Solve $|x - z_1| = d_1 + y$ and $|x - z_2| = d_2 + y$ simultaneously for $x$ and $y$

Question: Given the two equations $|x - z_1| = d_1 + y$ and $|x - z_2| = d_2 + y$ , and suppose that $z_1, z_2 \in \mathbb{R}$, $z_1 \neq z_2$ and  $d_1, d_2, \in \mathbb{R}_{> 0}$ are all known reals, solve this system of equations simultaneously for $x \in \mathbb{R}$ and $y \in \mathbb{R}_{\geq 0}$.
First of all, I know that there aren't always solutions. If you take $z_1 = 8$, $z_2 = 11$, $d_1 = 6$ and $d_2 = 1$, it's impossible to find $x$ and $y$ that satify these equations. If you look at the possible value of $x$, by the first equation you get $x = 14 + y$ or $x = 2 - y$. Because we know that $y > 0$, the larger possible solution is $x = 14 + y$. With the same reasoning, we get that the larger solution of the second equation is $x = 12 + y$. There is no $x, y$ that satisfy both equations at once. The same reason applies if you look at the smaller of the two, so $x = 2- y$ and  $x = 10 - y$.
Now suppose that there is a solution, how do we find it? Breaking $\mathbb{R}$ up into regions and checking each case where the absolute value changes the sign of the inside expression, is not the way I want to solve this. I want to get general expressions for $x$ and $y$, if that's possible.
I can solve this if $y = 0$ (which I don't know initially, but that's not the point). I square both equations and subract them, so I get a linear equation for $x$, which is easily solved. But I can't use the same trick if $y > 0$. I get the equations
$$
x^2 - 2\cdot x\cdot z_1 + z_1^2 = d_1^2 + 2\cdot y\cdot d_1 + y^2
$$
and
$$
x^2 - 2\cdot x\cdot z_2 + z_2^2 = d_2^2 + 2\cdot y\cdot d_2 + y^2.
$$
I can subtract these, so I get rid of $x^2$ and $y^2$. But then there remains an equation wich has both $x$ and $y$:
$$
x\cdot 2(z_2 - z_1) + z_1^2 -z_2^2 = d_1^2 - d_2^2 + y\cdot 2(d_1 -d_2).
$$
At this point, I thought about getting rid of $y$ by subtracting the equations, resulting in
$$
|x - z_1| - |x-z_2| = d_1 - d_2.
$$
If I bring the $|x-z_2|$ to the RHS and squaring this, I get
$$
x^2 - 2\cdot x\cdot z_1 + z_1^2 = (d_1-d_2)^2 + 2\cdot (d_1 - d_2)\cdot |x-z_2| + (x^2 - 2\cdot x\cdot z_2 + z_2^2).
$$
Now I write this as an equations for $|x-z_2|$:
$$
|x-z_2| = \frac{- 2\cdot x\cdot z_1 + z_1^2 - (d_1-d_2)^2 +2\cdot x\cdot z_2 - z_2^2}{2(d_1-d_2)}.
$$
It's technically possible to square this equations, resulting in an quadratic expression for $x$. This however, looks very, very unappealing. Another problem is that if I solve this expression, I still don't know an exact value of $x$, because of the $\pm$ in the quadratic formula (I've checked using a problem with known numbers that the root isn't (always) $0$, unfortunately).
So, I'm stuck. I've used all the tricks I known regarding the absolute value, but it doesn't seem to help. I'm now wondering if it is at all possible to get an expression for $x$ and $y$, even if there is a solution.
Answer: There are no solutions when $|z_1-z_2|<|d_1-d_2|$, one solution when $|z_1-z_2|>|d_1-d_2|$, and a whole region of solutions when $|z_1-z_2|=|d_1-d_2|$. For the one-solution case, taking $z_2>z_1$, the solution is at $x=(z_1+z_2+d_2-d_1)/2, y=(d_2+d_1+z_2-z_1)/2$.
The argument is pretty much from the geometry of the graphs of these functions.
Comment: If I take $z_1 = 4, z_2 = 20, d_1 = 3, d_2 = 11$, the solution is $x = 8$ and $y = 1$. However, if I use your equations, I get $x = 16$ and $y = 15$. Where is my mistake? Edit: ah, I switched some variables.
Comment: Could you explain to me how you got this solution if $z_2 > z_1$?


Why are all of my dropdown menus a blank black screen?

Question: I recently updated my ubuntu 16.04 system and now all the drop down menus are black. It starts up fine and looks normal until i open an app or click on a menu. I can not read or click anything in the menu. The only desktop environment I can get to work is Xfce. It works fine. Even the windows in the Ubuntu desktop environment have black squares around them and will not allow me the select them or move them around the desktop. Anyone ever experience this??
Answer: I think this is related to graphics drivers.
Today I had the same problem and I fixed it like this:
sudo apt-get upgrade

If you have any graphical errors it shows the packages you have to install or upgrade.
I saw errors about
libllvm3.8 libllvm3.8:i386 libmirclient-dev libmircommon-dev libmircookie-dev libmircookie2 libprotobuf-dev libxkbcommon-dev

so I fixed it by installing those packages
sudo apt-get install libllvm3.8 libllvm3.8:i386 libmirclient-dev libmircommon-dev libmircookie-dev libmircookie2 libprotobuf-dev libxkbcommon-dev

Answer: It's a well-known and longstanding bug in Linux >4.2, and specifically 4.3 and 4.4. See here:
https://bbs.archlinux.org/viewtopic.php?id=209065
I just got it in 14.04 again and restarting rather than shutting laptop should make it not happen... or downgrade or upgrade your kernel :(


In an agile project how should PM try to find risks upfront and if yes how?

Question: Usually in an agile process such as scrum we don't do an initial analysis as in waterfall model. How to identify project risk in agile process.
Answer: Just because the software is being developed using Agile doesn't mean there can't be a parallel project management effort - which will likely spam several sprints.
Answer: No matter what development methodology you are using there are a number of risks that can be known up front.  These need to be identified and mitigated.  During the project it is likely additional risks will be identified.
Many of the risks are fairly standard, and have known solutions.  Identifying them and putting mitigating practices in places is important.  Here a list of some of the risks you may want to consider.

Web design has a number of risks including SQL injection, insecure logins, cross-site scripting and others. See SANS: CWD/SANS TOP 25 Most Dangerous Software Errors for some examples.
Cyber security risks, see SANS: The Top Cyber Security Risks and SANS: Top 20 Internet Security Problems for some details.
Failure to adequately secure payment data. Compliance with Payment Card Industry Data Security Standard is a starting point.

There are additional project specific risk which need to be dealt with on a per project basis.  These include:

Technical risk in implementing new functionality.
Staffing/skills risk for the team.  The team may not have all the skills it needs.  You may have a limited number of team members with a critical skill.  Agile may make it easy to develop and/or transfer skills.
The risk of missed or unnecessary requirements.  Agile may help mitigate this risk.
Scope creap risk (additional out of scope requirements added during the project).  Agile may help accommodate/deal with the problem.
Answer: I disagree with the statement,that in SCRUM risk analysis is not done upfront
What about --
Risk analysis when a story is groomed & estimated during SPRINT plannnig --->
Considering & factoring in risks ( and considering mitigation - new stories ?? , "story is too big and risk -- break it down " , "no test to catch regression -- can not committ to this story unless regression tests are written " etc etc ) when story is groomed ?
Considering & factoring in risks when story points are being estimated ?
I do not think one is implementing SCRUM properly if formal risk analysis is not part of   the SPRINT planning process !
I would be very nervous as a PM,if risks are not analysed,discussed and mitigations proposed before committing a story to the board
Comment: I agree to certain extent that during sprint planning phase it is possible to do a complete risk analysis, but my thinking is it may be too late and as you suggested story point estimating may be a good time.
Answer: The problem isn't that risk management is not done upfront in Agile software development processes.  The problem is that risk management is not done explicitly, that is, risk management is implied in Agile processes so teams don't have the same notion of risk management as traditional project management expects.  This is not to say that explicit risk management and agile cannot work together.
The SEI's Continuous Risk Management paradigm fits very well with agile processes.  The best way I know to combine CRM with Agile is to perform a "mini" Software Risk Evaluation workshop using the SEI's risk taxonomy-based questionnaire as a guide.  Mini-SRE's take anywhere from a few hours to a day to complete and not only teach a team what they need to know to identify and manage risks but also creates the initial risk backlog necessary to move forward with other parts of Agile processes.  Such a workshop should happen during Sprint 0 and act as a guide for helping the customer decide which things to work on first, and other non-development things the team should be working on.

Explicit Risk Management in Agile Processes is an experience report from XP2008 on using Mini-SRE and CRM with Scrum
SEI's Risk Taxonomy-Based Questionnaire includes a set of questions and process for the software risk evaluation workshop (the whole process, not the mini version)
Answer: I agree Scrum doesn't explicitly talk about risk assessment as Waterfall does.
There are however a number of opportunities to handle risk within the scrum framework. Starting with the backlog refinement exercise. I like to use BDD for this part, and where areas are particularly complex use a 3 amigos format to understand the right approach.
This way most of the risks are identified prior to sprint planning. Even if risks are discovered during sprint planning or even during the sprint, Scrum allows for rethinking sprint goals and putting stories back on the backlog for more refinement.
Backlog refinement effectively houses the analysis and prioritisation work in a more iterative fashion that the upfront analysis that is seen in waterfall.
So you see, risk management and deep analysis is present but done on smaller chunks of work as other area of functionality are progressed.
This does lead to some "evolutionary" solution design as things can emerge that lead to changes in existing implementation so there is a trade off between momentum and analysis paralysis.
Depends on what you are building, but most people prefer momentum.
Answer: Due to the nature of agile methodologies, risks are not identified at the very start, as in the waterfall model, instead risk identification and mitigation take place throughout the process. As they are so incorporated in the ceremonies you undertake in agile, such as the daily scrum, risk analysis might not appear to you as taking place. This is of course what makes the agile method so much more adaptable than the waterfall method.
In terms of risks, there are risks which can be identified as general risks across any projects you undertake, while other risks are more specific to the project itself. It is the latter which are identified and reduced so well when using agile.
Answer: Brief Summary
"Agile" is a set of values and principles, not a framework. Therefore, I'll address myself specifically to the Scrum framework as a reasonable baseline, with the understanding that other agile frameworks often leverage Scrum or contain similar approaches that are at least comparable.
Project risk and risk management is not excluded from any agile methodology. There's just usually no explicit requirement for a separate risk register, or a mandate for risk-related items on the Product Backlog. That said, the principles and theory behind frameworks like Scrum make risk management an ongoing activity that is part of numerous events and artifacts, so you just need to reframe how you look at risk management in an agile context.
Scrum Leverages Emergent Design and Just-in-Time Planning for Risk Management
The notion of an up-front risk register is that you've already defined all the work, and therefore know all the potential risks. This is usually fallacious in practice, but it's still the basis for assuming you can do an up front risk register at all.
Agile frameworks like Scrum are based on just-in-time planning and emergent design. The framework specifically says:

The emergent process and work must be visible to those performing the work as well as those receiving the work. With Scrum, important decisions are based on the perceived state of its three formal artifacts. Artifacts that have low transparency can lead to decisions that diminish value and increase risk.

In addition, the Product Backlog is often an implicit source of risk tracking, which can be made explicit by making it a domain attribute that is included in Product Backlog Items.

Product Backlog refinement is the act of breaking down and further defining Product Backlog items into smaller more precise items. This is an ongoing activity to add details, such as a description, order, and size. Attributes often vary with the domain of work.

The key take-away is that risks are often identified during Backlog Refinement, Sprint Planning, story spikes, Sprint Retrospectives, and other activities within Scrum. For example:

The Product Backlog item for feature Foo can define known risks, and reflect them in whatever way the Product Owner and the rest of Scrum Team consider useful.
Risks should be refined as part of the general refinement process during the Backlog Refinement event.
During Sprint Planning, the risks associated with Product Backlog item Foo should be identified as part of the estimation process if they're not already identified within the Product Backlog itself since the risks will likely impact the level-of-effort for the work item and uncover tasks and story spikes needed to address those risks during the upcoming Sprint.
Risks identified during the Sprint should be addressed during the Daily Scrum, and additional conversations to address those risks should be coordinated and reflected on the Sprint Backlog.
Unexpected or previously-unknown risks that impact the Sprint Goal should be urgent items raised within the Sprint to the whole Scrum Team.
Identified risks should become discussion points within the Sprint Review, and perhaps addressed through refinements to the Definition of Done when necessary.

In other words, it's not that risks aren't addressed. They are simply addressed all the time throughout the process. The main difference with more traditional methodologies is that risk management is part of the ongoing framework and continuous improvement processes, rather than a one-time or up-front activity. In addition, since Scrum is iterative, emergent, and focuses on just-in-time planning, risks are generally addressed at the last responsible moment rather than all at once. There are many reasons for this, but the biggest is that one core principle of agile frameworks is optimizing away unnecessary work:

Simplicity--the art of maximizing the amount of work not done--is essential.

Addressing risks that may never come into scope, or that may be resolved or obviated before they impact the project in any way, is a key benefit of agility. In simpler terms, not spending time identifying risks that don't (yet, or possibly ever) need to be identified or managed is a waste of time, and Scrum specifically optimizes that away by promoting a just-in-time approach to risk management.
Answer: All agile methodologies, especially scrum has core principles and values that if followed duly will mitigate future risks.
The iterative approach and transparency will help in realizing any risk associated with the project. One of Scrum ceremonies, which is Daily Stand-up helps in realizing any escalation or possible risks that may result from this.
In Summary, Agile Methodologies if adopted will mitigate risks in your project.


When sending a text message to multiple recipients, how does one see the other recipients?

Question: I sent a text message through MightyText to 5 recipients. One of them showed me on his phone it indicates the other people the message was sent to. How is this possible? Does SMS include each recipient in each message?
Answer: This is called group messaging. In short, everyone in the group gets replies from all the other group members. You can choose to remove people from the message or isolate specific people to message separately, and for that reason it will list all "participants" in the message.
I am not sure how to view them in your app as I have not used it, but in most messaging apps, when you are in the message thread, there will be an option to view group participants. It may be hidden behind the menu key (3 dots often in upper or lower right, or hardware menu key, if your phone has one). Or it may have its own button. (Tip: in many apps you can find out the purpose of a button by pressing and holding the button)


VW Passat B5 1998 Eletronik issues

Question: I noticed some strange behaviour in my Passat for a long time, the thing is: there are several small elecctrical issues that migh have the same source .. I noticed that when I turn on the ignition, the radio plays normaly (it used to stop while turning on engine), I have no sound in rear speakers out of nowhere (speakers worked for some weeks.. radio is ok, cables also are ok) and when I close the doors from the button on my driver door, the locks from rear doors pupus every time, so they close and open... Does anyone have a clue of what can be going wrong? (PS: I already had to change some cables that led to comfort control module)
Answer: I had a VW B5 from 2001 - 2018, The B5 body has its comfort control module under the floor. The module and its wiring is subject to water-related damage, and the wiring's insulation fails with age.
These varied symptoms suggest that other wires, or the CCM itself, have been impaired, perhaps by water ingress. I'd start by removing the carpeting above the CCM, and making a careful inspection of the wiring. You had to change some wires; I would not be surprised if others have failed as well.
You should also carefully examine the small rubber drain lines from the sunroof, and the drains in the battery compartment below the battery; if any are blocked, they will allow water to enter the passenger compartment.
Comment: I will try that. I also have a water leak on driver floor and can't figure out where it cames from
Comment: Good luck. Another water source is condensate from the air conditioning evaporator. That usually manifests on the right side footwell.

VW Passat B5 1998 Eletronik issues


How to save story progress?

Question: I did save story progress with Franklin's phone, but it keeps restarting everything when I get quit the game.
Answer: I have no idea, but here is how you can try to fix this problem:

Thanks to our fellow member Elena for this one (How do I turn autosave on?)

"Its on the Settings tab, actually. (for me at least)
  Pause>Settings>Saving>Autosave
In PC: Pause>Settings>Saving And Startup>Autosave"

Thanks to our fellow member Dom for this one (How can I save my progress?)

NOTE: Only works when not in mission.
Text about the autosave which may help:

The auto save feature is pretty neat, as it'll save after every
  completed mission, mission replay, random encounter, activity, in
  short: anything of relevance. The auto save feature won't save after
  you improve a skill, however, and if you're in flight school or in the
  shooting range, you'll have to leave those before the auto save
  feature does its job.
However, the quicksave feature (accessible from the cellphone) is
  pretty neat too. Try it out, and you'll never want to go back to your
  safehouse to save, never. Well, maybe you'll occasionally want to
  return to change clothes, watch TV, fetch whatever vehicle is in your
  safehouse garage, or to time travel 6 ingame hours into the future.
  The beauty about the quicksave feature, is that it'll save your
  current position, the vehicle you're currently driving (but not its
  damage, which is kinda nice) and is just perfect to abuse the stock
  market. Just quicksave in front of the assassination missions, start
  the mission, jolt down the stock you'll want to invest in, load the
  previous quicksave, then invest in those stocks as everyone (as you
  won't be able to switch while on assassination mission).
Basically, auto save does a good job, but quicksave does an awesome
  one. Use it well and do it often.
  From our fellow user Nolonar (Do I need to save my game manually?)

Hope this works :)

How to save story progress?


Potential Problems Replacing SSL Digital Certificates?

Question: If you've installed digital certificates on your servers, are there any potential problems when replacing one digital certificate and its key with another?  Are there any hidden ramifications?  I'm building a website that will hold sensitive data.  I have a web server running Nginx, a fileserver that I cross-mount via NFS that serves up static files, and a PostgreSQL database server. Ideally, I'd like to purchase a wildcard certificate with Business/Organization Validation but they're pretty expensive.  What I'm thinking of doing instead is purchasing a cert with Domain Validation to start and then figure out how to get SSL running on all three servers.  Once I understand that process and start getting customers, I would then replace the DV cert with a BOV cert.  What problems, if I, will I encounter if I take this approach?
Comment: An OV cert is a complete waste of money. It confers no real advantage over a DV cert. If you're going to spend money and jump through hoops, get an EV cert to get the green bar in the browser.
Answer: In essence, you're free to replace SSL certificates at will. But if you're going to replace it with one that is less supported by the browsers of your users, you have a problem. For instance, if you were to replace an existing certificate with a Startcom one now, a lot of users will not be able to visit your site, because the Startcom root certificates are not trusted anymore by major browsers, because they violated the rules of the trade.
Another issue can be lack of support for wildcard certificates. Mostly some obscure platforms don't support those. Symbian and Windows CE and stuff. I don't remember the list.
Expensive certificates being a waste of money aside (I even think going beyond domain validation is a waste; users don't know the difference), your approach is valid. After having installed any certificate, you can use a test like SSLLabs to verify all is correct.


Can I retrieve my CoC account using Facebook?

Question: I once have a CoC account. But it was not connected in Gmail. When I checked my tablet one day, some of my apps were deleted including my CoC. When I installed CoC again. I knew I lost my village. So, I was hoping that maybe someone knows how to retrieve it using FB 'cause I connected it in Facebook. I know it sounds impossible. I'm just getting my hopes up. HELP.
Answer: Reconnect via facebook again in the app and it should locate your village for you.
I know when it's connected to google services, it asks you if you want to load up the existing village or start a new one.


What does 'i' mean in Latin

Question: I was reading a story in Latin, and part of it said "i nunc, Mercuri". I don't know what i is in Latin. By the way, this line is said in dialogue. Is it a filler word similar to the "umm" or does it mean something else? I am really confused. Thank you for all the help! I also tried looking it up, but I didn't find any good results. What does it mean? Thanks in advance.
Comment: Hi, M. C. If this answer is now solved, don't forget to click the check to mark it so. Let me know if you have any questions.
Answer: Ī is the imperative singular of eō, īre, "to go". So ī on its own means "go!" (as a command to a single person). In this case, the character is saying "go now, Mercurius".
The other one-letter words in Latin (that I know of) are ā ("away from"), ē ("out of"), and ō (used to address someone). As far as I know, *ū is not a word.
Comment: Also, it seems that no short vowel makes a word on its own.

What does 'i' mean in Latin


Is stats or technical knowledge of poker of any help

Question: I find it quite annoying that I am not able to surpass my 50m mark(on zynga poker )with a much better knowledge of poker since I had earlier crossed it...it is basically the perception of the other player which is single most important factor that can be chalked out as winning point in poker and second is patience....we all know stats are more or less a dirty lie ( quote : there are lies , bloody lies and then stats -: stats is used as superlative degree for lies)...I had won a lot even without even basic knowledge of hands....I have played over 40000 hands at least over multiple accounts and still can't understand the use of my knowledge.To emphasise the question -: I don't think my experience is paying in poker.
Comment: The adage about statistics being lies is really not an attack on statistics at all. Rather, it's an attack on how people _use_ statistics. For example, I once worked for a government research lab where, no kidding, they took 10 samples, they didn't like 9 of them so declared them outliers thus not part of the statistics collection, and used the remaining favorable data point to declare what they wanted. When used in a valid manner, statistics are valid but you need to account for things like margin of error, and be willing to accept undesirable results.
Comment: How can you play poker seriously without real money?
Answer: I'm not exactly what sure what you're talking about when you mention "stats". Playing profitable poker comes down to implementing two concepts:

Identifying your opponents strategy.
Implementing the best response.

The first point is primarily improved through experience. As you play more poker, you will more easily be able to identify what your opponent will do on average. But you can also, if you play online, get concrete statistics on opponent's tendencies through analyzing hand histories — these stats are also known as population tendencies. They will enable you to construct a readless, default strategy that will maximally exploit the population. So a mix of playing experience and analysis of opponent's play will enable you to maximize your ability to quickly and efficiently identify your opponents strategy.
Once you've completed point #1, you'll then need to compute and implement the best, maximally exploitative, response. This is a math-based endeavor. The ability to do this quickly and accurately at the table is the result of a ton of out-of-game analysis. This point is the area of play that beginners and amateurs tend to completely ignore when they should sink a lot of time into it. It doesn't matter if you can consistently come up with good reads if you can't figure out what the best response is.
Honestly, it sounds like you simply play using your emotional responses as the determining factor when it comes to decision making. This might work well against the worst of fish, but the second you begin to play stronger, thinking opponents — or if you actually start playing for real money — you will start to have a much harder time.
It really comes down to this: until you can explain, in a poker hand, why you're doing what you're doing, you aren't going to truly master the game. Don't get me wrong, gameflow is a significant part of profitable play as well, but it remains a part of play, not the only factor in a strategic analysis of poker.
So yes, stats and technical knowledge of poker are of a huge help. You should try reading a book like Poker Math that Matters or the like to get a solid understanding of how basic poker math can improve your game.
Comment: Thank you...really good answer...which I could relate with..but I don't play for real money.. The first and only time I played for real money..was a nominal amount and I won everything with extremely good luck and negligible knowledge
Comment: Your point of thinking opponents and real money...was the distinction I was not able to understand..
Answer: I believe that born talent has something to do with it as well. Some players are gifted and just have a natural feel for the game and therefore make better decisions.
Antonio Esfandiari likes to call it his "radar". There is a reason why pro players are pro. They didn't have the most luck, they are the most talented and gain most skills.
Obviously, luck is also a factor, but not in a long run period.
Maybe you got your 50m mark because you had a bit luck here and there?
Being able to calculate fast, knowing stats formulas, ... Makes you in general smarter than the average poker player. I believe that in fact the amount of talent, the patience  and the IQ (how smart a person is in fact) are the 3 things that make a formula to calculate how "good" a poker player is.
Obviously, there are some other parameters, but the 3 I talked about are the most important I think.
So: Yes it helps you for your game because you are just smarter than the avarage player, but talent and luck are there as well!
Comment: Are you separating talent from IQ? I think the person who has higher IQ is the one who is talented.
Answer: Poker is about rules-of-thumb, techniques, and a whole lot of intuituion. Using game-theory and analyzing scenarios mathematically is, in my opinion, a complete waste of time.
Instead of focusing on stats and math, I believe it is far more effective to analyse your opponent's tendencies qualitatively and therafter use particular techniques to expolit his tendencies. Going over specific scenarios retrospectively and look at betting-% and all that nonsense will yield some clever-sounding conjectures but not much more.
Comment: "Using game-theory and analyzing scenarios mathematically is, in my opinion, a complete waste of time". Most of the top online players in the world will totally disagree with your opinion. I personally think that your opinion is not only wrong, but attests to your own ignorance of these topics more than anything else.
Comment: This response hasn't aged well
Comment: no arguments about this analysis being ad-hoc. That doesn't affect how useful it is. Are you actually claiming that very good online players say that this kind of analysis "doesn't actually help much in the real world"? Just as one example among many, is anyone seriously going to claim that it's useless to have an in-depth understanding of river situations where one player has nuts-or-air and the other has a bluffcatcher? I know that it helps me, and players like Haxton and Sulsky claim that advanced study of GTO helps them massively.
Comment: we can continue this back and forth for a while, but the bottom line is clear, so I'll cut to the chase: it seems *you*, specifically, don't know how to apply the insights gleaned from mathematical and game-theoretic analysis to your game, and you erroneously deduce that no one else can do this either and this is all "a complete waste of time". I wish you luck in your poker career, and would advise you to not share your individual experience with others as if it were universal, because your experience is not universal, and is in fact contrary to many top players.
Comment: Are you kidding? 1. I gave a super-convincing argument, which you admitted it convincing, 2. Your claim was that GTO is useless to everyone. Note the quantifier. My counterexample is that it's not useless to me. That is already a counterexample. I gave a list of other players who claim to be counterexamples.  3. You keep pretending as if the only use in Game Theory for poker is in order to actually play GTO. This is false. One can learn a lot about poker from game theory without attempting to play GTO. But arguments are probably useless: you're being dogmatic on the subject.
Comment: @mobiusdumpling Well, I am in the not-so-usual position of both having lived as a professional poker player and having a degree in applied mathematics. I have done a lot of systematic analysis of poker situations in terms of game theory and mathematics, but it is quite clear from both my experience and opinions of very good online players that *most* of this analysis is only ad-hoc, and that it doesn't actually help much in the real world.
Comment: @mobiusdumpling The scenario you mentioned is actually the only situation where GTO is potentially of any use. That is, a situation where your *range* is comprized of hands either having 0 or 100% equity against your opponent. This is a necessary assumption because in order to play GTO you need full knowledge of range equities between you and your opponent (in most cases, you cannot apply GTO even if you knew your opponent's hand!) So when you think about it, these mathematically tractable scenarios almost never happen.
Comment: @mobiusdumpling Ok, but interestingly, under this whole discussion you have not provided any examples to counter my argument, nor have you said anything to substantiate your claims


How do I access a background terminal program started in startup on gnome?

Question: I installed a terminal server program for my Grandson so that when he logs on to Gnome it automatically starts but he needs to access it to edit commands ocasionaly or to shut it down but I can't find access to the Terminal running anywhere. I see it running in system monitor but can't bring it forward. It's a Startup Program .sh file.
Comment: Are you sure it wasn't simply moved to another workspace? Try pressing the Windows (Super) key and S to see all of your workspaces.
Comment: That just brings up the power button menu....I'm in Gnome Classic...I went ahead and put it back on the work space for now but would eventually like to put it in startup if he can access it somehow.
Answer: If you want to add this to startup, you should be able to find "Startup Applications" in the "System" menu. On Ubuntu 12.04 and 12.10, the "System" menu is in the top right corner. It's in the same place where you power off the computer.
You can simply click "Add", enter your command and a name, and then click "Save".
Answer: I know this question is old but for somebody looking for answer to a similar question, you can see the running background processes started by a terminal program using ps lx


Disrespectful use of "mister"

Question: Is it disrespectful to use "mister" with a person's first name? Examples: Mr. Tom, Mr. Phil, etc.
Comment: And if it is an insult, what is it meant to convey?
Comment: This probably depends more on tone of voice and context than it does the actual words being said.
Comment: Context, context, context. Absolutely any word combination can be disrespectful depending on context. Without context, this question is unanswerable (unless you count "it depends" as an answer). With context, it probably wouldn't exist.
Comment: I have a friend (in his sixties, here in Yorkshire) who often welcomes friends with phrases like "It's Mr Colin". (Some other people in the same social group sometimes do the same, but my impression is that they have caught it from him. I may be wrong about this.) In his case, it is certainly not disrespectful.
Answer: In many English speaking parts of the world, Mr Firstname would be how a servant speaks to an employer. If used outside of that relationship it may be a teasing (or even angry) way to say "you are treating me like a servant." However this wouldn't happen between strangers, or in a context where you weren't sure whether you were being insulted or not. Some children, raised to call all adults Mr Lastname, Ms Lastname etc may transition to Mr Firstname, Ms Firstname etc to indicate the closeness of the family relationship while still addressing the adult respectfully. If you are reading dialog where someone calls another person Mr Firstname, assume it should convey tremendous politeness, but keep in mind excessive politeness ("oh yes sir, thankyou sir, that's so generous of you sir") may in fact be meant sarcastically.
The word Mister alone, in say "listen, Mister, you are keeping me from where I need to be" is rude. It carries a certain "I can't be bothered to learn or use your name, but I am clearly addressing only you" tone to it. Very different from calling the unknown person Sir, for example.
And finally Mr Adjective can be gently teasing or flat out rude. "OK, Mr StickInTheMud, we won't go!" or "Thanks to Mr Rules, it's not happening."
Answer: The intention of the speaker and the peculiarities of the person so addressed determine whether addressing someone as Mr. Firstname pleases or aggravates the addressee. I know that I wouldn't like to be called "Mr. Sven," because it sounds either too familiar or too obsequious or too creepily old-fashioned, going back to a day when—in the U.S. South, anyway—it was standard practice for a black servant or slave to address members of his or her employer's or owner's family as Mister (or Marse or Miss or Miz) Firstname.
Specific instances of being addressed as Mr Actualfirstname aside, there are a couple of forms of generic Mr Firstname usage in which the intention is anything but flattering.
Wentworth & Flexner, Dictionary of American Slang (1961) includes this entry:

Mister Charlie A white man. Some Negro use.

In 1964, however, James Baldwin published a play based on the real-life murder of Emmett Till, called Blues for Mister Charlie, which may have given the slang term a longer life and certainly gave it literary resonance.
Chapman & Kipfer, Dictionary of American Slang, Third Edition (1996) identifies two Mister Firstname slang terms:

Mister Charlie black by 1960 A white man; =the MAN.

and:

Mister Tom n phr by 1960s A black man who wishes to be or has been assimilated into the white middle-class culture; =UNCLE TOM.

Addressing or referring to someone as either "Mr Charlie" or "Mr Tom" when that is not the person's given name is calculated to be offensive and/or dismissive.
Answer: No, it is certainly not an insult, though a trifle quaint and old-fashioned.
A century ago a young boy of a gentry family might have been addressed in that way by the family's servants. Sometimes they would have used 'Master Thomas', or Master William'.
The title 'master' is still used on envelopes when corresponding with a boy who is under the age of about 12 - 'Master David Henderson, 15, Green Hedges Lane, etc.' Though this is less the practice nowadays than it was when I was a child in the late forties/ early fifties.
Outside of Europe, such as in the Far East, some non-native English speakers can be confused over which is the given name and which the surname. (this arises from the fact that in many languages, including importantly Chinese, the family name is written first) It is not unusual for officials, such as airline or hotel clerks etc to call you 'Mr' followed by your Christian name.
Comment: My grandparents, who would inevitably address letters to me using the title "Master,"  would sarcastically address me as "Mister" when they thought I was getting too big for my britches.  "Mister Sartin, do you really expect to eat dinner tonight when the trash from lunch has not yet been taken to the curb?"
Comment: I was born and brought up in Britain and have lived here for all but six years of my life, but I have never known anyone use 'Mister' in the way you describe. Your profile does not tell us where you live, nor the country most familiar to you.
Answer: This doesn't exactly address the question, but it seems at least tangentially relevant.
Here's a situation in which "Mister {last name}" can be used with negative connotation: Sometimes people will refer to others as Mister to stress that they do not have a relevant title. This is done in such a way as to make the point that the speaker has some authority over his counterpart.
It's the height of bureaucratic snobbery.

"Senator Williams, I must urge caution in this matter!"
"I am more than capable of making my own decisions, Mister Tate."

A similar example involving a civilian giving advice to a General:

"Excuse me General, but the men are tired. I don't think we'll make it out of this valley without some rack time."
"Well, Mister Thompson, tell 'the guys' they simply do not have a choice in the matter."

Disrespectful use of "mister"


How to cook rice in an electric oven meant for baking cakes?

Question: Are there any special precautions to be taken? About the water quantity, soaking and timing etc?
Comment: Does it have to be done completely in the oven?  I'd recommend using a rice pilaf technique, but you start that on the stovetop and finish in the oven.
Comment: @Joe See if you can explain that pilaf technique as an answer.
Answer: I make rice in the oven if I'm making a large meal and don't have a burner to spare for the rice. I bake it in an enamel cast iron Dutch oven (you can also use aluminum or stainless steel trays / hotel pans covered tightly with aluminum foil) using the same water-to-rice ratio (2:1) as when I make it on the stove. Cook at 350°F / 177°C for approximately 20-30 minutes, remove from the oven and let it sit, covered, for another 10 minutes. Fluff with a fork and serve!
(Note: The cooking time will depend on whether you pre-soak the rice and also how good your oven is at maintaining a constant temperature. You can check if it needs more time by wiggling the pot/tray a little; if you hear water sloshing around, it needs more time, but if it feels like a solid mass, it's probably done.)
The only problem you might have with this: sometimes the rice on the bottom of the pot gets dried out and sticks to the pot. You can avoid this by boiling the water before you add the rice (on the stove, but I guess you could do it in the oven, too. If you have an electric kettle and you're making a relatively small amount of rice, you can heat the water in the kettle and just pour it over the rice, too).
Answer: There's a technique for pilaf (also pilau, pulav, pulao and lots of other names), which is finished in an oven ... it's possible that you might be able to get away with doing it in only an oven if you used the oven to pre-heat the pan and oil, didn't add vegetables to it (which would cool it down), and also pre-heated the liquid in the oven.

Preheat oven to 350°F / 177°C
Heat the pan with some oil or butter.
Sauté some onion, garlic, and whatever other vegetables you want (mushrooms, bell pepper, carrots, etc.)
Add the rice, and stir 'til it either gets lightly browned or smells nutty. (~3 minutes)
Add liquid (broth / stock / whatever), and bring to a boil.
Turn off the stove (if using a stove)
Cover the pan with a tight fitting lid
Place the pan in the oven for 15 minutes.
Remove pan from oven, still covered, and let sit for 15 minutes more.
Fluff with a fork & serve.

You can add dried herbs before putting it in the oven, as well as stuff that doesn't need a long time to cook (eg, corn or peas).  If you want to add spices or nuts (pine nuts, slivered almonds, etc.), add 'em with the rice before you sauté it.
Answer: I have my special way to cook rice by oven:
At the first keep rice in enough amount of water and salt (1 tablespoon salt for every cup of rice ) for 5 or 6 hours, then on the stove boiling water and rice, if you see some floating rice on top of the water means that the time you must turn off stove and take it's water away, then add enough butter or oil to rice then cover it and put it in oven for 15 mintes.
You'll have very delicious cooked rice.
Comment: I think there is a language problem here. What you describe is suited for a stovetop, and the question asked about an oven.


Is a flight instructor certificate on the same physical card as a pilot certificate?

Question: Are a flight instructor certificate and commercial/airline transport pilot certificate printed on the same physical piece of plastic, or on two different ones?
Answer: I can't speak for other countries, but in the United States, a flight instructor certificate is a separate document from a pilot certificate.  Flight instructor is not a rating which is applied to a pilot certificate. It is an individual laurel with its own privileges and responsibilities separate from a pilot certificate.
Answer: While my flight instructor certificate is similar in form factor and coloring to my pilot certificate, it is a different document. The back of it states that the certificate is not valid, unless accompanied by a pilot certificate No. 12345678 and that the document expires 31 August 2024.
It also contains limitations, such as Airplane Single Engine and Airplane Multi-Engine and privileges such as Instrument Airplane.
Other countries may vary from the United States, which is where my certificate(s) are from.


Gitolite through password instead of a key

Question: Is there a way to make GitoLite work through passwords rather than through public+private keys? For example, to make it in such way that the user can clone the repository only through his/her own gitolite password confirming his/her identity, not by generating a key pair for that.
Answer: No. The entire point of gitolite is that it uses keypairs to determine someone's identity, so that it can manage users, instead of having to manage them on the system.
You could bypass gitolite by giving some users shell access to the repository directories, and having them push directly via ssh (and authenticate with their method of choice, e.g. passwords) but this really would be bypassing it. Gitolite would no longer be able to do all of the fancy things it does, namely checking to see if a given user is authorized to perform a given operation.
Comment: Certainly username/password authentication is not possible with the usual SSH-based authentication used with gitolite, but the (alternative) [http mode](http://sitaramc.github.com/gitolite/http.html) of modern gitolite can use whatever forms of authentication the web server supports (and most web servers probably do support a varienty of username/password authentication methods).
Answer: Password authentication is possible with gitolite.
Let's say user X is authenticated using password.
The workaround is that you need to create a custom script that acts like a shell for user X.
The script redirects the git commands to the gitolite's user using key authentication.
The next step is to make generate a key pair for user X account and add the public key to the gitolite admin's key.
Here is a link that explains it all.


The desired scope of this website

Question: From reading the FAQ, existing question, answers and votes, I am not clear if the desired, long-term scope of this website is to be professional like English L&U, or for language learners like ELL (English Language Learners). It seems we're doing a little bit of both but there needs to be only one standard to evaluate a question and only one audience group to target while writing an answer. There are real examples of a star question on ELL could get a lot of downvotes on EL&U, or a popular question on EL&U gets very little attention on ELL, demonstrating the directional conflicts between the two scopes/intents. So can someone clarify which is the direction for this site?
Answer: I don't think we need to stick to the same policy of EL&U. The only reason why the English site took that decision is that English is so "requested" that it got continuously lots questions on both "topics", especially very easy questions, for example when to use a/an.
We don't have that problem and not one other language site has it, so I think we can simply have both. In the end, our requirements make it so that also potentially easy questions have a sort of prior research that make them "less easy" since there really isn't an answer in the internet.
If you (not just you, all users) see a question that could have been researched more before asking it, you can comment on it asking the OP (be careful with the wording here) to provide their research. If you see that a certain question is really really basic then you can vote to close.
And this brings me to this: the site decides its direction. The community does. So each time you decide to vote to close a question or not to vote to close, you're taking a direction. This is how you shape a site. If the users voted to close the questions they thought to deserve it, future users would be, well, educated, if you get what I mean. I as a moderator will try to keep the quality high by closing, but I'd like to see more regular users voting to close, that way I know that we are all working towards it. Believe it or not, but the policy "less closing so less users will get scared" is not a successful policy. We need to close those that deserve it, this way our site will slowly get its own shape and, yes, new users are intrigued by a polished site. Look at Skeptics SE: it's the hardest site to post on, yet it's one of the more successful.
Hope this helped. :)
Comment: @NS.X. I doubt so. We/I really have few parameters. As long as the question has been researched and it's well-written, on topic, ecc, I think any question would be OK for our site. No reason in denying some questions just because they come from learners a priori. It's not convenient (we have few visits) and they still can bring quality to our site. We just need to educate the users on how to ask, not what to ask. That's how I moderate and I think it works. :D
Comment: I see your perspective but the broader/lenient the scope is, the more difficult moderating work will become since you really want to apply different standards on different type of questions and educate users why the rules appear inconsistent. Maintaining style is another big challenge, etc.
Answer: Those that participated during the proposal stage at Area 51 would have a better idea on the original intent of this site. We can roughly classify users of this site into three main groups:

English speakers learning Chinese
Chinese speakers learning English
Bilinguals who are interested in Chinese

If I am not wrong, this site is launched mainly because of the collective effort from the first and third group. This explains why we have questions predominantly in English. The second group came in much later and are put off either because:

they get their questions closed (because they are obviously trying to improve on their English), or;
they gave wrong answers and get down-voted as a result of not being
able to understand the question fully (especially when it comes to
etymology), or;
they cannot understand the FAQ and fall foul of the rules here (example giving one liner answer with no explanation).

What I feel, after seeing what was done in ELL and an upcoming site dealing with Chinese Emigration, is that perhaps this site should be more appropriately called Chinese Language for Learners. Then we can have another site in pure Chinese to capture an important group that has been totally missed out:

Chinese experts who only know Chinese

I think ELL should accept questions from the second group and perhaps we can funnel them there. But, at the same time, I also think it would be more difficult for them to get answers there as it has to cater for a wider audience. Unless we are adopting a very lenient approach, which makes moderating harder and inconsistent, putting off new users, I agree with you that there is a need to make it clear in our scope.

The desired scope of this website


MongoDB specifying shard key and sharding strategy

Question: What is the syntax to state that a collection is to be sharded as location based, while using the range based sharding strategy. I know you have to use the the sh.shardCollection() command, but what arguments do I use in it?
Answer: As per MongoDB documentation here Ranged-based sharding involves dividing data into contiguous ranges determined by the shard key values. In this model, documents with "close" shard key values are likely to be in the same chunk or shard. This allows for efficient queries where reads target documents within a contiguous range. However, both read and write performance may decrease with poor shard key selection.
Ranged sharding is most efficient when the shard key displays the following traits:

Large Shard Key Cardinality
Low Shard Key Frequency
Non-Monotonically Changing Shard Keys

For Example
A sharded cluster using the field X as the shard key. If the values for X have a large range, low frequency, and change at a non-monotonic rate, the distribution of inserts may look similar to the following:

Use the sh.shardCollection() method, specifying the full namespace of the collection and the target index or compound index to use as the shard key.
sh.shardCollection( "database.collection", { <shard key> } )

For further your ref here and here
Answer: Zones can help improve the locality of data for sharded clusters that span multiple data centers. A zone is a grouping of documents based on ranges of shard key values for a given sharded collection. In a balanced cluster, MongoDB directs reads and writes for a zone only to those shards inside that zone. You can associate each zone with one or more shards in the cluster. A shard can associate with any number of zones.
You can create zones of sharded data based on the shard key. You must use fields contained in the shard key when defining a new range for a zone to cover. For a compound shard key, the range must include the prefix of the shard key.
Reference: Zones in Sharded Clusters

A sharded cluster deployment has (a) Config server, (b) mongos router, and (c) Shard servers (shards). For a newly created cluster there will be no sharded databases or collections. From mongos you can see the current status of the cluster using the command sh.status().
From the question post:

What is the syntax to state that a collection is to be sharded as
location based, while using the range based sharding strategy.

Create a Zone:
Add shards to a Zone. Associate a shard with a zone. A single shard may have multiple zones, and multiple shards may also have the same zone.
sh.addShardToZone("my_shard_name_1", "my_zone_name_1")

Do this for the shards and zones you are working with.
Create a Zone Range:
Associate a range of shard key values with a zone. Note the shard key is for a collection to be sharded. Any given shard key range can only have one assigned zone.
sh.updateZoneKeyRange(
    "my_database.my_collection",
    { my_shard_key: "my_val_min" }, { my_shard_key: "my_val_max" },
    "my_zone_name_1"
  )

Do this for the zones you are working with.
View Existing Zones:
Use sh.status() to see the zones associated to each shard in the cluster.
Use the following queries on the config database to view the shards associated with a zone or the keys range associated with a zone.
use config
db.shards.find({ tags: "my_zone_name_1" })
db.tags.find({ tag: "my_zone_name_1" })

Shard a Collection:
From this point, you can shard a database and distribute a collection's data as per the zones setup earlier. Assuming the database to be sharded is
"db_test" and the collection is "coll_test" and the shard key is a field called as "my_shard_key" for the collection (the shard key field is the same as in the Create a Zone Range above):
use db_test
db.coll_test.createIndex( { my_shard_key: 1 } )
sh.shardCollection("db_test.coll_test", { my_shard_key: 1 } )

Verify the sharded collection with the command sh.status(). Further, you can add data to the sharded collection and perform query operations.


Blurred vision clearer with use of 2 mirrors

Question: I have been having trouble with my vision. blurry and shadows.  I realized that when I use a hand held mirror to see the back of my hair that is being reflected by another mirror behind my back I can see so much clearer.  why is this?  Eye dr. has not been able to help me so far.
Comment: Probably that this is giving you a very small field of view. Your vision on-axis is probably better. Try holding an opaque card with a small hole upto your eye -  you will see a similar effect
Comment: Has the optician ruled out that you need eyeglasses? It's not implausible that the mirrors may be slightly imperfect and are introducing some optical correction that matches a defect in your vision. Also, what happens if you try to look at other things through the two mirrors? Also, are you looking through the mirrors with both eyes forward and the mirror at a reasonable distance, or are you pulling your eyes to one side (which can introduce correction), or maybe using only one eye (which is better than the other)?
Comment: I have been to the same eye doctor that did Lasik surgery on my eyes about 20 yr ago .  He tested the muscles in my eyes and had me try at least a dozen pr of contacts. no help.  I just noticed this with the mirrors in the last week . I could actually see individual hair on the back of my head and can't even see my eyes to apply eyemakeup! .didn't understand why but now will try to look at other images and post that.  thanks Martin and Steve!  oh, I probably looked from either side and with both eyes forward as well.. I didn't know if it might give an insight to the problem with my vision.
Comment: If you're farsighted, this makes sense. By looking at objects through two mirrors, you're increasing the distance the light rays travel to get to your eye, so the image would become sharper if your vision improves with distance.
Answer: What comes first to mind is the fact that the distance from eye to mirror to mirror to back of your head is a relatively long distance.  You could try looking at the back of someone else's head (or a printed page or anything else with a lot of detail) at various distances and see if there's a distance at which you see better detail.  If that doesn't work, then I would lean toward @Steve 's guess that one of your mirrors might be distorted.  You could test that guess by using a different mirror. Either situation would suggest that you need different eyeglasses.


Starting two or more different martial arts at the same time

Question: Is it simply like learning two different languages at the same time? If so will it be easier to differentiate if the two styles are very different? For example, Kyokushin Karate and Judo.
Comment: Possible duplicate of [Karate and Judo?](http://martialarts.stackexchange.com/questions/6773/karate-and-judo)
Comment: Some school offer two art that compliment each other and will try to not make it confusing if you decide to do both (I would suggest to find that). (for example) If you learn how to punch one way in one class, and an other way in the other, it will be hard to have good form. You might also start questioning a lot of what you learn "here they say this is better but in the other class they say it's not".
Answer: It generally takes two/three classes per week (so four/six hours?) to progress in a martial art. Doing two arts, you will need that in both. Three arts brings you to around fifteen hours! That is a lot to fit in a normal day with work and social activities around it. In addition, unless you are really fit, your body will not cope with the strain of that amount of exercise.
Mental space is a little different but the more similar the arts, the more confusion will creep in. So, you might spend time being confused.
I would pick on, get to first dan (or whatever "I know the basics" is in that art) before picking a new one. Although, the more arts you "know" does not make you good at any of them:

I fear not the man who has practised 10,000 kicks once, but I fear the man who has practised one kick 10,000 times. -- Bruce Lee
Answer: It's a big commitment to put sufficient time and effort into just one martial art to really get good and advance quickly. Most people who start a single martial art only stick to it for a few months. Biting off more than you can chew is probably not a recipe for success. Training in two martial arts is twice the effort, and if both are intense high-contact styles (as both Judo and Kyokushin are), that may be a cheque your body isn't prepared to cash. (You did say "starting"... it's a somewhat different story to already be proficient in one art and add another that complements it.)
If the reason you are contemplating this is that you are after particular aspects of both, it may be wise to consider finding a single martial art that combines whatever aspects you like about the two you are considering. One example (but not the only one) is Hapkido, which very roughly speaking combines the strikes and kicks of Karate/Taekwondo with the throws and falls of Judo, and also a lot of joint locks, escapes from holds, etc. Sometimes you can also find schools that combine Jiujitsu and boxing, if what you're after is to get skills in both grappling and striking.
Answer: When you approach an opponent in Kyokushin you have no choice but strike because they have no throws. You might feel yourself uncomfortable after learning some judo throws because Kyokushin allows an opponent came closer than usual and you are not allowed to throw him but only strike.


Nginx load balancer shows wrong site on failover server

Question: I have five websites and I have three servers, all running nginx.

Primary server
Load balancer
Failover server

Each website has it's own primary server but they all share the same failover server. My load balancer is set to send all traffic to each website's primary server. Only if that primary server goes down will the load balancer send traffic to the failover server.
For each website, I have a separate nginx config file on the load balancer that is similar to this:
upstream website {
        server 188.8.131.52 fail_timeout=3s max_fails=3 weight=10000;
        server 188.8.131.52;
}

server {
        listen 80;
        server_name www.websitename.com;
        client_max_body_size 150M;
        location / {
                proxy_pass http://website;
        }
}

server {
        listen 80;
        server_name websitename.com;
        client_max_body_size 150M;
        location / {
                proxy_pass http://website;
        }
}

With that config file, everything works just fine. All traffic is sent to the primary server, if the primary server goes down, the traffic will be sent to the failover server.
The problem comes with the failover server. I have five different websites on the failover server, all with their own separate nginx config file in the sites-available directory. The problem is, when traffic is sent to the failover server, nginx is showing the first available config file and the associated website, not the correct website.
Each website config file on the failover server looks like the config file below. Of course, each one has a different URL and root directory but that is the only difference. In this case, I have matched the example config file to be associated with the example load balancer config file:
server {
        listen 80;
        listen [::]:80;

        root /usr/share/nginx/html/websitename;

        index index.php;

        server_name websitename.com;

        location / {
                try_files $uri $uri/ /index.php?$args;
        }

        location ~ \.php$ {
                try_files $uri =404;
                fastcgi_split_path_info ^(.+\.php)(/.+)$;
                fastcgi_pass unix:/var/run/php5-fpm.sock;
                fastcgi_index index.php;
                include fastcgi_params;
        }
}

Also, I am not sure if this matters but the DNS A record for the website is set to point to the load balancer.
I am quite certain the problem lies with the fail over website config files but I don't know what is wrong. I would appreciate any help, thanks.
Answer: It looks like I found out the answer to this.
I needed to add the line proxy_set_header Host $host; right under the proxy_pass lines on my load balancer config files.


Get creation date and time of records in data extension

Question: We have dynamic CRM system which syncs data to marketing cloud however i need to find when the records were created in data extension ,
Sad part is i dont have default date field in it.
Help Please! , Thanks
Answer: What type of integration are you using? If you are receiving the records either via API of FTP, you can add a date field to the data extension, and set its default value to current time. This way, you will get the creation time of each of them:
Comment: Thanks for the reply , data is already loaded into the Data extension via api and i'll take care to add the date field from next time


Can you add separators to Docky?

Question: Is it possible to add more separators to Docky? If so, how? I've checked through the preferences window but I didn't see anything about adding separators there.
Comment: Too bad.
Docky is a great app, but I'm switching to Cairo-Dock for it's lack of configuration features.
Answer: No, you can't add separators in Docky.
The developers have said that this feature is not planned for future releases either.
Answer: Robert Dyer said earlier this year in response to the question "How do you Add a Separator line?":

You dont. There is no way to add these yourself and no plans for such a feature.

He went on to explain:

Docky is all about simplicity. Being able to add separators gives you no new functionality. You can already arrange/group launchers however you want. That little bit of separation between them really doesn't give you anything worthwhile and we try to keep the feature set somewhat small and not present the user with too many options (we pick what we feel are the 'sane' options).
Comment: Your link is broken. I assume you also meant to link here: https://answers.launchpad.net/docky/+question/95774
Answer: Yes you can. :-) But its a little and not very pleasant trick.

Simple create a fully transparent PNG with resolution of 32x32 pixels.
Create a launcher. Name it "space" or something and assign it an transparent PNG as icon.
Launcher will execute something like "echo > /dev/null" which does "nothing" and very quickly.
Add new launcher to dock by Drag&Drop

Done. But... This trick has a little problem. When mouse is over this "separator" it will be labeled as "space" (or something you entered in the launcher name).
Works for me very well. :-)
Have a nice day.

Can you add separators to Docky?


Medians which lie in sequence of even length.

Question: Given a sequence of numbers say [1,2,2,2,4,3,3] from this sequence how many sub-sequences in order can be formed in which the median will lie in the sub-sequences itself. I have found that for all sequences of odd length it will hold true. Therefore total number of sequences with odd length are nC1+nC3+nC5+...+nCn for current array n=7. Now I have also figured out that all the sequences of length 2 which can be formed are 3C2 + 2C2 i.e C(3,2) + C(2,2) That is it will be only possible if we have both the same in above example it will be [2,2] [2,2] [2,2] [3,3] the elements will be treated different if they are at different indices in sequence. How I will find number of other sequences of length 4,6... and other even length sequences.
Comment: I mean to say that the in the sub-sequence the order in which number are present should be followed that is for a sub-sequence Ai,Aj,Ak,Al...., 1<=i<j<k<l<.. and so on where i,j,k,l are positions of numbers in original sequence.
Comment: This problem was taken from a [contest](https://www.codechef.com/NOV18B/problems/GMEDIAN) that closed 12 November 2018.
Comment: Can you clarify? When you say "in order", do you mean that the subsequences must be non-decreasing? Or just that the indices of the elements must be increasing?
Answer: Reposing the answer now that the contest has ended

First note that the problem does not change if we first sort the sequence. So the number of subsequences that contain its own median in the sequence $[1,2,2,2,4,3,3]$ is the same as that of $[1,2,2,2,3,3,4]$.
Suppose that we had a (sorted) even length subsequence $a_1,...,a_{2n}$ that contained its own median. Then the elements $a_{n}$ and $a_{n+1}$ must be equal. As in your post, you identified that the possibilities in your example for the elements $a_{n}$ and $a_{n+1}$ were $[2,2]$ (with multiplicity $3$) and $[3,3]$. The only possibilities for the median are those elements that appear multiple times in the array.
For an even length subsequence $a_n$, let the possible medians be the set $\text{med}(a_n)$. For any element $a$ in the sequence, let $l(a)$ be the number of elements in the sequence less than $a$ and let $g(a)$ be the number of elements in the sequence greater than $a$. To construct a subsequence from a given $m\in \text{med}(a_n)$, then for some $k\le g(m), l(m)$, select $k$ elements that are less than $m$ and $k$ elements that are greater than $m$, and add them to the subsequence. The number of ways to do this is
$$
\sum_{m\in \text{med}(a_n)}\left(
\sum^{min\{g(m),l(m)\}}_{i=0}\binom{g(m)}{i}\binom{l(m)}{i}
\right)
$$
However, this solution has a major issue. It assumes that there are always exactly $2$ elements in the subsequence equal to the median $m$. There must be at least $2$, but there could be more. Consider the subsequence $[1,2,2,2]$ from the example sequence. To fix this issue, let $n(m)$ be the multiplicity of $m\in \text{med}(a_n)$,
$$
\sum_{m\in \text{med}(a_n)}\left(
\sum^{(n(m)-2)}_{x=0}
\sum^{(n(m)-2-x)}_{y=0}
\left(
\sum^{min\{g(m)+x,l(m)+y\}}_{i=0}\binom{g(m)+x}{i}\binom{l(m)+y}{i}
\right)
\right)
$$
Using Vandermonde's identity, we can simplify the innermost sum,
$$
\sum_{m\in \text{med}(a_n)}\left(
\sum^{(n(m)-2)}_{x=0}
\sum^{(n(m)-2-x)}_{y=0}
\binom{(g(m)+x)+(l(m)+y)}{(g(m)+x)}
\right)
$$
This equals the number of even length subsequences that contain their own median.


Why is CircuitSampler ignoring number of shots if backend is a statevector_simulator?

Question: I am calculating the expectation value of an operator using the CircuitSampler class as mentioned here. Now, I was getting exact same result for the expectation values even when I specified different number of shots. It turns out that in the method convert of CircuitSampler ignores the number of shots if the backend is a statevector_simulator. Why is that the case? Also, what is the difference if backend is a statevector or something else?
Answer: The Statevector is a vector of length $2^n$ (where you have $n$ qubits) in which the square of each element's absolute value gives you the probability of getting that bit pattern.  So, for example, $[\frac{\sqrt3}4, \frac{\sqrt5}4, \frac{\sqrt6}4, \frac{\sqrt2}4]$ indicates that you have a
$\frac{3}{16}$ chance of getting $|00\rangle$, a $\frac5{16}$ chance of getting $|01\rangle$, etc.  This is a calculation that can only be done by a simulator keeping track of every possible state, and not by an actual quantum device with $n$ qubits.
Since a statevector simulator knows the exact odds of every possible result (save for floating point errors), it can give a precise answer.
Simulators that return shots rather than statevectors often generate a statevector internally, and then use a method similar to Statevector.sample_memory(shots) to emulate taking quantum measurements on a statevector.  The results look less clean and more like coin tossing.
Comment: Does this mean that using `statevector_simulator` with `CircuitSampler` doesn't simulate a quantum computer at all? Does it simply do a matrix vector multiplication to get the expectation value?
Comment: I've never implemented a simulator myself, but I suspect this is what all of them do.  There is no other way (that I know of) to simulate a quantum computer classically.
Answer: This behavior is called "Aer fast expectation". It is enabled by default if operator primitives are Paulis and the used backend is Aer Qasm backend. It has the advantage of being fast. However, if you pass a noise model to the simulator, it will be ignored.
If you are using ExpectationFactory you can disable this behavior by setting include_custom to False so that PauliExpectation will be used instead of AerPauliExpectation
observables = [
    X^X,
    Z^I,
    Z^Z,
]

circuit_sampler = CircuitSampler(quantum_instance)
exp_converter = ExpectationFactory.build(observables[0], None, include_custom = False) # <== here

list_op = ListOp([StateFn(obs, is_measurement = True).compose(StateFn(circuit)) for obs in observables])

observables_expect = exp_converter.convert(list_op)
observables_expect_sampled = circuit_sampler.convert(observables_expect)

observables_results = np.real(observables_expect_sampled.eval())
print(observables_results)

Comment: I also notice that specifying  `statevector_simulator`  as the backend returns much more accurate results than specifying `aer_simulator` in this case. Why is that the case?
Comment: Does statevector_simulator with CircuitSampler simulate a quantum computer at all? Does it simply do a matrix vector multiplication to get the expectation value?


Installing dropbox for centos 7, requiring fedora 21

Question: I have been using dropbox for linux on my workstation with centos 7. However, recently, dropbox requires fedora 21, but my fedora version is 19. Is there any way to update fedora on centos 7? Or I just give up using dropbox?
Answer: If you are getting that information from this page: https://www.dropbox.com/install-linux then that just means that the Dropbox package was designed for Fedora 21 (or Ubuntu 14.04). CentOS 7 is derived from RHEL 7 which is derived from Fedora 19/20. CentOS (and RHEL) have both been updated to the minor release versions of 7.6 so any of the needed components such as libraries are there.
You don't need to upgrade your "Fedora version". What you are seeing just means that your version of CentOS was derived from that particular version of Fedora. I've installed Dropbox on CentOS 7 and RHEL 7 and it works with no issues just as yours is working. It even works on CentOS 6 and RHEL 6 even though they are derived from older versions of Fedora.


iTunes - Sorting issue. Song names that start with 'the' or 'a'

Question:
I'm sorry guys if this is an easy fix. But I really couldn't find any useful info about this anywhere. iTunes ignores the 'the' and 'a' in the song names and sorts them this way. as you can see in the screenshot. This makes it extremely hard for me to crosscheck my folders with the iTunes.
Any help is appreciated. thank you
Answer: iTunes will generally import songs with a few different metadata fields. Check out this example where the name field is different from the sort as field:

As far as I know, unless these fields are updated for every song in your library, it will sort them as if the `a` or `the` weren't present.


Does Kombucha Tea spoil if left outside of refrigeration?

Question: I accidentally left an unopened bottle of GT Kombucha tea outside the refrigerator. Discovered it the next day... It was in my basement, thus cool and out of sunlight. No where on the bottle, could I find where it says to "keep refrigerated" OR "refrigerate after opening"--although it is refrigerated in the store. and this is also how I keep it.   Does anyone know if this bottle would still be safe to drink?  Especially if it tastes and smells normal?
Answer: Seems as if it must be kept refrigerated. First I found that it ships refrigerated and has a somewhat short shelf life. Then, I found a picture of the label and it clearly states 'KEEP REFRIGERATED. - DO NOT SHAKE.'
Here's a link to the Amazon page where you can see a pic of the label.
Answer: Kombucha is usually made by fermentation, typically at room temperature. It is acidic and has live cultures (if unpasteurized), so I would not worry about spoilage from infection after a few days out of the fridge.
Answer: Kombucha is made by fermentation. If you leave it out of the fridge it may  undergo a second fermentation, which will make it more vinegar-y and carbonated but it will still be safe to drink
Answer: I drank a bottle of unopened, bottled kombucha that came from a 6 pack that had been sitting in our garage for about 2 weeks - and that night I felt like I was giving birth to an alien.  DO NOT DO IT.  I've given birth 3 times and this was like a 4th.
Comment: Hi @LILI, in most cases, one person's health related experience is not very helpful in answering questions like this.  A better response would include facts about how and why kombucha might (or might not) be safely stored at room temperature.


Connection/Voltage-Detection/Voltage and Current Regulation

Question: I'm using a Raspberry Pi zero for a drone. The Pi will be powered by a 11.1V battery. To reduce the voltage and current going into the Pi I'm thinking of using a buck boost converter.
If I use this converter, will it be compatible? And for voltage and battery percentage detection purposes, do I also use a voltage testing measurement unit or will the buck boost converter be good enough?
Answer: To step down the battery voltage, you need a buck converter. Adding the "boost" feature reduces efficiency, adds cost & complexity with no benefit.
The converter you've found on that website is unfortunately typical of the trash they push on the gullible - it has "disappointment" written all over it. The seller's description is gibberish. At one point, they even admit:

but the voltage and current meter values are not accurate;

Their "Product Description" is a parody on Chinese goods - rife with illiteracy and incoherent claims. Here's how it looks today:

All of that said - the concept of using a dc-dc converter to maintain a regulated voltage from batteries is very sound - in fact, it's the only way to go really. But a sound idea executed poorly is not going to be a positive experience for you. FWIW, there are vendors in the world that are competent and honest. You might find something useful in this collection of buck converters.
Comment: My only concern is finding a buck converter/voltage regulator that can be programmed so it can show its reading on the computer/mobile screen remotely. Are the ones you posted programable?
Comment: I don't know - you could ask the vendor. If not, there are many electronics mfrs (think TI, Analog Devices, etc) that make hardware specifically for ***managing batteries***. Try searching for a "coulomb counter".


How do I switch node templates based on arbitrary critera

Question: I'm trying to switch the node template file based on a variable, in drupal 6 you could simply set  $vars['template_file'] = 'node-whatever'; from with the preprocess_node() and name the new node template file node-whatever.tpl.php.
I drupal 7 this is gone. I looked through the docs and it appears that in Drupal 7  its   $vars['theme_hook_suggestion'][] = 'node--whatever'; but this is not working for me. Am I doing something wrong? is there a naming convention that I'm missing? The documentation is a little confusing
Answer: Indeed, in D7 the template suggestions are an array of suggestions, in the order of importance. You've got 99% of it, but your dashes need to be underscores. Try:
function THEME_preprocess_page() {
  $vars['theme_hook_suggestions'][] = 'page__whatever';
}

function THEME_preprocess_node() {
  $vars['theme_hook_suggestions'][] = 'node__whatever';
}

Why underscores instead of hyphens? From the Drupal API docs:
  // Hyphens (-) and underscores (_) play a special role in theme suggestions.
  // Theme suggestions should only contain underscores, because within
  // drupal_find_theme_templates(), underscores are converted to hyphens to
  // match template file names, and then converted back to underscores to match
  // pre-processing and other function names. So if your theme suggestion
  // contains a hyphen, it will end up as an underscore after this conversion,
  // and your function names won't be recognized.

Comment: also I had $vars['theme_hook_suggestion'] rather than $vars['theme_hook_suggestions'] (plural) ... stupid
Comment: Thank you so much for pointing the underscore thing out. I spent over an hour trying to figure out why my template was not discovered - and it contained hyphens.
Answer: Some Drupal 7 example where you're loading different TPL template based on taxonomy term wich Page has (field_page_category):
/**
 * Override or insert variables into the node templates.
 *
 */
function phptemplate_preprocess_node(&$vars, $hook) {
  $node = $vars['node'];
  switch($node->type) {
    case 'page':
      $tid = $node->field_page_category[LANGUAGE_NONE][0]['taxonomy_term']->tid;
      $parents = taxonomy_get_parents_all($tid);
      foreach ($parents as $tid => $term) {
        $category = ereg_replace('[[:space:]]', '-', $term->name);
        // Suggest a theme name, see: https://drupal.org/node/1089656
        $vars['theme_hook_suggestions'][] = 'node__page__'. strtolower($category);
      }
    break;
  } // end: switch
}


How to store images into database using php in android?

Question: Hi i want to store images into database.I created table with fields like imgID tinyint, image blob. But i have a little bit confusion on it.Can any body tel me how can i do that? Thanks in advance.
Answer: I've always stored the image file name/location. And just linked to it ... without storing the image as a blob.
Its simpler: database won't get massive and functionally it does almost the same thing.
Answer: You should convert Images/Bitmaps into byte array and then add it to the database as blob.
Read this post


Meaning of what a difference it made

Question: SŌSUKE had been relaxing for some time on the veranda, legs comfortably
crossed on a cushion he had set down in a warm, sunny spot. After a while,
however, he let drop the magazine he had been holding and lay down on his
side. It was a truly fine autumn day, the sun bright, the air crisp, and the
clatter of wooden clogs passing through the quiet neighborhood echoed in
his ears with a heightened clarity. Tucking one arm under his head, he cast
his gaze past the eaves at the expanse of clear blue sky above. Compared to
the tiny space he occupied here on the veranda, this patch of sky appeared
extremely vast. Thinking what a difference it made, simply to take in the
sky in the rare, leisurely fashion afforded by a Sunday, he squinted directly
at the blazing sun for a few moments, then, averting his eyes, rolled over to
his other side and faced the shoji.
Make a difference mean: have a significant effect on a person or situation.
I think here "what a difference it made" refer to Sosuke and his good feeling after watching the sky. Am I right?
Source: The Gate by NATSUME SŌSEKI Translated by WILLIAM F. SIBLEY
Answer: Yes, you are right.
More specifically, it refers to the clause "simply to take in the sky in the rare, leisurely fashion afforded by a Sunday"
That's what made such a difference to him.

Meaning of what a difference it made


Access 2016 problems with Thread usage c#

Question: I'm trying to open access connection from a C# application. The connection is being opened the below method :
<code>            ADOX.CatalogClass cat = new ADOX.CatalogClass();

            System.IO.File.Delete(_AccessDatabaseName);
            cat.Create("Provider=Microsoft.ACE.OLEDB.12.0; Data Source=" + _AccessDatabaseName + "; Jet OLEDB:Engine Type=5");
            cat = null;

            _ErrorMessage = "";
            return (true);
</code>
Everything works fine until i call these methods using a background worker/thread with office 2016.
I get the below error :Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
Sometimes even this : No error message available, result code: E_UNEXPECTED(0x8000FFFF).
It seams the ldb of the access is still opened, so when i cannot access the mdb file after creating it in order to create/insert into any other table.
I installed accessruntime_4288-1001_x64_en-us.exe and AccessDatabaseEngine_X64.exe but same errors.
Even when trying to create the mdb using cat.Create the application freezes until i have to force close it.
Any help would be great.
Comment: you are creating an instance of `cat` then setting it = to `null` are you trying to access that anywhere else in your code..? very hard to determine what the issue is when you do not post all of the relevant code that relates to the actual method call.. also why are you deleting and recreating the database? what type of access rights are you granting to the file.. ? if you are opening a file..where are you closing it so that it can be reopened in another / separate stream..?
Comment: @MethodMan It's a long process, since i'm copying data from SQL to Access MDB through c#. I'm creating the database using this method. Than select data from SQL, modify it and re-writing it to access mdb using another method.
Answer: I have been looking for a proper solution for the same issue but without success. My workaround is either not to use any background threads or , if background threads needed, using connection string with 'OLE DB SERVICES = -1' to enable pooling so that ldb or laccdb could be reused by other connections without creating new one. However, the pooling will render reopening connection errors if the lock file disappears after timeout (1 minute) in 2016 Access Engine. Thus, a stupid solution is to create another thread to open the connection and close it every minute.
It seems to be a bug in MS Access Engine 2016. I am hoping someone could help me not to use this crazy workaround.


Can I use my Bitcoins to buy household commodities just like ordinary money?

Question: Can I use my Bitcoins to buy household commodities just like ordinary money?  You see, I'm a newbie and have yet to learn the basics including all the facts about Bitcoins.  However,  I want to be ascertained as to whether my time and efforts in learning the trade will be rewarding in such a way that,  I'll be able to use whatever amount of Bitcoins I may earn someday to actually purchase things from the nearby store.
Answer: Currently there are relatively few shops that accept Bitcoin. If you want to know whether your local stores accept it, you will have to ask them. (Be prepared to be told "no" or more likely "I have no idea what you are talking about.")
Your title about "legal tender" is actually asking something different. "Legal tender" is a legal term, referring to a method of payment that must be accepted to settle a debt. As far as I know, Bitcoin is not legal tender in  any jurisdiction. However, people are still free to accept it if both parties agree (unless other local laws forbid it). In any case, legal tender is irrelevant to retail purchases, where no goods have already changed hands and no debt exists ahead of time. The seller can decide what forms of payment they do or don't want to accept.


Add downloadable zip file to cms page

Question: Using Magento2.3.4 Enterprise Cloud we need to create a cms page that will list links to various zip files that will contain marketing material. My issue is where do I upload the zip file too as in what path? I tried adding the zip file to the Magento_Theme/templates directory but that did not help.
Answer: If you want the zip files to be publicly accessible links (it sounds like it), you just need to upload them to a folder somewhere inside pub/media.
For example:
MAGENTO_ROOT/pub/media/marketing/example-1.zip
MAGENTO_ROOT/pub/media/marketing/example-2.zip
MAGENTO_ROOT/pub/media/marketing/example-3.zip

CMS Page Content:

Example 1

Example 2

Example 3

Comment: It is possible on commerce cloud. Pub/media should be writable, but pub/media should not be tracked in your git repo. You'll just manually upload the files
Comment: With Magento cloud, most of the file system is read only, with the exception of a few files and folders (var, app/etc/env.php, pub/media).
Comment: I am on Magento Enterprise cloud. When I do a git push and pull I do not seem to be able to push/pull from/to the pub folder. Maybe I just need to edit my .gitignore file however is this possible to edit on Magento2 enterprise cloud?
Comment: Thank you for the help.

Add downloadable zip file to cms page


Using External Data in SharePoint 2013

Question: Hi i am new to SharePoint, i have been given a requirement and i am not able to find the right approach.
We have a SharePoint portal which keeps track of employees details, very recently we have installed bio-metric machine in our office and that machine sends data to a .net application which uses sql server to store the data.
I need a way to fetch that data(bio-metric machine data stored in sql) and populate a list in SharePoint every time there is a change in data sent by biometric machine.
Please help me find the right approach to achieve this.
Answer: As data stored into the SQL Database, then you have a choice to use BCS. To access external Data from SharePoint, you have to use the BCS.BCS enable you to create External Content Types and External Lists from SQL Server Database.
Deploy a Business Connectivity Services on-premises solution in SharePoint 2013
How to: Create external content types for SQL Server in SharePoint 2013
Comment: Thank for your reply. That was my first thought too, but the problem is i have to add this data to existing list without making changes to its current content types, so is it possible to add the data from sql to existing list.
Answer: Another alternative that may be worth exploring is to use SQL Server Integration Services (SSIS). There's package on Codeplex that integrates SharePoint with SQL Server for data integration. See here for more details -
Extracting and Loading SharePoint Data in SQL Server Integration Services

Using External Data in SharePoint 2013


How do I get 5V 10A output from a 3.7V li-ion battery for 64x16 led matrix display module?

Question: Please I am new to electronics and new here. I'm doing a project which involves the use of a 18650 li-ion battery (or two as may be the case) to power a 64x16 led matrix display module which (according to seller info and datasheets) takes up a large 10A and 5V. I've read posts which exposed me to BMS modules. I have also researched on the bms modules but seem to find only those of 5A (considering the 18650 works with 3.7V).
Can I find a bms module that fits into this specification as a single module?
Does connecting two modules of 5A bms in parallel result in both working as one unit of 10A?
Will I still need a li-ion charger module to work with the BMS module(s)? (considering I'll have to recharge the batteries)
Comment: You need to provide links to the datasheets for the battery and BMS.
Comment: Are you quite certain this is a good idea? Please note that your matrix requires 5 volts x 10 amps, or 50 watts. A 3.7 volt, 3000 mAh cell will provide about 10 Wh, so the matrix will only run for about 12 minutes or so (10/50 x 60 minutes). Two cells will provide about 24 minutes, and this assumes a perfect voltage converter to get from the battery to 5 volts. Assume 80% system efficiency and your time drops to about 10 minutes/20 minutes. Are  you sure this is adequate?
Comment: Fahgeddaboudit!
Comment: any reason for choosing a 3.7V li-ion? why not just go for a single larger battery pack and step it down to 5V with a switching regulator? this is much easier than using BMS to parallel enough batteries to satisfy your power requirements
Answer: What you want to achieve will be very challenging, even for someone with plenty of experience in electronics. For a newbee like yourself: forget it
Why?
You're asking too much from those 18650 cells. That LED panel wants 5 V * 10 A = 50 Watt. That's a ridiculous panel BTW but I digress.
A reasonable current that a decent 18650 cell can deliver is about 2 A at an average voltage of around 3.6 V: 2 A * 3.6 V = 7.2 Watt. At that current an 18650 cell of 2200 mAh will then be empty in about an hour.
For 50 Watt you need to use in the order of about (50 W / 7W ) = 7 cells. But since there will be conversion losses from converting 3.6 V to 5 V You might even need 8 or 9 cells to have some margin.
Also it is more efficient to use the cells not in parallel but in series and then use a buck converter to convert down the higher voltage to 5 V. That's for example how it is implemented in many laptops. Charging cells in series is more complex and definitely not something for a beginner. I would suggest that you use a ready-made battery pack which outputs 12 V for example.
The reason that upconverters that can output 5 V at 10 A is that the losses will be huge at such a current. If the upconverter was 100% efficient (which it is NOT) then at 3.6 V around 50 W/3.6 V = 14 A would need to flow. That's a lot of current, any extra series resistance will cause a massive voltage drop.
I would urge you to consider using a LED panel with a much lower power consumption as that will make things so much easier.
Answer: One way or another you want 5 V at 10 A.  That's 50 W.  Your batteries have to cough up that, plus some extra for the loss in the converter.  That's basic physics.  No amount of clever electronics can fix that.
Let's say you find a boost converter that is 85% efficient.  It will then need 59 W as input.  50 W of that will go to the output, and the remaining 9 W will heat the converter.
59 W is a lot to ask of a 18650 cell.  At 3.7 V, that would be 16 A.  And, the current goes up as the battery voltage runs down.  Check the datasheet of your battery.  That's either past the reasonable limit, or high enough that you will get significantly reduced energy per charge, and probably reduced lifetime.
Pop up a couple of levels and think about the larger problem.  You probably want a different way to address that altogether.  Or, realize that what you want to do is not feasible.
Answer: What about the min and max voltage ratings on the matrix display, whould it by any means be safe to run it on either 3.7v (single cell) or 7.4v (dual cell). If you're using standard LiPo cells the current draw is not going to be your problem when you do not need to scale the voltage (it's only 3C for the cell). (I'm drawing 120Amps out of a 4s LiPo pack everyday ;-) @80C).
One thing you have to keep in mind though is that LiPo batteries are unstable, so either too low or too high voltage can make them dangerous explosives. So use an existing protection circuit, or come up with some protection yourself.
Comment: Thank you all for your input. I decided to discontinue the project. As it is too ambiguous for my current knowledge


1TB ssd in late 2013 rMBP 2.4 i5

Question: I bought a 13" MacBook Pro with Retina display (Late 2013, 2.4GHz i5), and it only has 128GB storage. I found a 1 TB PCIe that will fit into the rig, but I'm a little confused from what I was reading on Apple. From what I gathered, it says that the 2.6GHz i5 is configurable up to 1TB, but says nothing about the 2.4GHz. Is this just how Apple sells it - they just don't give the option for 1TB on the 2.4 - or will this much storage not actually work on this computer?
Answer: According to the folks at iFixit, there aren't any compatible drives out yet.
Source: https://www.ifixit.com/Answers/View/181479/SSD+possible+%28%29+upgrade+on+ebay#answer181496

1TB ssd in late 2013 rMBP 2.4 i5


what's the meaning of "Per capita basis"?

Question: So yesterday Donald Trump said in a press conference that "areas of our country that have been hotspots have done much more testing on a per capita basis than South Korea."
I know that Per Capita means per person but what I don't understand is what's the meaning, when it's followed by basis like this statement here.
Answer: To compare on a "per capita" basis, means to use "per capita" figures for your comparison. You can similarly say

I will compare the drinks on a "sugar content" basis

This means I will use the sugar content figures to compare the drinks.
The claim is that for "Hotspots" like New York, the (number of tests in New York) ÷ (number of people in New York) is greater than (the number of tests in South Korea) ÷ (The number of people in South Korea).  I've no idea if that claim is true.
This compares New York with Korea on a "per capita" basis.
Comment: Thanks for your excellent explanation!


Is it possible to get a negative reputation?

Question: Is it possible to get a negative total reputation? I can't find any examples where this has happened.
Answer: No, this is not possible. From the Help Center article What is reputation? How do I earn (and lose) it?:

All users start with one reputation point, and reputation can never drop below 1.
Answer: It is impossible to obtain a negative reputation, as proved by this question from the Stack Exchange Meta site.


Changung the metadata of an NFT i own

Question: Is it possible for me to change the metadata of an nft that i own but am not the creator of?
Like can i change the image it is linked to and the attributes along with then freezing the metadata?
Answer: No. In the standard usecase (ERC721) ownership of a token doesn't give you any extra priviledges. Only the owner of the NFT can ever change the metadata of your NFT.
The weak point would be to 'hack' the centrallized service that hosts your metadata and change it on the same url, which is unlikely.

Changung the metadata of an NFT i own


What to use in place of gooseneck kettle?

Question: To make pour over coffee can I use a cup to pour the water on the grounds? How can I best approximate the proper water temperature? I do have a kettle to boil the water but a cup gives me more control in the process.
Answer: There are two important factors here: temperature and control.
Temperature
Temperature is probably the most important factor here. You don't want the temperature to be too low, when that's the case you won't be able to extract all that you want. You can easily ensure you're not using water that's too cold, either by pouring straight from the kettle (goose-neck or otherwise) or by preheating the pouring vessel (e.g. your pouring cup).
Control
Control is important for pour over brews, but it's not absolutely necessary. You can simply use a regular kettle to pour but you'll have less control over the flow rate (how fast water flows out) and where you irrigate the grounds.

So it's definitely possible to use a (pouring) cup instead of a goose-neck kettle, just make sure it's pre-heated.
Comment: even if the pouring cup is pre heated it is much thinner and will lose heat as fast as it heats up. just for temperature control, i would prefer using a kettle. gooseneck or not does not really matter in the first place.
Comment: @B.Kemmer it depends a lot on the material. If you have a porcelain pouring cup then it will certainly heat up. Doing so without preheating means some heat of the brew water is lost to the cup, whereas those losses are much less when the cup is preheated. Whether goose-neck is more beneficial depends on what you're comparing it to. If you have a broad spout on your kettle you will have trouble maintaining a steady pour for a few minutes. Of course you can try to compensate for that by pouring in intervals.


HTML entity in comment options

Question: I just wanted to upvote a comment in the Android App as I saw a HTML entity in the popup. See also my screenshot:
Comment: By the way it is a pain to ask questions with a screenshot it took me about 20 minutes to get that managed.
Answer: This had the same root as cause this bug from today, both have been fixed for next build. Thanks!

HTML entity in comment options