke!)
As for valuables, don't bring things you do not need...  If you're out only for the gym and returning home immediately, leave the phone, music player, etc at home if at all possible.  -Some gyms may have more secure coin-op lockers up front, near the desk or near the workout area, where break-ins are less likely to happen.  Some gyms will also allow you to have the desk employees hold things in a drawer there, but this is not really secure at all and it's dependent on you remembering things and keeping the employees honest.  -If you "have" to have the items in the gym, then keep them in your locker and use a more secure lock that can't be picked (no keys), is tempered/hardened, and preferably uses combination wheels (4 or more is best) or a magnetic key.  Taking a shorter shower so you can check back on your locker quicker may be best, as well as drying lightly in the shower area and more thoroughly at your locker so you can keep an eye on it.
(BTW, DO NOT take electronics into the sauna or steam room, as you will slowly damage them...  It's too hot and/or humid and they are not normally made for such!)
Wearing plastic slide sandals is best in a locker room environment, not just in the shower or wet areas, but in the locker room itself.  -Floors there are usually not cleaned well, and certainly not enough to keep much dirt off it, not to mention keep mold/fungus and bacteria from growing!  DO NOT step on the floor anywhere there if you have the slightest issue with "athlete's fungus".
Also on the same note, ALWAYS put CLEAN socks on before your underwear and/or pants/shorts.  If you don't, you can transfer athlete's fungus from your ft. to your crotch area, which then gives you "jock itch".  -This is the best idea, no matter where you are dressing!
Many shave before or during a shower, no mater where they shower, to give anyone they may meet (to them) a better appearance of them, or to rid themselves of that "5 o'clock shadow".  However, IMHO, brushing your teeth is a bit much...  After all, if you didn't recently have a meal (elsewhere, presumable) and not brush afterwards, why wait until showering to correct the oversight?  Perhaps if you're leaving there for a date, you might want to, but otherwise is there a need to do it there???  I feel likewise on body shaving.  -Take the time to do this in a more private space (at home) if you must do it.
I run a forum for guys on Yahoo Groups for guys that have trouble with body-shyness issues and help for same, so if you're in that kind of position at all or looking to help those with same, check it out:
https://groups.yahoo.com/neo/groups/WHYP/info
Answer: The USA is the only country I've been in where nudity in men's locker rooms is almost seen as obscenity and it's totally ridiculous. Locker rooms are meant for changing clothes, showering, taking a sauna, etc. There will be nudity and a nude body is nothing to be ashamed of or frightened by. Every man has a penis I don't care one bit what yours looks like or its size. Neither do I care one iota if you see mine. For God's sake- it's a locker room and there will be nudity. Don't fret about it. Enjoy your time at the gym, please shower before going into the pool or hot tub. If you are that upset about seeing another man nude then work out at home.
Comment: Don't you take The Lord's name in vain! lol. But seriously, the OP stated quite clearly that 'it's not so much public nudity itself'. So your answer kinda missed the point.


MFC> Connecting a dialog to a dialog class

Question: I have defined a new dialog and its controls in an already existing resource file. I have also created a new file which will handle the events being generated from this dialog. But I am not sure how to connect these two.
Is the statement enum { IDD=IDD_NEW_DIALOG }; all that is required to connect the two?  Or should we add some other statement?
Answer: The way this is usually done in MFC is to define a dialog template in the resource editor (as you've done), then in C++ derive a class from CDialog and associate it with the dialog template (which it sounds like you've done - it's not entirely clear).
What actually associates the two is the constructor for your CDialog code. If you look at dialog related code auto-generated by the MFC class wizard, you'll see in the constructor implementation something like this:
CMyDlg::CMyDlg(CWnd* pParent /*=NULL*/) : CDialog(CMyDlg::IDD, pParent)

where CMyDlg::IDD is defined as an enumeration with a value of your new dialog template's identifier. It's this that makes it all happen, not the declaration of the enum. You could modify it to
CMyDlg::CMyDlg(CWnd* pParent /*=NULL*/) : CDialog(IDD_NEW_DIALOG, pParent)

and it will still work (assuming IDD_NEW_DIALOG is the template id of your dialog in the resources), as all that's happening is the dialog id is being passed into the constructor.
In general, it's always worth remembering that, despite initial appearances, MFC does not bind to Windows through bits of compiler magic - it's all done with C++ and a few macros.
EDIT: DIALOGEX and DIALOG declare slightly difference dialog resource formats that Windows understands: the former is newer than the latter. However both have been around since at least Windows 95, so it's not a very significant distinction.
Comment: Thanks for the reply. I derive the class from a base class which derives from CDialog. So i guess this takes care of the stuff.
Answer: That's all that is needed when you create the dialog through the dialog class (DoModal(), or Create for a non-modal dialog), which is the normal way to go.
You of course need to inherit from CDialog, and add a message map to route the messages to your ewvent handler functions.
Answer: Use class wizard to create a class for newly created dialog. ctrl+w is the shortcut key from UI resource view.


Polygon vs Traces

Question: I am designing a 4 layer PCB. For high currents in the inner layers, should I use polygons or traces? Trace width can be defined by the current requirement from the trace width calculator but what about polygons? When to use polygons and how to decide it's width/area?
Answer:
When to use polygons

Use a polygon when its easier to do it that way. For example, when other features (vias, other traces, etc) prevent fitting a trace of the required width.

and how to decide it's width/area?

As a general rule you should try to make the width at least the same as what you calculated with the trace width calculator. However you can allow short segments to be narrower because heat will propagate lengthwise to other segments that are wider.
Comment: @Andr7, outer layer typically comes out 1.5 oz due to plating added when plating vias. There shouldn't be any problem with using 2 oz on inner layers. Note inner layers typically need to be thicker to carry the same current due to not being exposed to air.
Comment: For trace widths upto 6cms, how should I plan the polygon?
Comment: @Andr7, plan it so that it connects from where the current comes from to where it has to go to, and try to make it 6 cm wide. If you need to use vias to connect from or to the polygon, consider using several vias in parallel to handle the kind of currents that require a 6 cm trace without excessive voltage drop.
Comment: Can I do inner layers as 2 oz and top -bottom and 1 oz to decrease the widths? It is difficult to make wide polygons with multiple nets on the same layer

Polygon vs Traces


CiviMobile local timezone

Question: When I create activities etc. on CiviMobile in my Time Zone I am in it displays as 9 hours later.  Currently I am -7 GMT and when setting an activity on the app it automatically changes it to +2 GMT (9 hours ahead of my time zone). When I look on CiviCRM, the activities I created in CiviMobile are 9 hours ahead there too. I'm using the latest CiviMobile on and iPhone. How do I get CiviMobile to use the time/time zone on my phone?
Answer: Jerry, Welcome to CiviCRM stackexchange, your civicrm database stores certain fields with data-type "DATETIME". To improve timezone support, you may want to change these from "DATETIME" to "TIMESTAMP".
For further discussion, please visit https://github.com/civicrm/org.civicrm.doctorwhen
Answer: This is a workaround, not a solution:
Comment out the time_zone_utc_offset in PublicSettings.php, in Cms.php and in CiviMobileSystem.php
CiviMobile takes the server timezone-settings. Depending on what has been configured there, the result can be misleading...

CiviMobile local timezone


SharePoint List to Access

Question: I have a SharePoint Lists linked to an Access Database. Can you keep the information that was deleted in the SharePoint List in the Access database?
Answer: A SharePoint list can be "saved" in Access a few ways:

When connecting to the SharePoint list, you are asked if you want to "link" the list or "import" the list. If you import the list it will be just as if you imported an excel document or a text file. A copy of the data is stored locally. Changes to the local data are not reflected in the source, changes in the source are not reflected in the local data.
Use the "convert to local table" available from the right-click context menu of a linked sharepoint list. This changes a "linked" list to an "imported" list per #1.
Use the non-2010+ caching mechanism which enables you to "work offline". To do this, go to File -> Options -> Current Database -> Caching Web Service and SharePoint Tables and uncheck Use the cache format that is compatible with Microsoft Access 2010 and Later. Once you do this, you will see a new option on the External Data ribbon tab that allows you to work offline and manually choose when to synch your cached data.

https://support.office.com/en-ca/article/Work-offline-with-tables-that-are-linked-to-SharePoint-lists-5d66594a-6176-4a25-a198-320f13ccf41e
You can always export the current contents of a list, query or table to a file at any time if you plan on deleting data but want to keep a copy.

SharePoint List to Access


Can I just 'dd' from one HDD to another to clone HDD

Question: I wanted to know if I could just use Linux command 'dd' to make a copy of a hard drive. The hard drive has windows XP and the goal is to move data from a smaller HDD to this larger one without having to explicitly re-install windows. I personally don't know enough to know if this has the potential to screw up the file system. I also don't know if this works between different models of HDDs.
Answer: Yup. dd operates beneath the file system. You can dup partitions or whole drives, depending on what device nodes you use.
You may want to research the optimal "bs" (block size) to use for your hardware because if you get it wrong, this can take forever.
Comment: BTW... I've used this very technique to upgrade my TiVo hard drive.
Answer: Yes, you can do this, with a couple things to be aware of.
Different brand hard drives (or even different models of the same brand) may not be the exact same size.  You should check the real size of the block devices to verify the target drive is the same size or larger than the source drive.  As long as it is, you are good to go.
If the target drive happens to be larger, after you've cloned the drive you can use gparted to expand the partition to fill the drive.
In fact, you could use gparted to shrink the source partition and then copy it to the target drive if the target drive happens to be smaller.
As dicoroce mentioned, you can also copy just partitions instead of an entire drive.  Just be aware that if you only copy the partition, you will have to reinstall the MBR (though that is trivial)
Answer: If I'm not mistaken, one very nice feature of GParted is the ability to correctly resize an NTFS partition that has Windows installed, by updating some magic number somewhere. What this means for you is that you'll (probably) be able to expand the partition to fill the whole drive without worrying about confusing Windows.
Answer: You should be fine.  Plus, if for some reason you have a problem you'll still have the original (smaller) drive as a fall back.


Gift Aid extensions compatible with 5.6.0?

Question: Are the Gift Aid extensions compatible with 5.6.0?  I'm planning to upgrade a client soon - they are on 5.1.2.
Answer: Andy,
If it works for 5.1.2 than definitely it should work for 5.6 since there is no major changes in financial bit of code cleanup and fixes. However its a good practice to test on the staging environment before going live.
HTH
Pradeep


Where can I share my custom scripts?

Question: I made a set of custom scripts for Ubuntu. I wish to share these on the Internet. Which services for sharing code with other users are available ?
Comment: https://github.com/ is kinda always the way to go. Or https://launchpad.net/
Comment: I'm voting to close this question as off-topic because it is not about Ubuntu but about sharing scripts online.
Answer: There's several options , which differ in their purpose and complexity. You may choose whichever you wish.

Ubuntu pastebin: http://paste.ubuntu.com is simplest approach to sharing, but  also the worst. The links aren't permanent, as far as I know, and you can only paste code, i.e. you cannot edit it. If you want to just share script with a few friends, that's the way to go.
Ask Ubuntu itself is a good place to share solutions. Of course, the scripts  have to be within the scopes of question where you wanna post. As a benefit, if your code is found useful, community will upvote answers. Keep in mind that anything you post is under creative commons license, so expect people will have essentially full access to the code. If you want to have it copyrighted, you can use explicit license in the script ( preferably open source one).
Software repository wesbites, such as GitHub, GitLab, and SourceForge. Most famous is GitHub. This is one of the options that I personally use. It's not very complicated, you can get around only with the web interface alone. GitHub also has something known as Gists. You can publish a script as public or private gist, and give link to it. GitHub repository is more for a collection of specific files that tie in together somehow, and usually is for large applications. Feel free to see my gists and repositories.
Launchpad. This is somewhat a more complex option. Users can add your PPA and install the scripts via sudo apt-get install package-name. Follow launchpad's tutorials to get started. There's couple ways to upload code there( see discussion in comments below).  Use this as reference for creating deb  packages for single scripts - these can be imported to Launchpad and built using Launchpad before placing into PPA. IMHO, single script that is not over 100 lines , isn't worth putting into deb package and then on Launchpad. GitHub gist is simpler for small scripts.
Containers and snaps. This is also somewhat more advanced option. The big plus is portability. Most famous cross-platform container options are Docker and Snap packages. Docker has its own store: https://hub.docker.com/ I don't know about snaps,though. To my knowledge there is no app store for those.
Comment: In addition to the other repository wesbites mentioned, there is also [Bitbucket](http://bitbucket.org).
Comment: Nice overview! One thing: for a ppa on launchpad, I only upload the changes file, no built .deb packages needed.
Comment: @JacobVlijm well, your setup is different from mine slightly. The way I do is import my stuff from github and build deb packages on launchpad.  Other devs might have different approach,too.
Comment: Absolutely, only referring to *"you have to upload script as deb package"*, but again, great overview, and a nice question.
Answer: GitHub is a good choice of sharing code.
Answer: GitHub is a great place for sharing code - But be sure to include a description of the scripts, how to use them and what their primary function is.
If your intention is to share your work and allow others to use them you will have to enable them to understand your scripts easily. You may also find that members of the community who use your scripts offer to contribute improvements and offer you support with updating and fixing any issues that may arise.

Where can I share my custom scripts?


Civilian Aviation Engineer on BSG

Question: What happened to the civilian aviation engineer from the Pegasus? Was he killed in an episode and I've just forgotten?
Answer: The "civilian aviation engineer" is Peter Laird from the Pegasus first replaced Tyrol as deck chief under orders from Admiral Cain - this is temporary and Tyrol is reinstated once Adama regains control of the fleet.
In season 4, Tyrol is demoted to specialist and Laird takes over as deck chief again until the mutiny led by Gaeta when he is killed by Zarek.
Source: http://en.battlestarwiki.org/wiki/Peter_Laird
Comment: Yes! I thought it might have been something like that! Now that you mention it, I think I remember this. His death seemed very nonchalant!
Answer: I think you're talking about the guy explaining that he's been the engineer who designed some specific model of engines? I don't remember him ever being shown or mentioned again.
To me he's been there just to support the fact that Pegasus had several civilians from "its" left behind civilian fleet. It's been an easy way to introduce this on crew level by the conversation between him and Tyrol raising some suspicion, while also showing that (most of) Galactica's crew treat everyone equally in contrast to Pegasus (where civilians were replaceable "tools" to fuel the war efforts).

Civilian Aviation Engineer on BSG


How to repair anchor holes and re-mount bathroom tissue dispenser

Question: I need to repair the holes where tissue bracket was installed, then re-mount it. About 3 inches behind the drywall are bricks. I thought about re-mounting it with 1 inch toggle bolts after repairing the holes with drywall tape.
Answer: If you  are repairing the wall and re-installing the tissue dispenser it would be wise to "multi-task" the repair.
Cut the damaged area to an opening smaller than the length of the dispensers screw holes. Cut a piece of 1/2 or 3/4 inch plywood 2 inches longer and slightly narrower than the cut you just made. Secure the plywood into the wall incision so that it will be held in place by a screw at each end of the wall opening (the plywood should extend an equal distance behind the drywall).
The newly installed plywood can now be used to attach a drywall plug and then the dispenser.
Comment: Any criticism for the down vote? No one wants to explain? Just like to remain anonymous?
Comment: idk, but Iggy didn't deserve *two* of them. Especially since it's the answer closest to removing the *how to* from the OP's title, that once removed answers itself: *repair anchor holes and re-mount bathroom tissue dispenser* - idk what's so hard about that if you know how to patch drywall, and install wall anchors.
Answer: It is going to be faster and hold longer if you cut drywall to studs and add a new piece of drywall in.  You will need less mud/tape and you won't worry about the expansion of the bricks pushing on the drywall/material - if you decided to just fill the space - which would probably show after time if not done right.
Answer: Go with your initial plan, unless people are using the dispenser as a grab-bar. If they're just old anchor screws holes of the 1/4" round about size, yank out the old anchors with needle nose pliers or send them through the drywall by palming or hammering a Phillips head screw driver (as big as the anchor's full face diameter) into the anchors. If you're re-mounting in the same spot then toggles should do great & vastly better than any in-drywall anchor...go with as big a toggle as will fit the dispenser or use what you have & just re-do it down the road if they were too small to hold up. I'm assuming the dispenser would cover any ugliness of hole enlargement. If you're re-locating, go at least 3" away from the old holes with your toggles & just fill the old holes a couple of times with compound for primer & paint.


Do laws of black hole mechanics depend on dimensionality?

Question: Unfortunately I'm not very familiar with the proof methods of the laws of black hole mechanics/thermodynamics. Do they hold in any number of dimensions? Are there any "hidden" assumptions? I'm thinking natural assumptions like asymptotic flatness (which would not hold for AdS black holes), or cosmic censorship (which I believe is violated in $D\geq 5$). Or are the laws simply general statements about event horizons?
Answer: The mass-energy, radius, entropy, lifetime etc. are related with power laws whose exponents depend on not only $D$ but in some cases also the geometry. For example, which $p$ gives the entropy-energy relation $S\propto E^p$? If the universe is otherwise Minkowski, $p=\frac{D}{D-2}$; if it's anti-de Sitter, $p=\frac{D-2}{D-1}$. As explained here, the former indicates quantum gravity is non-renormalisable while the latter motivates interest in the AdS/CFT correspondence.


Update Sharepoint 2010 to SP2

Question: After updating it to SP2, what do I need to check to be sure everything still works fine? It could be nice to write a checklist.
Answer: On MSDN there is a nice document, Software updates overview.
Wether you build a new farm or upgrade a farm always review the result documentation created by the proces:

The (upgrade) log files
SP2010 Products and Technologie Configuration Wizard (PSconfig.exe) PSCDiagnositics log file
Central Administration site check update status page

You can use the Test-SPContentDatabase cmdlet to check the status and health of a contentdatabase
Ofcourse validate the end-user experience and validate:

Verify themes, styles and images
Verify permissions
Identify broken links
Identify broken, missing of hidden Web Parts
Identify large lists that may be throttled by default
Answer: There is no prepared checklist, but from microsoft page of SP2 for SharePoint Server 2010 there is only one known issue :

After you upgrade the SharePoint Web Front End (WFE) from Windows
Server 2008 (R2) to Windows Server 2012, certain SharePoint
Designer-customized views that have custom XSL templates may be
broken. Moreover, the update can compromise server responsiveness. To
resolve this issue, you can install the SharePoint Server update from
June 2013 or a later version Cumulative Update (CU) after you upgrade
the operating system.

And you can check this post where people found problems during installation of SP2.
Answer: You should check grouped list items. SP2 had a  problem to display grouped list items. You can find a hotfix for this issue.
Answer: This is very vast area, it's depend how you want test it. I can share you my experience which will give you idea.
1) make sure you farm properly upgraded to new build number
2) from CA, Upgrade and migration page> review database status....make sure all db upgraded and no action required.
3) from CA, manage server in farm...make sure all server status shows as no update required.
4)make sure time service & admin services running on all sharepoint servers.
5) test at least one site collection from each Web app and make sure no issue with that.
6)write some test case from end user stand a point...create a subsite in collection, create a new list, set alerts, test workflow, etc.
7)make sure all services applications you configured are running...from CA browse to services application page and then every service app you configured.
8) if you have a user profile service run full crawl
9) if you have search service, run crawl over here and also test search is working.
10)test each services app you configured.
11)if you have language packs then make sure those are also working.
12) also test the fix which introduced in the CU.
Comment: Thank you for all your answers, I'd like to accept them all. I choose this one only because it's the closest to a checklist.

Update Sharepoint 2010 to SP2


Google Wallet Problem

Question: I found out today my cc was under my friends google wallet instead of mine. I was wondering if I delete it from his wallet; will I be able to add it under mine and be capable of using it. I ask because when I go to remove it, it says "This card will no longer be available to use online or on your device", what exactly does that mean if anyone can tell me.
Answer: You can add the credit card to your Google Wallet account while leaving it in your friend's account. (My wife and I have each others card under both of our accounts.)
As for the "no longer available" message; that refers to their account only.
Answer: It means it won't be able to be used with that Wallet account anymore. You can still add the card to your Wallet account.

Google Wallet Problem


What's the difference between "livid", "full of wrath" and "enraged"?

Question: What's the difference between "I am livid", "I am full of wrath" and "I am enraged"?
Comment: Well, one difference is that nobody uses _wrath_, and not many people use _enraged_ in everyday conversation. But there is no difference in the objective meaning, only in the register.
Answer: https://www.merriam-webster.com/dictionary/wrath
http://www.learnersdictionary.com/definition/enraged
https://www.merriam-webster.com/dictionary/livid
You will notice, the Merriam Webster definitions seem to be very similar.  In usage, I would say there is an order or strength.  From weakest to strongest Livid-Enrage-Wrath
Wrath is slightly archaic and invokes biblically retribution and punishment.
the root of Enrage is "rage" https://www.merriam-webster.com/dictionary/rage which has connotations of violence and uncontrollable anger.
Livid, at least where I have seen it used and used it myself, does not have these connotations.  In fact, I would expect to see it more used when there was an impotent anger, where the person who is angry knows they can't do anything about it and have to just put up with it.  "Daniel was livid when his boss took credit for his idea".


Alternate proofs of Immerman-Szelepcsenyi theorem

Question: Immerman and Szelepcsenyi independently proved that $NL=coNL$. Using their technique of inductive counting, Borodin et al proved that $SAC^i$ is closed under complementation, for $i > 0$. Prior to Reingold's theorem ($SL=L$), Nisan and Ta-Shma proved $SL=coSL$, using logspace uniform projection reductions. A 1996 paper of Alvarez and Greenlaw states "A proof of $NL=coNL$ using techniques similar to Nisan and Ta-Shma's has not been achieved although such a proof would be very interesting". I am wondering if such a proof is found in the last 14 years. Are there any other alternate proofs of $NL=coNL$ ?
Comment: A very similar style of proof is given by Reinhardt and Allender, "Making nondeterminism unambiguous" to prove that st-reachability graphs with a unique min-length path between s and t can be decided in UL \cap coUL.
Comment: @Derrick: could you elaborate in an answer?
Comment: @András : Reinhardt and Allender's paper uses inductive counting and isolation lemma to show that NL/poly = UL/poly i.e., in the context of nonuniform complexity, nondeterministic logspace bounded computation can be made unambiguous. This is a nice related result but doesn't deserve to be added as an answer.
Answer: Since we don't seem to have any answers, can I make a comment?
Suppose we are given $n$ bits, $X=x_1,\cdots,x_n$ and we have to complement each bit to get $\neg x_1,\cdots, \neg x_n.$ The only constraint is that the circuit that does so should be monotone. We obviously need some additional information to do this and here is one such.
Suppose $k$ is the number of ones in the input and somehow we have this as advice. Then it is easy to see that $\neg x_i = Th^{n-1}_{k}(X-x_i)$ (i.e., on all inputs except $x_i$). Of course, the construction is monotone.
With this construction, the motivation for inductive counting is clear (at least to me). It is worth asking what other advice would work? I don't know of any other. But this may hold the key to your question.
Comment: Just adding to this thread. The number of ones in the input can be "guessed" by a binary search and it can be shown therefore that in order to negate n bits, we only need $O(\log n)$ negations. This is a well-known [theorem of Markov](http://portal.acm.org/citation.cfm?id=320945") (for those who haven't seen it, it is a very nice exercise). In fact, for general functions $f$, one can limit the number of negations required to compute $f$ by the log of the number of times $f$ "changes sign" as we go from the all zeroes input to the all ones input [by Fischer, I think].
Comment: @Vinay, @Ramprasad : Thanks for beautiful insights.


Name of people inhabiting the Kingdom of Bonfrith?

Question: would people living in the Kingdom of Bonfrith be called Bonfrithians, Bonfrisians, or something else, according to correct grammar?
Comment: At the cannibal burger joint: Do you want bonfries with that?
Comment: Welcome to the site. When you have a moment check out the [help] to get an idea of expectations for good questions and answers.
Comment: I'm voting to close this question as off-topic because this is more about grammar and language usage than constructing a fictional language. If you want to design a language, this is the place to be, but if you want help with English usage, see the [English Language and Usage Stack Exchange](http://english.stackexchange.com/questions/tagged/grammar)
Answer: A quick search and I could not find any real life examples of countries ending in -ith which means there is likely no specific rule defined for that scenario.  However I did find this article which goes quite in depth on the topic, and should be a good guide on how to approach it.  Here is its final summary:

After seeing the distribution of the suffixes of nationality on a world map, and studying the origins of these suffixes, I think we should be reasonably convinced that the choice of suffix is not entirely a matter of chance or taste. Instead, there are historical and linguistic factors which determine why one suffix is used for a certain nationality but another suffix for a second one.

What do they identify themselves as?
From a world building perspective, grammar rules tend to take a back seat to how people identify themselves as and how external groups identify them as.  Their history provides a huge factor in this (as AlexP demonstrates).  For real life example look at the United Kingdom.  People there have a wide variety of ways they identify themselves as (British, Scottish, Welsh and many more).  People in the United States of America identify themselves as Americans, but back early in its history it was common for them to identify themselves by their state (for example Virginian).  Also, someone in Brazil could call themselves American since Brazil is in South America.
Needless to say the decision is up to your people to make, and they might have differing opinions on the subject even in their own kingdom.  So people in the nothern part may call themselves Bonfrithians, while those in the south call themselves Bonfrisians because they have an awful tendency to replace th sounds with s.
Answer: Options: Bonfrithians -- Bonfrithans -- Bonfrithish -- Bonfrithi -- Bonfrithee -- Carniolans (because the kingdom used to be the province of Carniola before the successful uprising centered around the city of Bonfrith) -- Frithish, Frithians, Frithans or Frithi (because Bonfrith means "goodness of Frithans" in Frithish, or because the Frithi nation is divided between the rival kindoms of Bonfrith and Malfrith).
Answer: You can choose. There are almost no rules in that regard. We call people from Britain Britons, people from Brittany Bretons, people from France French(men) and people from Italy Italians. You can even invent new suffixes based on their languages or history. Also, what is Bonfrith? A nation? A people? Does Frithia exist? Base your decision on that.
eg. In my world I have the Dimofragrian Kingdom, also referred to as Dimofragria. But the people are Fragrians and the main language is Fragrian. Dimo only reffers to the ruling dynasty.
Answer: If people from Britain can be called the English and if people from the Ottoman Empire can be called the Turks, I'm pretty sure you're not constrained at all.  (Yes, the two examples might not be technically accurate - but I've definitely heard both in casual conversation.)
Answer: Bonfs? Bons? If they speak any Slavic family languages, i.e. Russian or Polsk, it will be Бонфрициане ( for many persons and Бонфрицианин for single person) for Russian language, and Bonfritsiane (or Bonfritsian in for single person) for Polsk. Maybe the shorter and more vulgar form will be Бонфрицы (Bonfritsy).
Answer: A firth is a narrow estuary, so really the kingdom is "The Narrow Estuary of Bon" (assuming the word is the same in this world).  Hence, the people would be probably be Bons.
That being said, the history here matters.  The Dutch live in the Netherlands, so people names don't always match up with country names (though they often do).  Really, it matters what Bon refers to, and why the Firth, and the country are named after it.  Was Bon a person, a tribe, some natural phenomenon?  And is the whole country based around the Firth?  Or was the Firth some initial territory that has since expanded or even been lost?  Regardless they'd probably be named Bons, unless Bon refers to some natural phenomenon (the Netherlands means "the lowlands", so referring to the inhabitants as Nethers ("lows") would be weird.
Edit: Whoops!  Misread the name.  Still, Bonfrith sounds kinda like a compound word, with Bon and Frith meaning different things, so I stand by Bons.
Comment: Bonfrith not Bonfirth..
Answer: Historically, it has often been the other way around: the land is named after the people. Hence the large number of countries whose names end in -land or -stan.
To answer your question,

... according to correct grammar?

English grammar, I assume. And the answer is that it could be almost anything, as English is happy to adopt words from other languages, and demonyms are often highly irregular. If you are deriving the name of the people from the place (as does happen, sometimes), Bonfithian seems right. But compare Mancunian (Manchester), Liverpudlian (Liverpool), Londoner (London), Hollander (North Holland & South Holland), Glaswegian (Glasgow), Galwegian (Galway), Corkonian (Cork), Rohirrim (Rohan) to see some of the variability out there. If you develop a conlang, you could derive the English word from that of the conlang.
Basically, the choice is up to you. You should consider the history of the kingdom, and think about where the name comes from. If the land is named after the people, then the people should have the shorter name; if the people are named after the land, then the name of the people will be longer: probably the land name followed by a suffix. Or the two names could be completely unrelated: consider the Dutch living in The Netherlands.


What's the advantage of 3-level laser over 4-level laser?

Question: Since it is way easier for a 4-level laser to get population inversion than 3-level laser, 3-level laser is still in use nowadays. So what's the advantage of 3-level laser over 4-level laser?
Answer: I guess you should take the view of an experimental physicist:

Which atoms are available and where are their energy levels?
How can I excite the atoms in order to get inversion?
What are the properties which I need my laser to fulfill (e.g. line width, power, ...)?
How complicated and stable is the set-up? How much does it cost and how long will it take to get the laser running?
Comment: +1 for first point. There are quite a few of the lanthanide ions (Er, Ho, Tm) working in three-level scheme. Of course 4-level would be better, but 3-level is what we have for these ions. And this is technology, so "good enough" is all we need.


Are there any up to date walk though videos on how to use Tellor for fetching data feeds? or use how to use Tellor in general?

Question: Most of the videos on YouTube are out of date and the code doesn't match with what is on GitHub, making it really frustrating to follow along and learn how to use Tellor. The project is really cool but as a newbie trying to figure out how to actually use the protocol is kind of difficult. The resources online are limited or out of date across the board. I assume their documents and code are constantly being updated, which is great, but for the average developer trying to get use to working with this oracle, it makes it very hard to stay motivated and continue to use this them or follow along with the videos online. At the very least I would love for the 'sample using Tellor' or the 'playground' code to be in sync with the videos online.
Comment: Well, you found a good opportunity, create the videos yourself. Even the project may encourage you to do the videos.
Answer: Ask and you shall receive! Thanks for bringing this to our attention!
See video for updated Sample Using Tellor exercise:
https://youtu.be/GUTVhtffQQs


How can I convert the current from a fan to the microphone headset input on an iphone?

Question: I am working on creating an anemometer (or wind meter) for the iPhone.  I am a programmer and know exactly how I could do this on the software side of things, but I am a complete noob when it comes to electronics.  I have seen many other posts about putting voltage or an audio line to the microphone, but I'm trying to convert the current generated by a small spinning fan into a microphone input that I can measure on the iPhone.  How can I make sure that the volts generated by the fan will appropriately scale to the input of the iPhone microphone?
Answer: Instead of trying to input analog levels, you may have more luck if you use your input to control the frequency of an audio oscillator.  You would then measure the frequency in software on the phone.
But you might not even need to do that - if not equipped with filter capacitors, your generator already may have an audio-frequency variation proportionate to speed in its output due to the poles and brushes.  If you had a brushless device which output A/C, this would work even better, but you might be able to do something by A/C coupling the output of your current device with a series capacitor chosen to pass only the brush noise.
You may also want to think about a protection circuit for the phone, such as some back to back diodes.
Answer: "Best":  The "best" solution is to use a low cost microcontroller to measure the data and to output a signal that is suited to what the iPhone can handle. This could eg be a tone sequence or frequency or about anything else measureable. All up parts cost could be under $1. This takes some microcontroller hardware experience - but may be an acceptable approach.
"Simpler": As long as extra hardware is acceptable, a reasonably level independent way is to convert voltage to frequency and then to measure the frequency in software. If in-device measurement is too hard the sound could eg be saved to a file, sent to a remote point, measured and returned. Or it could be relayed live. But hopefully you have enough access to processing power to do it directly. The frequency can be as low or high as you wish - and if you can measure time periods you could gate the tone on and off for a period related to voltage. Achievable reolution may not be large but it should be able to meet the ned. Averaging over many samples would be possible.

DIY with an LM555 - cheap and may be good enough.
EDN - NE555 timer sparks low-cost voltage-to-frequency converter
Related circuit from here shown below. Opamp can be common and low cost LM358 or LM324 BUT a virtual ground at about half supply would be needed as opamp output must swing negative relative to ground to operate integrator. Supply voltage can be 5V or more with LM358 or LM324.

LM331 dedicated precision voltage to frequency converter
Analog Devices MT028 - V-to-F tutorial - 7 pages. Good and has links.
AD VtoF IC selection guide
Linear technology AN14 Designing high performance V to F converters - overkill for what you want but gives ideas.
Microchip says ...
Many many idea starters and some complete circuits
Comment: What is it that corresponds to loudness?  Is it frequency?  On the iphone, it is really easy in software to measure relative loudness.  Will voltage to frequency help me to accomplish this?


Writing a simple equation parser

Question: What sorts of algorithms would be used to do this (as in, this is a string, and I want to find the answer):
((5 + (3 + (7 * 2))) - (8 * 9)) / 72

Say someone wrote that in, how could I deal with so many nested parenthesis?
Comment: See my SO answer on how to write top down recursive descent parsers. This method is very easy for expressions.
Comment: This is an expression not an equation. http://www.mathnstuff.com/math/algebra/aequex.htm or https://en.m.wikipedia.org/wiki/Equation
Answer: You can use Shunting yard algorithm or Reverse Polish Notation, both of them are using stacks to handle this, wiki said it better than me.
From wiki,
While there are tokens to be read:

    Read a token.
    If the token is a number, then add it to the output queue.
    If the token is a function token, then push it onto the stack.
    If the token is a function argument separator (e.g., a comma):

        Until the token at the top of the stack is a left parenthesis, pop operators off the stack onto the output queue. If no left parentheses are encountered, either the separator was misplaced or parentheses were mismatched.

    If the token is an operator, o1, then:

        while there is an operator token, o2, at the top of the stack, and

                either o1 is left-associative and its precedence is less than or equal to that of o2,
                or o1 is right-associative and its precedence is less than that of o2,

            pop o2 off the stack, onto the output queue;

        push o1 onto the stack.

    If the token is a left parenthesis, then push it onto the stack.
    If the token is a right parenthesis:

        Until the token at the top of the stack is a left parenthesis, pop operators off the stack onto the output queue.
        Pop the left parenthesis from the stack, but not onto the output queue.
        If the token at the top of the stack is a function token, pop it onto the output queue.
        If the stack runs out without finding a left parenthesis, then there are mismatched parentheses.

When there are no more tokens to read:

    While there are still operator tokens in the stack:

        If the operator token on the top of the stack is a parenthesis, then there are mismatched parentheses.
        Pop the operator onto the output queue.

Exit.

Comment: this may helpful http://social.msdn.microsoft.com/Forums/en-US/csharplanguage/thread/31ac96da-415e-424b-9e1f-6aec86c4c3ae
Answer: The easiest way to solve this is to implement the Shunting Yard algorithm to convert the expression from infix notation to postfix notation.
It's Easy-with-a-capital-E to evaluate a postfix expression.
The Shunting Yard algorithm can be implemented in under 30 lines of code.  You'll also need to tokenize the input (convert the character string into a sequence of operands, operators, and punctuators), but writing a simple state machine to do that is straightforward.
Answer: James has provided a good answer.  Wikipedia has a good article on this as well.
If (and I don't recommend this) you wanted to parse that expression directly, given that it seems orderly in that every set of parens has no more than one pair of operands, I think you could approach it like this:
parse to the first ")".  Then parse back to the previous "(".  Evaluate what's inside and replace the whole set with a value.  Then repeat recursively until you are done.
So in this example, you would first parse "(7 * 2)" and replace it with 14.
Then you would get (3 + 14) and replace it with 17.
And so on.
You can do that with Regex or even .IndexOf and .Substring.
I'm going without benefit of checking my syntax here, but something like this:
int y = string.IndexOf(")");
int x = string.Substring(0,y).LastIndexOf("(");
string z = string.Substring(x+1,y-x-1) // This should result in "7 * 2"

You'll need to evaluate the resulting expression and loop this until the parens are exhausted and then evaluate that last part of the string.
Comment: So, if you liked James's answer, why didn't you upvote it? ;-)
Comment: Because I just started contributing yesterday and don't have the required 15 rep yet or I would have.  You could help with that of course :)
Answer: You could use either a state machine parser (yacc LALR, etc.), or a recursive descent parser.
The parser could emit RPN tokens to evaluate or compile later.  Or, in an immediate interpreter implementation, a recursive descent parser could calculate subexpressions on the fly as it returns from the leaf tokens, and end up with the result.
Answer: I would use the tools that are available nearly everywhere.
I like lex/yacc because I know them but there are equivalents everywhere. So before you write complex code see if there are tools that can help you to make it simple (problems like this have been solved before so don;t re-invent the wheel).
So, using lex(flex)/yacc(bison) I would do:
e.l
%option noyywrap

Number      [0-9]+
WhiteSpace  [ \t\v\r]+
NewLine     \n
%{
#include <stdio.h>
%}

%%

\(              return '(';
\)              return ')';
\+              return '+';
\-              return '-';
\*              return '*';
\/              return '/';

{Number}        return 'N';
{NewLine}       return '\n';
{WhiteSpace}    /* Ignore */

.               fprintf(stdout,"Error\n");exit(1);

%%

e.y
%{
#include <stdio.h>
    typedef double (*Operator)(double,double);
    double mulOp(double l,double r)  {return l*r;}
    double divOp(double l,double r)  {return l/r;}
    double addOp(double l,double r)  {return l+r;}
    double subOp(double l,double r)  {return l-r;}
extern char* yytext;
extern void yyerror(char const * msg);
%}

%union
{
    Operator        op;
    double          value;
}

%type   <op>        MultOp AddOp
%type   <value>     Expression MultExpr AddExpr BraceExpr

%%

Value:          Expression '\n'   { fprintf(stdout, "Result: %le\n", $1);return 0; }

Expression:     AddExpr                          { $$ = $1;}

AddExpr:        MultExpr                         { $$ = $1;}
            |   AddExpr   AddOp  MultExpr        { $$ = ($2)($1, $3);}

MultExpr:       BraceExpr                        { $$ = $1;}
            |   MultExpr  MultOp BraceExpr       { $$ = ($2)($1, $3);}

BraceExpr:      '(' Expression ')'               { $$ = $2;}
            |   'N'                              { sscanf(yytext,"%le", &$$);}

MultOp:         '*'                              { $$ = &mulOp;}
            |   '/'                              { $$ = &divOp;}
AddOp:          '+'                              { $$ = &addOp;}
            |   '-'                              { $$ = &subOp;}
%%

void yyerror(char const * msg)
{
    fprintf(stdout,"Error: %s", msg);
}

int main()
{
    yyparse();
}

Build
> flex e.l
> bison e.y
> gcc *.c
> ./a.out
((5 + (3 + (7 * 2))) - (8 * 9)) / 72
Result: -6.944444e-01
>

The above also handles normal operator precedence rules:
Not because of anything I did,but somebody smart worked this out ages ago and now you can get the grammar rules for expression parsing easily (Just google C Grammer and rip the bit  you need out).
> ./a.out
2 + 3 * 4
Result: 1.400000e+01

Answer: First convert the expression into prefix or postfix form. Then its very easy to evaluate!
Example:
Postfix expression evaluation.
Answer: If the expressions are known to be fully-parenthesized (that is, all possible parentheses are there), then this can easily be done using recursive-descent parsing.  Essentially, each expression is either of the form
 number

or of the form
 (expression operator expression)

These two cases can be distinguished by their first token, and so a simple recursive descent suffices.  I've actually seen this exact problem given out as a way of testing recursive thinking in introductory programming classes.
If you don't necessarily have this guarantee, then some form of precedence parsing might be a good idea.  Many of the other answers to this question discuss various flavors of algorithms for doing this.
Answer: What?  Nooooo.  Unless this is a homework assignment, do not write a parser.  There are a hundred parsers out there and they all have one advantage over all the suggestions here: they're already out there.  You don't have to write them.
Answer: Yes the algorithm is Shunting yard algorithm but if you want to implement I suggest you python and it's compiler package
import compiler
equation = "((5 + (3 + (7 * 2))) - (8 * 9)) / 72"
parsed = compiler.parse( equation )

print parsed

You can also evaluate this expression with built-in eval() method
print eval("5 + (4./3) * 9") // 17

Answer: Or you can just do this in one line in R:
> eval(parse(text = '((5 + (3 + (7*2))) - (8 * 9))/72' ))
[1] -0.6944444

Writing a simple equation parser


Are thru-axles generally hollow or solid?

Question: Need to know if these thru axles (of any size) have an internal diameter or are completely solid. How common is each type?
Comment: If you are refering to thru axles that are standard on MTB and Road Disk bikes, they are hollow.
Answer: Thru Axles are a standard for wheel fasteners that was introduced fairly recently for MTB and later for road bikes. Today thru axles come typically in 15 mm or 12 mm diametres.
If you mean thse, they are indeed always hollow. Any solid bolt with such a large diametre would be excessively heavy. Even when using light magnesium alloys.
The whole innovation of thru axles revolves around that when having a structural element of sufficient size one may do without its core. In other words, a tube of a large radius is under many loads stronger than a slimmer rod of the same mass and material. In the case of a hub axle one can rule out loads (e.g. shearing) where a rod would be stronger.
Comment: "a tube of a large radius is under many loads stronger than a slimmer rod of the same mass and material" hence the fat-tube early-generation aluminium bike frames.


What's the meaning of "she is a real pip"?

Question: I heard this expression  in the TV series Better Call Saul. A character spoke to a secretary, and  he seemed annoyed.
After he spoke to her chief and said "your secretary is a real pip".
What that could mean? I imagined something negative, but I don't know.
The dictionary does not report a clear explanation of the meaning referred to a person...
Pip
Comment: Here's [another Oxford definition](https://en.oxforddictionaries.com/definition/us/pip), but I'm not sure why I got that version as I'm in the UK.
Comment: Do you know what season and episode and what time in the episode?
Comment: ...... Which movie?
Comment: Better call Saul, it's a TV series
Comment: It sounds almost the same as "she's a real brick".
Comment: @ArmthegoodguysinAmerica: S03E02, "Witness", ~19:40.
Answer: It's originally American English.

colloquial (originally and chiefly U.S.). Something remarkably good; an excellent or very attractive person or thing.

(Oxford English Dictionary)

informal An excellent or very attractive person or thing.

(Oxford)

Slang, Obsolete
  a person or thing much admired

(Webster's New World College Dictionary, 4th Edition. Copyright © 2010), quoted at Collins)
In the show, it could have been used sarcastically, like any other positive descriptor.
Answer: Jonathon Green, Chambers Dictionary of Slang (2008) offers a series of meanings for pip as U.S. slang, and conveniently includes approximate dates of first known occurrence for each meaning:

pip n. {abbr[eviation of] PIPPIN n. ["|mid-17C+| (also pipkin, pippins) a term of approval or congratulation, applied to a person; thus affectionate term of address my pippin"]} 1 |late 19C+| (orig. US) the very best, the finest example. 2 |1900s| (US) a negative, bad example. 3 |1920s–30s| (US) an innocent. 4 |1950s| an attractive woman.

The example that the poster asks about clearly uses pip in the sense of Green's definition 4.

Early instances of 'pip' used in the relevant sense
Although Green states that pip in the relevant sense originated as US slang, he also says that its lineage goes back to the 1600s (and presumably to Great Britain), as pippin.
Green seems to have misgauged the earliest instance of pip in the specific sense of "an attractive woman" by several decades. From Rex Beach, The Barrier, serialized in the Santa Cruz [California] Evening News (March 16, 1909):

"Those your kids, too, eh?" Stark continued.
"Yes, and I got another one besides—older, a girl." "She's a 'pip,' too," said "No Creek" Lee fervently. "She's plumb beautiful."

From "'Dealin' Out Jobs' Is Organization's Business, Says Ward Heeler in 'The Crack in the Bell'," in the Philadelphia [Pennsylvania] Ledger (May 13, 1918):

"I very much hope that I may meet you again," he declared with fervor, eyes still clinging to the figure of the girl.
"Oh, I hope so," echoed Sylvy, sincerely enough, though not very confidently.
"Ain't she a pip?" demanded Kelly, advancing from the background in which he had temporarily obscured himself.

From "Loud and Clear: Karl Nakagawa," in the [San Francisco, California] Shin Sekai (June 5, 1931):

Like all good boys, he has his weakness. Looks like an interracial romance is in bloom. The writer met his weakness recently and she's a pip. One would wonder how such a lovely creature could ever forsake men of her own race. Her form, her pearly white skin, her eyes—what an example of beauty! Makes one's heart go pitter-pat.

And in an episode of the nationally serialized daily newspaper comic strip Alley Oop in the Borger [Texas] Daily Herald (September 4, 1938) a character named Foozy says this:

Say—who's th' doll with Oola there? She's a pip! My gosh, what gorgeous hair!

Not surprisingly, there are instances from the same period in which speakers use longer forms of pip with the same evident meaning. From Stuart Stone, "Matched by Mail," in the Tacoma [Washington] Times (September 3, 1910):

"Oh, Tex—she'll do. She's a pippinoola—that Miss Nellie. Take me in and introduce me as her true lovin' heart."

From Joseph Kescel, "The Mirage," in the El Paso Times (April 6, 1917):

"Who was that I saw you with a few moments ago?" asked the "Mirage."
"The young lady I wrote to you about, staying over at the Thompsons'. She's the best that has come this way in a long time. Sure, you're going to meet her. You'll have to speak loudly to her—hearing's not very good. Too bad too for she's a pippin."

It bears noting in connection with pippin that the word has been applied to "a crisp tart apple having usu. yellow or greenish-yellow skin strongly flushed with red and used esp. for cooking" since the fifteenth century, according to Merriam-Webster's Eleventh Collegiate Dictionary (2003). The Eleventh Collegiate considers the later meaning of pippin—"a highly admired or or very admirable person or thing"—to have emerged from the original apple meaning.
Answer: Both these choices are correct. PIP references the Dickens character Philip Pirrup from "Great Expections" who underestimates others, overestimates himself, gets up to a lot of trouble but is still well liked by most. SPOT ON! I am in my seventies and remember my father's folks (from Yorkshire, England) using this expression and sometimes at me. Our daughter who loving sometimes refers to her DUB (Dublin, Ireland) husband Philip Price as Pip! QED
Comment: Please add a citation with the meanings you specify.
Comment: The chances of a Dickens reference appearing in "Call Saul" (an American series about a roguish but likeable lawyer in modern day America) are so exceedingly small that you would have to go some distance to show that connection.
Answer: Could it be from Dickens' "Great Expectations"?  The character, Pip (short for Philip Pirrip), demonstrates the qualities which would make someone "a pip".
He underestimates others, overestimates himself, gets up to a lot of trouble but is still well liked by most.
Comment: This answer will need something more than a guess to be taken seriously.. Can you back it up in some way?


How to measure the contribution of each input channel to a network's accuracy?

Question: As the title says, let's assume we have some neural network. More specifically, a regression network in case that changes anything. It takes multiple 2D input channels. How could one measure how much each input channel is contributing to the accuracy of the network on a validation set, to know which channels to keep and which are not really necessary?
Answer: Neural networks are black boxes, and figuring out its internal workings can be really hard. When you decide to use ML for your model, you are sacrificing accuracy for interpretability.
However, that does not mean it is totally impossible to interpret networks.  The most tedious way to determine feature importance would be to remove features and see how it impacts the model. If you're interested in research into the subject, I've encountered some research papers to use decision trees to understand networks.
https://openaccess.thecvf.com/content_CVPR_2019/papers/Zhang_Interpreting_CNNs_via_Decision_Trees_CVPR_2019_paper.pdf
https://arxiv.org/pdf/1802.02195.pdf
Answer: After searching for multiple options, I'd recomment using Captum. Implements multiple NN analysis papers to run on any pytorch model:
https://captum.ai/
So it can easily calculate the imporance of features for the ouptut, a specific layer or even a specific neuron.


Is it possible to make xelatex to compile just once?

Question: I want and need to run all the incantation steps like bibtex and extra compilations only at the end of the day.
It can be useful to say that I am using TexLive for Kile/Debian, just in case there is only a specific solution.
Comment: If you want information about the last section to appear in a table of contents at the start then it necessarily requires multiple passes over the document.
Comment: It isn't clear at all xelatex only compiles twice if you run it twice, if you only do it once (which should be the normal case while working on a document) it will only compile your document once. What is the question?
Comment: Ok, I realised the problem is with Kile, I will post an answer.
Answer: Kile enables by default the option "Automatically run additional tools." at Settings -> build tools -> xelatex.


How can I replace all blocks of one type with a different type of block, within a certain region?

Question: I'd like to be able to select a region, either with an outside graphical utility or command line, or with native Minecraft commands, and be able to replace all blocks of one block type with another type, e.g. change all cobblestone in the region to stone. Does a program/mod exist that can do this? What about commands?
Answer: As of 1.8, this can be done in vanilla with the /fill command. It can be done using command blocks or typing it straight into the chat.
For example, to change cobblestone to stone:
1.8 to 1.12:
/fill <x1> <y1> <z1> <x2> <y2> <z2> stone 0 replace cobblestone

1.13+:
/fill <x1> <y1> <z1> <x2> <y2> <z2> stone replace cobblestone

Change <x1> <y1> <z1> to the coordinates of one corner of the rectangular area, and <x2> <y2> <z2> with the coordinates of the opposite corner.
Answer: WorldEdit has such a command after selecting the area type

//replace [old block] [new block]

This will turn all of the first block from the area into the second block.
Comment: As the question refer to "Within a region" and i interpret it as a MCRegion aka a chunk, I would add on to the question the command `/chunk` which selects the chunks that your region encompasses.
Answer: In 1.13. The /fill command has been updated, this is the new syntax:
/fill <from> <to> <block> [replace|destroy|hollow|outline|keep]

from and to define two opposite corners of the volume that you want to fill
block is the block that you want to fill into that volume
The next keyword decides what exactly should happen in the specified volume, it is optional and not using it defaults to replace.
replace sets every block in the specified volume to the specified <block>.
destroy works like replace, but every block in the specified volume will drop whatever item they would usually drop (diamond ore drops diamonds and experience for example) and there will be a breaking particle effect.
hollow works like replace, but the volume will then be hollow, there will be a one block thick wall and everything inside will be set to air.
outline works like hollow, but only the one block thick wall will be placed, everything inside will stay the way it is instead of being set to air.
keep works like replace, but only air blocks get filled with the specified block.
You can also use this syntax instead:
/fill <from> <to> <block> replace <filter>

In this case only blocks specified by the <filter> will be set to the block specified in <block>
So to replace all cobblestone in a volume between the coordinates 60 60 60 and 70 70 70 with stone you can use this command:
/fill 60 60 60 70 70 70 stone replace cobblestone

Answer: MCEdit has this capability.  As an example, I made a selection that included grass blocks, and replaced the grass in that selection with cobblestone:

The tool that's selected in the first image is the find tool. Once open, there's an option to change it to find and replace.  Then it's just as easy as selecting your two block types and hitting replace.


Getting back Windows 10 recovery which has windows 7 recovery

Question: Initially I used regback registry to fix USBPCap USB not working problem . After sometime It gave 0xc000021a BSOD  . So i used Windows 10 iso to repair and messed it up with bootrec and bcdedit commands.
Now Windows 10 iso opens Windows 7 recovery options.
Tried SFC and dism.
I am able to boot PC only by disabling driver signature enforcement . Which I can select only from 0x0000001 error  after multiple restarts from BSOD.
Debugging minidump showed ntoskrnl to be causing 0xc000021a error. Reset and restore not an option
Incidents may not be related
Also startup repair using windows 10 iso which shows Windows 7 logo and UI gives OS mismatch error.
Comment: Not answer to your question, but wouldn't it be easier to just back up your stuff and do clean reinstall? Fixing windows is usually pain in the ass.
Comment: No I want all my data and software. I am a software geek of sort. So I need all my customizations. And currently I don't have any HDD with me. But I have lot of data. Cloud is off options. Because in India ,Internet Charge of backing up all my data = 5 times the price of my whole PC. Thanks call help.
Comment: Got recovery back to normal by setting boot mode to UEFI in BIOS.
Still couldn't fix 0xc000021a though.
Answer: Got recovery back to normal by setting boot mode to UEFI in BIOS.


Does this sentence example of perpetual lamentations make sense?

Question:
The foreigners mourned with perpetual lamentations for 3 months following Murray's death.
Answer: Previous answers seem to focus on the literal meaning of "perpetual". But the Oxford dictionary gives this secondary definition:

Occurring repeatedly; so frequent as to seem endless and uninterrupted.

I would say then that your sentence is quite acceptable. As a native British English speaker I can confirm that "perpetual" is used in a looser, hyperbolic way to mean either frequent or persistent, for example:

Stop your perpetual whining

A "perpetual whiner" is quite a common insult (Google it!) and obviously does not mean that someone complains 24 hours a day every day without letup. It just means that they frequently complain.
Likewise, your sentence does not literally mean that their lamenting is expected to go on forever, just that it is so frequent and persistent so as to seem that way.
Answer: It does not make sense, as perpetual means "without end, forever" and 3 months is a limited time frame.  Perpetual is a stronger word than even "endless", which is a word that would work in this sentence.  "Endless lamentations for 3 months..." would imply that they didn't stop their lamentations during these 3 months, but did stop after the 3 months.  Perpetual is a word that is exclusively used for things that NEVER end.
Comment: *Endless* wouldn't work either. It, too, means *without end*. It's no different than *perpetual*. The only words that work here are *continuous* and *continual*, depending on if there were interruptions or not. Assuming you want to interpret *endless* and *perpetual* in a literal sense. If you don't interpret *endless* literally, you don't need to interpret *perpetual* literally either.
Comment: *Endless* literally means without end, but colloquially can be used in a more limited manner.  It's implied that it's endless within a certain limit.  Perpetual, on the other hand, is typically used in a manner that expressly disallows setting boundaries around it.  Think about "Perpetuities" in contracts, which are clauses that are contractually required to be included in FUTURE contracts as well, making them never end even when you'd think it would end.
Comment: *Perpetual* can also be used colloquially. Perpetual motion machines and perpetual flames are not *really* perpetual. And contracts are frequently broken. Just like many marriages seldom actually end in parting in death.
Answer: As pointed by my namesake, Richard, perpetual is not the right word to be used in your phrase.
According to the Cambridge Dictionary
perpetual

continuing forever, or happening all the time

forever

for all time

For all time, during an unlimited time, not just for 3 months. Maybe the word that you are looking for is uninterruptedly
uninterruptedly

in a way that is without any pauses or interruptions

The foreigners mourned uninterruptedly for 3 months following Murray's death


What is a secure way for storing AWS IAM credentials?

Question: When creating a new user in AWS IAM, it generates access keys for that user. Where is a secure and readily accessible location to store these credentials?
Comment: We need more information about those users. Those IAM users are managed by real users or 3rd party users? are integrated into some automatic processes, CD pipelines...?
Answer: Well there are a lot of places to keep them secure

you can use something like hashicorp vault to keep those kind of secrets
you can use something like lastpass and my personal favorite is enpass

But first you need to define your needs so you can choose the right tool to use and integrate with your daily use
Answer: Keepas can be another option where you can store your secret keys/passwords .
Here is the document document for your reference : https://aws.amazon.com/marketplace/pp/prodview-wr72ujcv4dhmo
Answer: In case you can provision the IAM accounts programmatically, for example using Terraform, you could ask users for their PGP public keys (or fetch them from company's PGP server) and encrypt their credentials immediately upon provisioning with PGP.
You can then safely distribute the encrypted credentials to the user, however you see fit, store them in Keepass/1password/other password manager where you can share them with the users, or just leave the encrypted credentials in CI pipeline and send them via encrypted private messenger without compromising security.


Put numbers to equations

Question: I want that latex always puts a number behind an equation that I created with $$ $$, but not when I did it with $ $. Is this possible?
Comment: Use `\begin{equation} ... \end{equation}` instead of the outdated `$$ ... $$` and LaTeX will do just what you want. See http://tex.stackexchange.com/questions/503/why-is-preferable-to and http://tex.stackexchange.com/questions/98397/enumerate-formulas/98401#98401
Comment: Note that `$ ... $` creates inline rather than displaystyle formulas. You'll therefore never get a numbered, display-style equation anyway if you use `$ ... $`. For more information on how to create unnumbered and numbered displaystyle equations, see the answers to the posting [What are the differences between $$, \[, align, equation and displaymath?](http://tex.stackexchange.com/q/40492/5001)
Comment: Welcome to TeX.SX! You can have a look at [our starter guide](http://meta.tex.stackexchange.com/q/1436) to familiarize yourself further with our format.
Comment: I see you deleted your other question. I was about to post an answer that you may find interesting, but can't do it since one can't post answers to deleted postings. If you want, send me an email at "firstname.lastname@example.com" and I'll write back with the answer. I will delete this comment in a little while.
Answer: You should not use $$ $$ with LaTeX: it's a plainTeX command, and you have incorrect vertical spacings; it's replaced with \[ \]. If you want numbers with displayed equations, use \begin{equation} \end{equation} for just one equation, and, from the amsmath package, \begin{gather} \end{gather} for a group of centred displayed equations.
If you want several equations with one alignment point, use \begin{align} \end{align},  also from amsmath. You'll find the description of other equation environments in the ams documentation (alignat, flalign, multline, &c.).
Between successive equations in all these environments, you can put some text with the \intertext command, or the \shortintertext command from the mathtools package if you find vertical spacing for these short pieces of text is too big.
Incidentally, if you load mathtools, you don't have to load amsmath since it loads and extends amsmath.
Comment: The `gather`environment is also from `amsmath`.
Comment: It was implicit. I add that to my answer.

Put numbers to equations