Splitting credit card number fields into four different inputs

Question: I have previously been using 4 fields for the credit card number, splitting up each set of 4 numbers to make it easier to enter.
I am now thinking about having one field, which inserts spaces after every set of numbers instead:

For the one with 4 fields, the cursor jumps to the next field automatically.
Which format is preferred? Or are there any other better alternatives?
I only accept Visa, Mastercard and Discovery, with 16 and 17 digits.
Comment: My bank's website has a 3-field input for sort code when setting up a bank transfer which auto-jumps to the next field once you've entered 2 digits.  When I noticed that I'd made a mistake in the previous field, I hit SHIFT+TAB, which moved the focus back to the previous field onkeydown, but when I _released_ the tab key, the site's onkeyup handler noticed there were two digits in that field and "helpfully" jumped the focus forward again!  Argh!  I had to find my mouse and click on the field.  Horrible.
Comment: Please please don't make it several boxes. I find this infuriating as I usually store my CC numbers in password database software which copy and pastes them in for me. This is totally broken when a website uses several boxes. Usually trying to paste it all into the first box.
Comment: What is wrong with a single entry field with no fanciness?
Comment: What if the credit card number was less than 16 characters (amex) or longer than 16 characters (can't remember the card type that does that)?
Comment: @nigel222 That's an argument for *displaying* the number with separators, *if* you expect the user to need to read it. But for inputting?
Comment: Possible duplicate of [What do you call this input element where a focus will automatically be transferred to next text field after being filled?](http://ux.stackexchange.com/questions/91706/what-do-you-call-this-input-element-where-a-focus-will-automatically-be-transfer)
Comment: be certain to use **A MONOSPACE FONT** for the 8 digits (or indeed, perhaps in fact behind the scenes have 8 separate slots, so you can totally control the spacing etc).  it's essentially to evenly-space the eight digits.
Comment: In addition to having less than 16 numbers, Amex cards also would require 3 fields instead of 4. You'd have to add extra code so that if the user was entering an amex number, the field count went to three, with a wider 2nd field. I'd forego the extra complexity and just leave it one single field.
Comment: It's worth mentioning that credit card numbers have a checksum. A good entry field should check this on the client side and tell the client they've made a typo.
Comment: Think of any interface which interferes with a basic task as a real-life acquaintance that desperately wants to be your friend so they awkwardly try to finish your sentences for you when you are speaking and they get it wrong or only marginally correct every time they open their mouth. You might be a nice person and finish whatever it was that you were trying to accomplish in their presence but surely you will loathe being in the presence of that person moving forward. Let the user finish speaking and **then** you can mention that letters are not accepted in the CC field.
Comment: @jpmc26 I don't think I have checked my CC# after typing it even once in my life. Either the whole combination (CC# + expiry date + CCV) is correct and the chances that I typed someone else's card number are insignificant, or it's incorrect and I'm going to find out very soon. And again, while I see how this could be an argument for *displaying* the CC# differently, I don't see why the *input* should be different.
Comment: I like what booking.com does. They have one text box, but the display inside that box changes depending on the type of card, so they will break it up into 4 blocks of 4 for VISA or MasterCard, but behave differently for e.g. Amex. You can paste one long number into it, and it looks really neat.
Comment: @DasBeasto looking at wikipedia (not a great source, granted) there's some canadian banks which issue 19 digit cards https://en.wikipedia.org/wiki/Payment_card_number  I posed the question more as a "has this been considered" statement, but admittedly in a recent project I worked on, the client didn't want to accept cards longer than 16 digits.
Comment: @gabe3886 It's possible that none of their payment networks have more than 16 digits (if they only support Visa, Mastercard, Amex, and Discover, for example); and they couldn't process payments for those bank cards anyway even if they could be entered in. For "ideal" user experience, I'd probably change the spaces around if the first digit is a "3" (Amex cards use different digit grouping)
Comment: @Najib Idrissi what's wrong with a string of 16 or 17 digits is the same reason they beak it up into shorter fields on the front of the card. Human beings find it hard to remember groups of more than five digits between looking at the source and reproducing them on the keyboard. Human beings find it even harder to check that two 16-digit strings are identical (ie, that there are no typing errors).
Comment: @SimonG. That's an invalid reason, even if you discount the notion that a technical reason shouldn't affect UI if it is not absolutely necessary.  The point is, that *reducing the likelihood* of the number entering the page file is not the same thing as *ensuring that it never does*.  If the specification requires the latter then you will need to take other steps anyway (e.g. only storing user data in non-pageable buffers) that render the suggestion unnecessary by always preventing the numbers entering the page file.
Comment: @ChrisH this sort of dynamic behavior heavily favors the more "lightweight" version with no boxes to be redrawn.
Comment: The bank I use offers one-time generation of credit cards on their website. Copy/pasting into a 4-box input field is much harder than a single field.
Comment: @Vality : My inclination was the opposite opinion.   Your reasoning swayed me.  Thank you for your input.
Comment: @daiscog Sounds like a nightmare gone bad.
Comment: I once tried to use my card in a payment system that had arbitrarily decided that it would impose a character limit on the cardholder's name field -- and that limit was shorter than the limit of my card issuer, which in my case meant shorter than the name. As a result, I simply couldn't pay through that system because my name is too long. What I'm trying to say is, there may be cases you haven't considered. So it's best to avoid reinventing or re-implementing rules for a system that already has its own rules and a way to enforce them. Just use a simple field and let the backend do its job.
Comment: @gabe3886 [This article](http://www.creditcardchaser.com/how-long-is-a-credit-card-number/) appears to state that it *can* go up to 19 digits but that none go over 16.
Comment: I like [jquery.payment](http://stripe.github.io/jquery.payment/example/) for this.
Comment: @Najib Idrissi see my full answer (just submitted) for my fuller opinion.
Comment: The current PCI-DSS requires that credit card numbers never appear in page files. This may appear irrelevant but if you break the payment card number into chunks to send then the number is less likely to appear as a contiguous memory block. I personally prefer to the user interface to offer a single box, but the resulting HTTP request to use chunks.
Comment: @NajibIdrissi It's hard to check the whole number at once. Splitting it up makes it easier to compare with the number on the physical card before submitting. Whether this small benefit outweighs the downsides is a discuss for answers, but it provides an obvious motivation for wanting a split up number.
Comment: @NajibIdrissi I am averse to experiencing an error when submitting payment information, so I always double check it. As I said, weighing the pros and cons and coming up with a solution are matters for an answer. I was just stating the motivation.
Comment: @Random832 is redrawing the boxes based on input "ideal" (assuming I've understood you correctly)?
Comment: @Random832 I agree
Comment: [This](https://news.androidout.com/wp-content/uploads/sites/3/sites/3/2014/05/paypal.png) is my favorite credit card entry field. Side steps the problem, and saves me having to enter my address.
Answer: I would generally always opt for the simplest solution. In this case, one single field for the user to type into.
With split fields, such as the 4-box one you propose it adds in an extra cognitive load to the user.

"Do I need to manually jump to each field?"
"Will the system do it for me?"
"What if I hit tab myself but the form automatically jumped - will it have jumped into the 3rd field instead...?"

All these extra questions - perhaps subconciously, perhaps more forefront in their minds - are not questions that would even be considered in a single field form.
Sure, 4-field options aid readability - so if the user entered their number wrong it's easier for them to re-read their entry to see what area they did wrong. But this can still be mitigated in a single field. Just as you showed above, you can render the user input with spaces in the single field.
Another consideration is mobile users. While it may well be simple on a desktop, a mobile has a keyboard it needs to open and close on entry of the field. Different devices and OS's behave differently, but it's quite likely that on the jump from field 1 to field 2 the keyboard will autoclose and autoopen, causing a jarring flash on screen, with the user possibly trying to click the 5th digit just as the keyboard closes, thereby moving the cursor into another area of the screen altogether, or just missing that digit from entry altogether.
This mobile issue is illustrated nicely on Baymard blog, where they also point out that mobile users tend to manually press into each field - something desktop users don't do as often.
Your proposal is a nice idea, but I think it falls into the category of 'overengineering'. Unless you're noticing significant user input errors on a single field I don't think you need to introduce an alternative. You could risk decreasing the usability instead of improving it.
Comment: @EshwarenManoharen  Just let them type the numbers, and ignore any other characters they type (including spaces) but render the output with spaces in the appropriate place.
Comment: @EshwarenManoharen just throwing this in here, no matter what you do in HTML/JS to allow only numbers, make sure that you validate the input server side, HTML/JS can be easily manipulated by the user.
Comment: Joined just to give this +1. I get very frustrated with UIs that auto-jump, such that when I tab I end up skipping an input box.
Comment: Bullet point 3 is a serious issue in lots of separated fields (phone numbers, social security numbers, credit card numbers); in "vanilla" forms, one gets used to pressing tab to jump to the next field, but when the "smart" form attempts to automatically move you, you wind up in the third field. The far more insidious (and related) "smart form" problem is the one that detects when a field has been completed and jumps you to the next field -- even when you click back into the field to make a correction.
Comment: Also, be prepared for people to type the whole number without looking at the screen. The easiest way to enter long numbers is to look at the card and type using the numeric pad.
Comment: @TomHart Hey, that's good advice.
Comment: @DoktorJ Exactly. Plus, you end up having to code for so many variances and interactions that the effort spent building these components is outweighs their usefulness. More code = more possible bugs / accessibility issues / compatibility issues / load speed etc.
Comment: I'll agree one single field is best **only** if it lets me type spaces as well as digits (and filters the spaces after submission without bothering me or saying that the number is invalid), or if it automagically displays spaces in the right places as I type (which means recognising from the first few digits whether it's Amex, Visa, or whatever, and adjusting the auto-space algorithm). The spaces make a **huge** difference to a human being trying to check that he typed his card number correctly.
Comment: @DoktorJ Totally, re point 3. Plus it breaks the "next" button most mobile keyboards have these days, and touch keyboards are already annoying enough without the form jumping around all over the place. Especially in landscape mode when you're peering at a web site through an infuriatingly tiny sliver of screen space, tracking where you are in a form by pure faith alone.
Comment: In addition to accepting spaces, also consider that the spaces make the input longer. I'm completely annoyed with my bank's IBAN entry field. IBANs are usually printed with spaces at well defined places. Now the input field doesn't accept spaces. Well, seems not too much of a problem, just copy/paste the IBAN and remove the spaces manually, right? Wrong. The programmer limited the size of the input field to the number of digits of the IBAN, and therefore the copy/paste will stop after that number of characters. Since those characters include pasted spaces, this means some digits are missing.
Comment: Speaking of cognitive load, should we highlight whether the numbers should be added with spaces or without the spaces?
Comment: Thanks, I think that works. At least in HTML, if you add type=number to the form, I think it won't show Space as well I think.
Comment: I've used single-field inputs for various types of info on web apps, and prefer them over multi-field inputs. You get quite extensive text-autoformatting Javascript libraries for the task, I've used [Igor Escobar's jQuery Mask Plugin](https://igorescobar.github.io/jQuery-Mask-Plugin/), others exist. It allows you to specify formatting characters like spaces, hyphens, braces etc. which can be typed, or are auto-inserted in the right position if omitted. Imagine doing e.g. a telno "+1 (12) 555 1234" in multifield inputs - much cleaner in a single field with an input mask. Con: scripting blocked.
Comment: Sadly, a typical implementation flaw I've found with most multi-field in the wild forms is being able to undo mistakes. Say I typo my credit card number 1234 5687 9012 3456 -- I try to click in "5687" and the JS magic kicks me to the end unless I have superhuman backspace reflexes, so I also :+1: for the "one field, allow spaces".
Comment: @nigel222 yes; it should allow spaces (or hyphens for that matter, because some people may enter it that way) and silently discard them in any validation scripts without modifying the displayed field.
Comment: I'm going to add one thing to this. Just eat the dashes or spaces server-side if you find somebody typed them in.
Answer: This answer and this answer cover some of the points nicely but for some reason nobody is discussing auto-fill support.
Don't use 4 separate fields.

First, it's annoying, a lot of those reasons are covered in the other answers.
Also, a CC number isn't four 4-digit numbers, it's a single long number. Some credit cards don't even have groups of four, in which case your four field input doesn't even make sense, for example:

The real one I want to add is some browsers give the option of filling out credit card info for you. Chrome, for example has this functionality, and Safari on iOS 8 will automatically add a camera-enabled "scan credit card" button to these fields if you craft them properly (see that article). And so the real "perfect" CC field from a UX perspective is a single field with the appropriate field name (like "Credit Card Number") and appropriate browser-specific trigger attributes (like autocomplete="cc-number" and id="cc_number").

Don't go trying to invent your own "convenient" input method for this. Stick to the same standard credit card number input methods that are already commonly in use (single field, appropriate name and attributes), because browser developers are already making an effort to improve the UX of these kinds of fields, so you let it be handled on the browser-side and give users something that they're familiar with instead of something inconvenient that also runs the risk of breaking all of the nice features their favorite browser normally gives them.
Comment: Great answer! I hope it gets its share of upvotes despite being late in the game. Here's mine.
Comment: When I make car payments, my browser (Chrome) tries to fill in my username in one of the credit card fields (split as four input boxes). This actually makes it *more* work than if it were one field. Developers really need to allow auto-fill to do its thing. Having one input field is the best choice. I'm also annoyed when my expiration date won't autofill because of some unusual jQuery plugin to select the month and year.
Comment: Great answer, to add to this, not all credit cards are 16 digits long; there are shorter and longer variants. I also wouldn't trust browser vendors to get it right, although you can certainly trust them more than a homegrown solution.

In my experience, it is better to avoid any prohibitive validation (validation that will not allow the user to continue) and let the payment gateway make the final decision.
Answer: As someone who happens to use virtual credit cards, I'm strongly in favour of a single field. Every time I want to pay, there is a new card number generated for me by the banking app, and it's very tedious to have to copy-paste four times instead of one. I'm assuming here that your form won't fill the 4 fields if I paste 16 digits in the first one. Will it?
Also, I have seen several 4-field designs which were incredibly hard to use. Sometimes pressing Backspace was required to come back to a field with a typo, in other cases Shift+Tab was required. Sometimes the field you jumped to had its text pre-selected or cleared, so it was basically impossible to predict how the form would behave without observing it after each key-press.
Just give me one field where I can paste a card number into, and let me use Backspace to fix any typos if I happen to type the number manually. Here's something that looks acceptable:
$('#test_form').on('keyup', function(e){
    var val = $(this).val();
    var newval = '';
    val = val.replace(/\s/g, '');
    for(var i=0; i < val.length; i++) {
        if(i%4 == 0 && i > 0) newval = newval.concat(' ');
        newval = newval.concat(val[i]);
    }
    $(this).val(newval);
})

Comment: @LightnessRacesinOrbit - Why is it an overreaction to not support a merchant that goes out of his way to make it harder for me to give him my credit card information? I'd also walk out of  a brick and mortar merchant if they made me swipe my card in 4 different credit card readers. If the merchant will autosplit a pasted number across whatever fields they want, I'm fine with that, but I don't want to have to paste the number somewhere else on the screen, then copy-and-paste each chunk individually (or type it manually)
Comment: Similarly, I keep my credit card number in my password manager, so I want to be able to copy-and-paste it into a single field. Several times I've abandoned a purchase when a  website expected me to break the number up into 4 digit chunks.
Comment: @LightnessRacesinOrbit I have done the same thing as Johnny many times myself (for different reasons, but everybody has their own valid peeves). It's not like there usually isn't 1000 other merchants to buy the same thing from these days. Philosophically, I don't support stores that make me do frustrating things in order to give them my money. Personally, I'm sick to death of crappy web design.
Comment: No, it's not an overreaction; the website is asking you to do extra, fiddly, error-prone work because they've made entering the number more complex than necessary. Frustration is a good reason to resent design. If only websites supported contactless payments ...
Comment: This functionality would piss me off immediately. I can think of more than one occasion in which I missed digits 5-8 of my credit card due to my cat attacking my face, child spilling juice on my back, or I get caught up swinging my sword at dragons. Anyways, the point is that now I must delete digits 9-16 if I wish to type in my missing digits or else your code will **put my cursor to the end of the text field on EVERY SINGLE KEYSTROKE**
Comment: @LightnessRacesinOrbit Nah, it's no trouble. When a business has to contend with so many competitors, like an online shop for example, if they aren't perfect, they lose. And I still get what I want, so no spite. On the other hand, if your payment form lets me take a picture of my credit card instead of typing it all in on my phone, you've just earned yourself a new repeat customer. In fact, I encourage *everybody* to take a stand against bad design, ha; only by working together can we defeat slide shows once and for all! Captaaaiiin Plannneettt!!!
Comment: Keyboard arrows are not working, Ctrl+A is not working. It does not look "acceptable" to me!
Comment: That's really cutting off your nose to spite your face, for something pretty trivial. But to each their own.
Comment: Bit of an overreaction isn't it Johnny?
Comment: Actually some fields do allow a 16 digit paste which fills in each of the 4 input boxes. Seen it more often than not, but your point is still valid
Comment: @MarkStewart I'm not an UI coder, but I assume this is because it's impossible to reposition the cursor in a text field those content was updated with JavaScript. At least I don't know a way to do it.
Comment: Credit card OCR! If you can get a solution past PCI-DSS that would be fantastic. Next best thing since Stripe.
Comment: @pjc50 Safari on iOS 8 [does it for web sites](https://www.paymentspring.com/blog/hacking-form-cardscan), and for Android and iOS apps there is https://www.card.io/, for free no less. The future is now, man. It's just a data entry method so maybe it's outside the scope of PCI DSS on its own.
Comment: @Francesco Do you have a better example? Certainly this question would benefit from a cleaner solution.
Comment: Usually when a phone number or credit card number field is split up into 3 or 4 fields, I often notice I made a typo and the web page's Javascript that does the "auto-tab" to the next field makes it nearly impossible to shift-tab to the prior field to make corrections.  Even clicking in the field with the typo often jumps the cursor to the next field as the Javascript sees four digits in the field with the typo, and jumps to the next field.  My wife can often hear me scream from the other room....
Answer: The simplest, if not necessarily the absolute best, solution is a single credit-card field that lets a user input any string of digits and spaces. It should be trivial for the server-side logic to strip the spaces out of the submitted string before checking whether the resulting string of digits is or is not a valid credit card number. If the user chooses to enter leading or trailing spaces or to break the digits in different places to what is on the card, so what?
Automagically inserting the spaces for the user may be slightly more user-friendly but is a lot more work.
Multiple fields with auto-tab from one to the next is OK, but if you take cards other than Mastercard/Visa then it is a lot of work to adjust the field lengths for the card type (e.g. 4,6,5,0 for Amex) on the fly (i.e in a browser-side script). On a card-company website that by definition only ever takes one sort of card, it's clear and easy. [Edit: OK-ish. Other answers indicate why it is a dis-benefit for some users ]
Refusing to let the user enter spaces is user-hostile. Allowing the user to enter spaces and then rejecting the (correct!) card number as invalid after submission is truly abominable, to the extent that I might refuse that retailer my custom at that point and instead buy from whoever was formerly my second choice.
Comment: Yes indeed. Requiring the user to remove the spaces from the credit card number is an example of lazy and harmful UX design. It is fine to store the credit card number without spaces, but requiring the user to perform the conversion by hand when the computer can easily do it is lazy. It is harmful because the spaces are there for a reason: to reduce data entry errors.
Comment: also, don't hard limit the length of the field to just 16 characters, if they paste a credit card number with spaces, some numbers are cut off, giving validation errors later
Comment: +1 for making the system do some of the work. (-1 for auto-tab.)
Comment: It is very bad for spaces not to be allowed for entry, yes it should be a single field. If you are a financial institution the first 4,6 or 7 numbers may denote a particular BIN, product, sub-product respectively and these may be more important to you under the covers so you yould define an object with these mapped. The operator does not need to know in most cases.  Also, despite PCI, some cards are swiped through a reader for entry, it is nice to dress the number.
Comment: This solution is by far the best. No possibility of confusion or unexpected reactions. No unexpected results from typing tab or space. Fully compatible with various browsers' autofill. The only thing I might add is putting the phrase "spaces optional" next to it.
Answer: Luke Wroblewski, a UX expert with great insights on building efficient forms, answered this question: use a single numeric input field (here's a video of how this works).

As you can see in the video above of Zachary's demo, a single input field is used to capture credit card number first. If the credit card number is invalid an error is displayed that prevents the user from moving forward. If the credit card number is valid, the generic credit card icon changes to reflect the type of card entered. This removes the need for a separate credit card "type" drop down or selector and reassures someone that their entry has been understood.
Once the credit card number is validated, it slides over to the left leaving only the last four trailing digits for reference and the next set of inputs appear in the mask: expiration date, CVV (security) code, and ZIP code. Since these are all numeric inputs, a 0-9 set of soft keys is all that is needed to keep people moving along on the keyboard.
Since the expiration date on a credit card can't be in the past or far future, the input mask one again helps keep people away from errors. Invalid months or years simply won't be accepted. After a valid expiration date has been added, Square's design features another excellent enhancement. The credit card icon changes to reveal where the CVV code is located on the specific card being used to pay. This small detail helps clue people in to what information is required next.
Because CVV and ZIP are also numeric entries, there's no reason to ever leave the dial-pad throughout the payment input process: no jumping between multiple form fields required. Zachary's also made sure that people can use their keyboard (tab and shift-tab) and mouse to move between the various parts of this payment input mask.
Comment: @KenMohnkern I don't tend to enjoy using forms where the placeholder is all that's there to tell me what data they expect. It makes it hard for me to review my input to see if the data is correct. Looking back at that credit card info in the link you shared, it takes a bit more contextual evaluation to determine which fields are which because there are no remaining visible labels.
Comment: @maxathousand - Absolutely right. Those labels need to move out of the input field.
Comment: Brad Frost has implemented [a single-field solution](http://bradfrost.com/blog/post/single-field-credit-card-input-pattern/) on [this donation site](http://foodbank.bradfrostweb.com/patternlab/v5/?p=organisms-footer). Try it out!
Answer: Please follow the advice of others and do not attempt to reinvent the wheel. Not unless you have read and understood the ISO standard ISO/IEC 7812 that governs Payment card numbers, which, by the way, range from 13 to 19 digits and usually (but not always - read the spec) include a check digit that you can use to validate the input.
Inserting spaces where there are none is almost always a bad idea. Think of all the possible combinations you will have to deal with; auto-filled, used to populate auto-fill. Pasted in with no spaces, pasted in with spaces, cut for use elsewhere (should the cut include the spaces?), typed in, edited, and at the end of the day, what is the problem you are trying to solve?
Answer: I think Card.js is my favorite user experience when it comes to adding cards. Not only it lets you type in very quickly (single fields etc.), they also show you where those fields are on your particular cards so you don't have to wonder where's expiration date or CVV. I recommend you check it out.
Comment: It's buggy if you modify the credit card number in the middle.
Comment: @Insane That, or people should stop trying to make fields "smart" when there's no need for them to be.  Give me a plain input field with nothing active attached to it (except maybe instant validation) and I'll be happy.
Comment: @Insane Delete a few characters and type some in the middle of the number. Sometimes the cursor jumps to the end of the input. Sometimes backspace doesn't delete the character before the cursor.
Comment: @Insane https://github.com/jessepollak/card/issues/257 sounds like the same issue and is 3 months old.
Comment: @CodesInChaos Guess the project needs a contributor
Comment: @CodesInChaos Maybe because I'm on mobile. You should submit these problems to the github so they can be fixed
Comment: @sgroves the "rest" is just the input field which is the part that's buggy. that's what we've been talking about.... we've said a normal input field would be fine. so..
Comment: **Do not use Card.js**! If you type the number incorrectly, you can't edit it in the middle. Try using backspace and then try typing numbers without clicking again.
Comment: @CodesInChaos How. I just tried and didn't notice any issues
Comment: @PeriataBreatta I more or less like the visual display, which doesn't affect the field at all. So really just keep the display and a normal plain input field except for the validation you talked about.
Comment: i'm not sure what the point of the visual display is—just seems distracting, slow, and buggy. the rest is nice though.
Answer: Please, for the love of God do not do the second option.
one HUGE UX flaw is (which the majority of sites do when implementing this shutter) you can't go back to edit the numbers previously, because it auto forces you to go to the next field since you filled out the data.
Let's not forget that creating multiple fields make it appear as though you are filling different bits of information. In your design, it makes it look like potentially the last field will be for the "security code".
Making it one field implies one chunk of numbers (but please do what you did in option one: indenting because that shows the exact same format as your card).
When filling out credit card details, you want to come close to what the design of the actual physical card is because users will then be able to scan the card and look up to add the information they have just scanned. Jumbling anything up will cause confusion and frustration (from my experience in working in the ecommerce world for years).
Answer: A minor extra point I don't believe is addressed elsewhere:  A single box is more accessible, especially on systems without a full suite of accessibility tools:

It scales if the window is zoomed (just zooming a browser window still leaves the cursor a thin line which can be hard to find - one pixel if I test on this page in firefox/windows)
Tabbing between fields behaves reasonably (don't forget shift-tab).
This may not be true any more, but some screen-readers used to struggle with unlabelled input boxes -- this may still be the case for speech input technologies, but I haven't used them.

I'm not saying you can't make an accessible (and standards-compliant) input with separate boxes, but a single box is easier for you and users who need (or want) atypical interfaces.
Answer: My solution in the end, was to use one field. Then every 4 digits, it adds a space. Therefore it creates less potential confusion, yet also allows you to clearly view the credit card numbers, in the same format as the card.
The potential issues that arose are:

Different number of credit card numbers, e.g. 16 or 17
When deleting numbers, it must also delete the spaces when necessary
What to do when use clicks on a number and adds or deletes, how will
that affect spacing?
Typing too fast - javascript can not always react fast enough

If you can get around these issues, then I believe this the most intuitive.
I have created a form here https://jsfiddle.net/9apu6ux3/ as you can see it splits up the numbers nicely, but is difficult to make bullet proof.
Comment: Sorry, but I struggle to get around the issues when what I type is not what I get, but only sometimes. Inserting a space if, but only if I typed the fourth digit slowly enough is disconcerting.  Consider reformatting on loss of focus instead.
Comment: Not all credit card companies separate their credit card numbers into 4-digit blocks. This does not seem like a good solution to me.
Comment: You might be introducing confusion to people with 17 digit cards who see the last digit hanging out by itself and not matching their card. Not everyone knows that the spaces between digits are meaningless.
Comment: When your form is auto-filled (or pasted into), spaces are added at the end, but that's minor. What's worse is when you try to navigate the filled form with arrow keys, it keeps adding those spaces.
Comment: I have made another jsfiddle which I like better, and put into my answer. Mind to take a look?
Comment: sure happy to take a look
Comment: Do not split numbers into blocks of 4. That's not how it looks on my AMEX!
Comment: perhaps the single most important issue is to use a Monospace font.


Would Ryuk have died if he had killed the SPK?

Question: In the manga, Light begs Ryuk, to kill everyone in that room. So let's say, Ryuk would have killed the Japanese Task Force and the SPK. Would Ryuk die after he killed them?
Comment: Possibly yes, but I don't remember the DN rule about killing for a human well enough to give an answer atm.
Answer: Rule LVIII:
1) By manipulating the death of a human that has influence over another human's life, that human's original life span can sometimes be lengthened.
2) If a god of death intentionally does the above manipulation to effectively lengthen a human's life span, the god of death will die, but even if a human does the same, the human will not die.
This seems pretty explicit to me.  Note that this seems to refer to killing with the death note but if a god of death kills by any other means he is given an "Extreme Level" punishment and then is executed.
What's love got to do with it? Nothing
Comment: So he would have died only if he had intended to lengthen Light's lifespan?
Comment: Yes... but that is why light asked him to kill them.  If he killed them for fun after light died, he would not die but that would serve no purpose beyond just randomly slaughtering anyone.
Answer: Doubt it. Ryuk did not love light (which is the requirement for dying).  Ryuk was just hanging around for the entertainment. Even if he killed everyone in the room it was probably to extend his entertainment. He however would never do this because he was impartial to light and had explained this to him in the very beginning. Whenever he did help light it was because he didn't want to be further bothered.  In this case saving light would have caused him more work.
Comment: *Love is blind.* Rem suggests when talking to Misa that Shinigami know full well what happens to them if they lengthen a human's lifespan by preventing their death. since you can't bargain with a Shinigami to have them risk their existence to save you Love is about the only think that will make them risk it. Love isn't a requirement per say but more of a reason to explain the action
Comment: Maybe but the rule comes down to if he's doing to help light or doing it for other reasons. If you look at it as just because he killed them light gets inadvertently helped that would apply basically to a lot of scenarios worldwide where shinigami killing someone may accidentally help someone else out.  It comes down more to you're doing it for the sole goal of helping a person out rather than other motives like your own entertainment or extending your life.
Comment: well if ryuk would have killed the spk and the task force, he could have watched how light would make his ''new world.''
Comment: The wording of the rule is "an individual he favors".  Even if it is just for his fun, it would mean he favors Light for his ability to entertain him.
Comment: Doesn't this answer goes against the Question? It was asked if he would die SUPPOSED he DID killed them. Not if he would do it.
Comment: To clarify a comment i made here earlier which is different from my answer, another rule than the one I quoted specifically refers to them dying of they use it to save someone they "favor". The more general rule obviously superceeds in cases where that is not the case but the punishment is identical.


What is the basic structure of British Politics?

Question: This is obviously an extremely broad (but answerable!) question, and I honestly don't know where to start and have no knowledge whatsoever about the topic. Basically I would like to know how the political system is structured and how the government operates at the highest levels.
Comment: Are you asking for good readings on British Politics? If so look at "Good Morning Prime Minister" :)
Comment: In addition, the site FAQ says that, "If you can imagine an entire book that answers your question, you're asking too much." I suspect this may be true of this question.
Comment: Are you asking for how things are now? (as your question implies?) or how things were back in the past? You've tagged this "british-empire", a term which isn't in use in the UK now, which implies you're interested in the past. So which is it?
Comment: [Wikipedia](http://en.wikipedia.org/wiki/Politics_of_the_United_Kingdom) has a good amount of detail. But is this really a history question? Perhaps it could be rephrased to make it more like one?
Comment: Ahem. How about politics of Great Britain?
Comment: Officially a constitutional monarchy and cabinet government, reality a president and murdoch = same as USA
Comment: What period are you looking for?  The basic structure of British politics has changed greatly over time.
Comment: I think that one feature that the current (quite excellent) answers are missing concerns how the government falls, and the entire issue of a "Vote of Confidence"
Answer: My answer is confined to the current structure of the United Kingdom.
I recommend you watch this short five minute explanation of all the countries/territories that are governed by the United Kingdom, and the Crown.
Since you are referring to "British" politics I am assuming that you are talking about the United Kingdom which comprises four separate yet equal countries: England, Scotland, Wales, and Northern Ireland. Technically, the monarch, Queen Elizabeth II, is the head of state in the United Kingdom (and in 16 of the Commonwealth nations), but in reality the monarch exercises very little power and instead the power rests in the Parliament of the United Kingdom. However, for local matters concerning Scotland, Wales and Northern Ireland they have Devolved Parliaments or Assemblies that control what goes on in their respective countries. For example, issues related to health care and education may reside within the purview of the Scottish Parliament, the Welsh Assembly, or the Northern Ireland Assembly, not with the United Kingdom Parliament (although the latter could in theory overrule the others if it so desired).
The United Kingdom Parliament is composed of three parts: the House of Commons, the House of Lords, and the Sovereign.
The House of Commons consists of MPs (Members of Parliament) that are elected from across the whole of the United Kingdom. The Prime Minister of the United Kingdom is drawn from the House of Commons and is historically supposed to be able to lead the majority of MPs which is why it is often the leader of one of the two major political parties (see e.g. the Hollywood take on this phenomenon The Iron Lady). The Prime Minister also appoints and dismisses all members of the Cabinet which holds most of the power within the government.
The House of Lords consists of Lords Spiritual and the Lords Temporal. The Lords Spiritual consist of the most senior Church of England clergy: the two Archbishops (York and Canterbury), and about forty other Bishops. The Lords Temporal are mostly life peers (meaning they are a Lord for their lifetime), with a small number of hereditary peers (meaning their office is passed down by blood).
The Sovereign is the Crown in this case, Queen Elizabeth II, and only is relevant for symbolic political events, etc. Technically, the Sovereign has to agree to the passing of laws, but that consent is assumed unless the Queen explicitly states otherwise.
The House of Commmons, House of Lords, Prime Minister, and the Cabinet (with the Cabinet being "most powerful") make up the governing structure of "British" politics. These parts of the government work together to pass bills which follow the following process:

Basically, a Bill pass must through several stages in both Houses of Parliament to become a law.
  These stages take place in both Houses:
First reading (introduction of the Bill without debate)
Second reading (general debate)
Committee stage (detailed examination, debate and amendments - in the House of Commons this stage takes place in a Public Bill Committee)
Report stage (opportunity for further amendments)
Third reading (final chance for debate; amendments are possible in the Lords)
source: How laws are made in Parliament

So that is the basic gist of how the United Kingdom government is structured, and how they pass legislation. Most of the matters covered by the United Kingdom Parliament are related to taxation, defense, and other matters of significance that affect all of the United Kingdom countries.
Comment: Excellent answer. Furthermore, there are three main political parties. Labour ("Left wing" or Socialist), Conservatives ("Right Wing" or Tory) and Liberal Democrat (who knows these days). Usually control flips between Labour and the Conservatives. MPS are elected by the first past the post systems and the party able to secure a majority (50%+) of the MPS can govern. So it is possible to be in power with a minority of the votes.
Comment: "The Lords Spiritual are Archbishops from around the countries." Not quite. Lords Spiritual are only from England. Wales and Northern Ireland have both "disestablished" their respective churches and the Church of Scotland, whilst established, does not participate in the Lords.
Comment: @AndrewTurvey thank you. I got the information from the Parliament website, but it appears I misread the information. I edited my answer. Thanks.
Comment: The Liberal Democrat would be the traditional 'liberal' party, i.e. pro-capitalism/free trade but also pro-personal liberty (i.e. not likely to be banning pornography or setting up religious schools).
Comment: @Rory - although many of their policies are now to the left of NewLabour, but they are in a coalition with the conservatives So James' "Who Knows" is a reasonable political definition
Answer: @ihtknot's answer is pretty good ( What is the basic structure of British Politics? ), however I'd just add that although the UK Parliament is made up of House of Commons, House of Lords and Monarch, in reality the Lords and Monarch are subservient to the House of Commons. The Monarch must sign all laws that have been passed by Parliament (i.e. there's no veto like in the US system), and the House of Lords by convention does not block laws that are part of the winning parties political manifesto, and the Lords can only block a law twice in a row. (i.e. if the Commons passes a bill to the Lords three times in 3 consequentive years, then the on the third time the Lords cannot block it, but it must be passed. This is how controversional matters like a ban on fox hunting got through).
Since the UK has no written constitution, all of this has sorta evolved over ~ 400 years, and it's sorta not fallen over yet.
Another difference with the UK (and say US or (I think) German system) is the 'party whip'. Basically political parties have a lot of control over what their members can vote on. By default, when MPs go to vote, they must vote along party lines. This means voting is mostly a rubber stamp of what the central party / cabinet wants. If there is a controversial matter, then a free vote is allowed, where MPs can vote either way.
If you are interested in British politics, I'd caution you that 'The Iron Lady', while a good film, does not give a full picture of 1980s UK politics/history. The UK miners strike was barely mentioned and that had a massive impact on UK politics and industry, and the troubles in Northern Ireland is low key aswell. I'd recommend augmenting 'The Iron Lady' with 'Billie Elliot' (a young boy who wants to do ballet during the miners' strike) and something like 'Hunger' (for a raw look at northern ireland prisoners).
Comment: To be pedantic, the monarch _can_ decline to sign a Bill into law. But doing so would almost certainly bring us quite quickly to a republic; it was last done by [Queen Anne](http://en.wikipedia.org/wiki/Anne,_Queen_of_Great_Britain), if I recall correctly
Comment: Don't forget that if a policy is too unpopular, or the whips ride too roughshod over MPs they can rebel - this has occurred in the past, and can bring down a government.
Comment: The US House of Representatives have whips too ( http://en.wikipedia.org/wiki/Leaders_of_the_United_States_House_of_Representatives#Party_whips ). Also, there's been a lot of grousing lately that the House and Senate (particularly the Republicans) have been starting to look more and more like the British parliment where pretty much the entire party votes in lockstep. See http://www.washingtonindependentreviewofbooks.com/bookreview/its-even-worse-than-it-looks-how-the-american-constitutional-system-collided-with-the-new-politics-of-extremism/


How to give away money in GTA V Online?

Question: I just got GTA yesterday, and I held up a store. When I came outside someone gave me a ride away. Is there a way for me to pay him for helping me?
Comment: There's an option in the context menu which is something along the lines of "Share cash from last job". I'm sure you'll get a more detailed answer soon.
Answer: Go to the interaction menu (M), select Inventory -> Cash -> Share Cash from Last Job. There you can see how much you earnt and which percentage you want to give to any other online players in your session.
Comment: For robbing stores at gas stations in freemode, yes, it definitely works.
Comment: That works for jobs and missions - but does it work for stealing from a gas station in free mode?
Answer: There is a different way but it requires a lot of money, more than you're gonna share:
Go to LS Customs pick a car there and tune it. DON'T place insurance on it. Then, go to sell the car to see how much its worth, don't sell it, go to the closest mission, join the mission with your friend and leave (you have to host). The car will then spawn on you again so your friend can take it and sell it.

How to give away money in GTA V Online?


How do I accept a file via Bluetooth?

Question: It's a bit strange to ask, but the situation is: I can easily send from my laptop with elementary OS files via Bluetooth, but I do not understand how to accept a file. The system notifies me that a device is trying to send me a file. I remember with ubuntu with GNOME it suffices to click "accept" to the notification itself, but on eOS any choiche does not appear and clicking on it leads to nothing. So: what to do?
Answer: I have managed to fix this in elementaryOS 5 (Juno). You might be able to do this on lower versions as well:

Pair the device with your computer using the default Bluetooth settings in the control panel (I assume that you have already done this).
Install blueman: sudo apt-get install blueman
Open blueman services: blueman-services
A window should open, here you can select "Transfers" -> "Accept incoming files from trusted devices".

When you tick that box, it will work. I am not sure if you can remove blueman afterwards.
Answer: In addition to what Pieter shared in his answer, I had to take the following additional steps before I could receive files from a Windows 10 laptop:

After installing blueman, restart the computer and open the applet (It might be possible to run the applet without restarting: blueman-applet).
Click on the applet icon and select "Devices...".
Select the Bluetooth device that you want to receive files from.
Make it trusted, either from the toolbar button, or from its context menu.

The crux is probably that blueman differentiates between trusted devices and connected but untrusted devices. It will automatically accept files only from trusted devices. It seems like there is no way to accept a file transfer from the gala notification, nor is there any way to mark a device as trusted except within blueman.
EDIT: I am on elementary OS 5.1 Hera, blueman 2.0.5-1ubuntu1
Answer: Im on Odin and tried to transfer files from my phone but unsuccessfully, just installed blueman and it work perfectly now ty

How do I accept a file via Bluetooth?


Low voltage cutoff circuit

Question: I'm powering an attiny45 from a lithium ion battery; using these batteries the voltage cannot get below 3volts or it will damage the cell. How should I go about cutting the voltage out? Software, or hardware? I'm not sure!?
Answer: Holding the MCU in reset is both a decent way to reduce its current consumption to almost nothing as well as indicate that the battery is low. Unfortunately most ATtinys have 2.7V as their closest BOR value so you will require an external voltage monitor if that is not high enough for your purposes.
Answer: You will want to add a chip such as a TCM809T to your design. This chip will monitor the VCC line for being between 3.04 and 3.11 volts. When below that range an output pin will be driven low. You can use the output signal to control a FET voltage switch to cut off the load from the battery.

Low voltage cutoff circuit


What did God see in Noah, that earned his grace? As I can find no reference to what he did, or how he lived in the scriptures.

Question: As stated in Genesis 6:8 (kjv) But Noah found grace in the eyes of the LORD.
Comment: I find it interesting that Noah is not the only person in Genesis who "walked with God". It says nothing unique re: Enoch. However, both he and Noah had their lives saved.  Enoch "walked with God" (Gen 5:24) and had his life saved permanently  Noah "walked with God" (Gen 6:10) and had his life saved, temporarily.
Answer: It is answered in the next verse, as well as the first verse of Genesis 7:
Gen. 6:9:

9 These are the generations of Noah. Noah was a just man and perfect in his generations, and Noah walked with God.

Gen. 7:1:

1 And Yahveh said to Noah, "Come, you and all your house into the ark, for I have seen you righteous before Me in this generation."
Answer: He also was a "preacher."

2 Pet. 2:5 Noah, the eighth person spared, a PREACHER of righteousness,..

This would be pleasing to God.
Answer: We cannot be sure if Noah was the only righteous man left, but still:
The sons of God saw that the daughters of mankind were beautiful, and they took any they chose as wives for themselves. And the Lord said, "My Spirit will not remain with mankind forever, because they are corrupt. Their days will be 120 years." The Nephilim were on the earth both in those days and afterward, when the sons of God came to the daughters of mankind, who bore children to them. They were the powerful men of old, the famous men. When the Lord saw that man's wickedness was widespread on the earth and that every scheme his mind thought of was nothing but evil all the time,
Genesis 6:2-5 Holman Christian Standard Bible

All peoples' lives were eventually shortened, not just some who were wicked

Now the earth was corrupt in God's sight, and the earth was filled with wickedness. God saw how corrupt the earth was, for every creature had corrupted its way on the earth.
Genesis 6:11-12 Holman Christian Standard Bible
Translations of Genesis 6:9
This is the history of the generations of Noah. Noah was a just and righteous man, blameless in his [evil] generation; Noah walked [in habitual fellowship] with God.
Amplified Bible, Classic Version
These are the generations of Noah: Noah was a just man and perfect in his generations, and Noah walked with God.
King James Version

"Perfect in his generations" likely meant that there was no "sons of God" pollution in his line

This is the family history [2:4] of Noah. Noah was a ·good [righteous; just] man, the most ·innocent [blameless; Job 1:1] man of his ·time [generation], and he walked with God [5:24].
Expanded Bible

The Job 1:1 reference for "blameless" is: that man was perfect and upright, and one that feared God, and eschewed evil -KJV

So it is likely that Noah's "Walked with God" relationship, blameless and righteous character, and genetic history free of the evil that plagued others caused him to find (not earn) grace in God's eyes.
There is a very thorough analysis of this idea at

https://enduringword.com/bible-commentary/genesis-6/
Comment: Welcome to Bible Hermeneutics and thank you for your contribution. When you get a chance, please take the [tour] to understand how the site works and [how it is different than others](https://hermeneutics.meta.stackexchange.com/questions/653/how-can-we-educate-new-users-about-our-site-distinctives/803#803).
Answer: I think the bible is clear; Noah pleased God because, just like Abraham, he believed God and it was accounted to him for righteousness. Without faith, it is impossible to please Him.
Hebrews 11:6-7 (KJV)

6 But without faith it is impossible to please him: for he that cometh
  to God must believe that he is, and that he is a rewarder of them that
  diligently seek him. 7 By faith Noah, being warned of God of things
  not seen as yet, moved with fear, prepared an ark to the saving of his
  house; by the which he condemned the world, and became heir of the
  righteousness which is by faith.
Answer: other people "feared the Lord and escheweth evil" perhaps this is one way to describe it.
Belief preceeding obedience.  noah believed God and did what he instructed
Answer: Although there is no written text that says Murder is wrong but there are text that indicates there are rules/laws established.

He told him, "You may eat the fruit of any tree in the garden, Genesis 2:16 GNT (permission given)

Then the Lord said, "Why have you done this terrible thing? Your brother's blood is crying out to me from the ground, like a voice calling for revenge. Genesis 4:10 GNT (murder is wrong)

but everyone else was evil in God's sight, and violence had spread everywhere. Genesis 6:11 GNT (all violent acts is wrong)

Now you can eat them, as well as green plants; I give them all to you for food. Genesis 9:3 GNT (cant kill animals for food)

But because the king had taken Sarai, the Lord sent terrible diseases on him and on the people of his palace. Genesis 12:17 GNT (do not take wife belongs to others: no adultery)

and there are some other such examples (further reading) that indicates there are already laws in place to govern how human beings treats each others. After that Noah teaches his children (some follows some not) and their children passes on...
So it is clear that Noah did follow certain sets of laws that God see him as Righteous. If without such laws, there isnt a guide to differentiate who is righteous, who is evil.


Betting the flop with air

Question: I've been studying NL holdem for a while and feel like I can grasp the basic concepts pretty well, but looking at GTO solver play post flop really makes me wonder. When I'm in a spot where I completely missed the flop, I have no idea if I should be betting as a bluff or not. I understand late position is helpful, but what are the other factors to consider in such a situation? Stack sizes?
Answer: You should try to think less about the exact hand you have in a particular spot, and think more about the range of hands you can have. E.g. If you are the pre-flop raiser, that means you have a range that includes all the best starting hands: AA, KK, QQ, AK, AQ, etc as well as all the other hands you play, whereas if you just called a raise pre-flop, it's hard for you to have a those strong hands (otherwise you'd have raised). That means that flop that contains high cards favor the pre-flop raiser's range, which means that the pre-flop raiser gets to be very aggressive on these boards. So for instance, say you raise from middle position with 77, and the button calls you. The flop comes AK8. Should you bet? You have an underpair to the flop, which means that if this board hit your opponent in any way, you're behind. But that doesn't matter: You should always continuation bet in this spot, because the flop massively favors your range. Your opponent can't really have AA, KK, AK or even AQ here, because they would have raised those pre-flop, but you can have them.
Now suppose you raise pre-flop from middle position, but this time the flop comes 8c7c5s. What should you do on this flop? The answer is that you should check most of your range, because the flop is much better for the pre-flop caller's range. All those high card hands that you can have that the pre-flop caller is not supposed to have, are now a liability, because while they may very well still be the best hand, you really don't want to bet and face a potential raise with any of them on this board.
Now consider the situation where you raise pre-flop, and the big blind calls you, meaning you will have position on them post-flop. Say the board comes 8c7c6s like above, and the big blind checks to you (as they always should). Should you bet or check behind? Now it becomes a bit more complicated. The answer is that you should continuation bet selectively with a polarized range, i.e. a range that consists of your strongest hands (over-pairs, sets, two-pair), and you weakest draws (low flushes, belly-buster straight draws, back-door flush draws), and you should bet big (close to the size of the pot). With the your medium strength hands (e.g. 98, A7) and strong draws (open-ended straight draws to the nut straight, ace high flush draws, combi-draws, pair + straight or flush draw), as well as you completely hopeless hands (i.e. hands that missed completely and have no chance of improving to the nuts, like 22, A3) you should check behind, because you don't want to have to face a raise with any of them.
Answer:
what are the other factors to consider

Short answer: everything.
This play is common, so common it has a phrase to describe it; Follow up bet. For many players, it is almost common to do a follow up bet every time they raise, and often players will make a bet when it is checked to them rather or not they raised before the flop.
This is just bluffing and bluffing is often good to do. I personally watch closely when I am in a hand. If it looks good to take the pot with a bet, don't care what my hand is I take a shot. And then I watch more, to figure out if I need to shoot again or cease fire or give him a river to miss his draw. The simplest way I can describe that thought process is that you put the player on the range of hands they have and make a judgement about how likely they are to lay down the hand.
When your doing a bluff, you also need to be watching your own tells. I was once called on a stone bluff by a guy with jack high and lost. I thought the guy was a moron to call the mighty me with jack high, but I am sure there were tells there that gave me away.
Comment: The normal term is "continuation bet", not "follow up bet".
Comment: @SteveBennett thanks for the useless feedback. both terms have been widely used and mean the same thing.
Comment: Heh, if you google "follow up bet", this answer is the second hit. "Follow-up bet" is simply not the correct term for an automatic bet on the flop.

Betting the flop with air


How to detail conference presentation of my work that was given by someone else on CV?

Question: Recently some work of mine was presented at a prestigious conference by the second author on the forthcoming journal article. On the write-up submitted to the conference I was listed as first author, but was unable to attend for personal reasons. How should I list this achievement on my resume whilst still acknowledging the roles played by each author?
Answer: A CS view on this - other fields (even other subfields within CS?) may have different conventions:
It is irrelevant who gave the talk. It may be the first author, it may be one of the other authors, it may be someone else entirely (e.g. if none of the authors could come to the conference for some reason).
During the presentation, it is important for the audience to know who is presenting, which is why in the presentation slides, the name of the person may be highlighted. However, that is not so much to assume much credit for the work, but to give the audience an indication of who they are talking to; how to address the person in the case of questions, and just to associate the right name with the right face. In a well-functioning team of several authors, chances are that the slides were not done by a single person, anyway, so the slides themselves are again a group product of several or all of the authors.
Bear in mind that, while a publication on a conference is generally assumed to mean that one of the authors presented the paper, extraordinary specifics of how the presentations were done are generally not listed anywhere, neither in bibliographies, nor in CVs. Additional people who presented, but were not authors, never appear there, nor do hints about "exotic" presentation methods (given that there is tremendous variation in what a "poster presentation" means, depending on the conference, I can well imagine that for some conferences, a "paper presentation" is not necessarily the traditional stage talk + slides).
Such details might be slightly interesting, but at the same time, it would just be too cumbersome to keep track of all of them, so lastly, the core of your work is the paper/article that gets included in the proceedings, and that is what you refer to.
Comment: _It is irrelevant who gave the talk._ — Unless you are on the postdoc/job market and you want to emphasize that you've given several conference talks.


Physics Courses in Undergrad to Apply for Physics Grad Program

Question: I am a sophomore physics student with an interest in studying applied physics or engineering in graduate school. I will take as many applied physics courses as I can in undergrad (and CS courses), but was curious as to what opinions most physics grad programs have toward Chemistry courses in undergrad. I have a strong feeling that Chemistry (2 semesters of it) would look great, but it would be hard for me to squeeze them in to my schedule. I know that it will vary by grad school, so I am wondering if anyone has a general rule of thumb when it comes to this?
Comment: It might depend a bit on what parts of Physics you want to focus on. It is a pretty broad field.  Any of your current physics professors could offer advice, of course.
Comment: Is this in the US?
Comment: Yes. In the US.
Comment: It's definitely good to make long term plans and think about what you want to do in the future. But your question strikes me as premature optimizing. As a second year student you should focus on *learning* rather than what a graduate application committee thinks. Take courses in which you think you'll learn something useful! That'll pay off handsomely on the long run..
Comment: In addition, if given a choice grad school admissions actually strongly prefer students who took courses because they were interested in the material rather than trying to optimize their grad school chances. In reality, that's difficult to tell apart but just to illustrate the point: sometimes one can e.g. see that a student's research projects were simply done for the purpose of CV padding. That's a huge red flag and often disqualifying. I guess what I'm trying to say is taking courses you're interested in doesn't actually lower your grad school chances. Go ahead and "follow your heart" ;-)
Answer: Taking chemistry courses is good, but there is no need to remove physics courses from your schedule to add chemistry courses.


Why would one aim off when navigating with a map and compass?

Question: Sometimes while navigating with map and compass, the advice is to aim off i.e. to aim either to the left or right of the intended destination, as opposed to straight for it.
Why and when would one want to do this?
Answer: The reason is that you could miss your destination and hit a trail and know that you are almost there, but not know which way to turn.

So if you were to go straight for the destination, and because of Murphy or errors or whatever and you ended up at either Point A or Point B, you wouldn't be certain of which way to turn to reach the trail intersection.
If on the other hand you had gone for Point B in the first place, you would know that when you got there, you needed to turn left. That is why one would aim off.
This works well when you are going for  a single point on a well defined line like a trail or stream.
Note:
The error is exaggerated for artistic purposes, but if you were to go for the destination straight off, your margin on either side is how far you would be able to see the destination from.
On the other hand, while aiming for Point B, so long as one doesn't end up to the left of the destination, one is fine, and that is a much wider margin or error.
Answer: In addition to the case described by Charlie (and to show that I also can make drawings in Paint), there is the case where you want a stopping line to know when you are going too far. This is mainly useful when you are aiming for the end of a feature. The drawing below is with a river bend that you try to reach, but the same principle works when aiming for the end of a trail, the end of a fence, a turn in a path etc.

Obviously, the shortest way is the green line. But what happens if you deviate slightly from it to the left or the right? To the right is not an issue, but if you unknowingly deviate to the left you will end up in the situation of the red line. You should be more or less at your destination, but have no idea if you are too far or should continue a bit further. You are lost.
To avoid ending up lost, you will usually, on purpose, aim a bit to the right and follow the yellow line. It is a bit longer than the optimal green line, but you are sure that you will end up at the river. And once you hit the river you know that you should follow it a little to the left to end up at your destination. It is a bit longer than the green line, but at least you know that you will not end up in the hopeless case of the red line.
Answer: I was in the Army Infantry in the '90s when we still used maps and compasses to get through the woods.
People have a tendency to veer off to the side of the hand holding the compass when they are land navigating, especially at night. You could try to compensate by switching which hand you are holding the compass with periodically during that leg of the trip. You could try keep in mind that you veer off and try to compensate. Or, you can just assume it will happen and aim a few degrees opposite of the direction you know you veer.
This mostly happens with "dead reckoning" which means you are using your compass and not some distant landmark to stay on your azimuth.
There are times you can aim a few degrees off during the day when you are walking towards a landmark far away. For instance, if, after looking at your map, you see that your destination is 35 degrees and 650 meters away from you, you could try to keep a pace count and try to stay on azimuth and hope you have kept track of these two things properly and your target will be right where you think it should be. Another method is to see if there is something close to your target (but maybe a few degrees left or right of it) that you can see from your starting point that is also on your map (hill top, tall church, road intersection.) You can easily find and go to that reference. Once you are there you have a much shorter distance to travel to get to your actual target. This gives you a better chance of finding it b/c your pace count is more accurate the shorter distance you go and you will not have as much of an opportunity to veer off your azimuth.
Answer: Navigation - be it either over land or sea - is governed by non-Euclidean geometry, which means dealing with a sphere instead of a plane. This also means that shortest path between two points on a sphere will never be straight line (unless you can dig really fast). This shortest route is called orthodrome.
When bearing is designated by compass only we pass every meridian at a same angle (as all meridians converge on the poles), which means we're traveling along the loxodrome (except for bearings due north or south or when travelling along the equator).
Aiming slightly to the either side of the compass-designated bearing (which side obviously depends on which direction you're travelling to and which hemisphere you're on, I think) allows to compensate for the loxodrome and to come closer to the orthdrome route, which means you have to cover less distance. The longer the distance, the bigger the difference.
As obviously, this one starts to matter at distances greater than 6 km, which is when curvature of the Earth's surface starts to become noticeable. However, maritime navigation says that going over orthodrome gives benefits over the loxodrome on the distances over 500 NM.
Below images show you what the difference is:
Comment: Explaining the differences between *orthodrome* and *loxodrome* is important in global cartography or navigation. However, it has nothing to do with the current question, which is about *local* navigation. (This sort of answer might appear in http://gis.stackexchange.com)
Comment: @jpmc26 I would walk 500 nanometers and I would walk 500 more to be the one that walked a micrometer to fall down at your door.
Comment: When I'm walking to a place and wind up 500 nanometers from the destination, I usually consider myself to have arrived. ;-)
Comment: In fact, for me it would be perfectly acceptable to  ask a very similar question about long distance navigation. Sailing is on topic on the website, so if you frame it that way it be on topic and you could just copy this answer. Though I feel that the answer should mention the Mercator projection. The fact that a loxodrome is a straight line on a Mercator map is why this projection grew so popular, despite its obvious shortcomings.
Comment: 500 nanometers?! lol. Perhaps a [less ambiguous abbreviation](https://en.wikipedia.org/wiki/Nautical_mile#Unit_symbol) is in order?
Comment: The question is very generic, so this answer is ok in my opinion. Just the orienteering tag does not justify disallowing answers. A separate question about this issue in specific would still be a good idea as well.
Answer: The most common reason to aim off is because there's an obstacle in your way.  This is one of many reasons why it's important to keep an accurate pace count, and know the distance to your next waypoint.  It's also very desirable if you have a good backstop past your destination, such as a road, river, tree line, etc.  You can then aim off to right or left, hit your backstop and travel along your backstop.  Depending on the angle of the backstop to your destination and aimed off line of travel, you can tell if you're to the left or right of your destination by your pace count.  If your pace count is longer than to your destination, you are the far side.  If your pace count to the backstop is less than to your destination, you are on the close side.
Comment: Hi Todd, welcome. Before answering please read existing answers, as well as our [about] and [answer] pages so you are a) not repeating something already posted, and b) meeting site quality requirements. Thanks.


How many Newtons are in a kg exactly?

Question: I understand that it is supposed to equal the gravity coefficient, which is defined as exactly 9.80665. But when i search google i saw one result saying 9.80665002864, and at first i thought it may have just been a precision error, but when i ran a google search for the number 9.80665002864 then i get plenty of results, all having to do with Newton conversion but none at all had anything to do with gravity. Is it just 9.80665 and all these websites made the same precision error? Or is a kg/newton not the same as exact gravity?
Comment: Newton is a unit of force, not mass, so the title is confusing.  Moreover, the value of $g$, the gravitational acceleration near the surface of the Earth, is not uniform on the surface of the Earth.  There are local variations due to height and geological features below the surface where $g$ is measured.
Comment: Please share a reference for your "exact" value for a "gravity coefficient." I don't know what "exact gravity" means.
Comment: Welcome to Physics SE! Please do have a [tour] of this site. As it stands, your question is rather unclear, since newtons are a unit of force, and kgs are a unit of mass. Edit your post, and hopefully it will have better reception. Good luck, and hope you get what you're looking for!
Answer: There are a couple of misunderstandings in your questions, but I think I can see what is ultimately being asked.  If you don't mind, I need to tidy up your question just a bit:

How many Newtons are in a kilogram, exactly.  I thought that it was 9.80665 by definition.  However, I found numerous sources on the web that seem to give the exact same answer for g, the acceleration due to gravity.  Most all of them seem to give 9.80665002864 meters/sec^2.  What gives?

First off, the others posting answers to this question are ultimately correct - there really is no direct conversion between kilograms and Newtons.  Kilograms is a unit of mass (how much matter is in an object) while Newtons is a measure of the force that the Earth's gravity exerts on the object.  These two may seem like they are exactly the same thing, but they are just different enough to be completely different things.
Now, if we limit our question to "how many Newtons would a 1kg object weigh at the Earth's surface", then yes I suppose there is a conversion between the two, and yes that conversion is about 9.81 m/s^2.
Now, on to the part you asked about the number of decimal places, accuracy, and g being "defined" as 9.80665.  The fact is that g has never had any defined value to speak of (unlike the speed of light, but that's another story).  Most of the best measurements at the Earth's surface put the g number at about 9.81, but this may vary around a bit because the Earth isn't exactly a sphere, and so fourth.
All of these web pages that seem to be giving you the same value of 9.80665002864 must be getting their information from the same source.  Besides, I'm not sure what leads anyone to think that g can be calculated to this many decimal places - moving around from continent to continent will result in different g values that differ by roughly 1%.
Hope this helps.
Comment: For perspective on how unrealistically precise that number is, using Newton's law of Universal Gravitation, we can determine that a 1kg mass a full meter away from your test apparatus would be enough to substantially alter that last digit.  The pull of gravitation of the building around you would certainly have a noticeable effect at that precision.  Not only would it differ if you went to another continent, it'd differ if you went to another room (or even a different corner of the room!)
Answer: g0 = 9.80665 m/s2 was the standard gravity value, adopted in 1901. It is the exact value by definition, it does not have more decimals. It is the theoretical value for g at sea level and 45° of latitude. Precision barometers used at sea were calibrated for this value of g. An elaborate correction formula could be applied for other latitudes and heights. g0 was also used in the definition of the kilogramforce, an obsolete unit of force.
Answer: Standart kilogram is a unit of mass, the Newton is a unit of force. Those are fundamentally different units as other people have noted. You can talk about a force acting on one kilogram $F=mg$ that will change depending on where you are.
However there's a non-SI unit of force called kilogram-force (kgf). It's defined as gravitational force acting on one kilogram in a standard gravity field i.e. $g=9.80665 m/s^2$. It may not be equal to the actual gravitational force acting on a kilogram in this specific place.
Answer: A Newton is a unit of force.  A kilogram is a unit of mass.  There is no conversion between these two units.
Regarding gravity, at the surface of the earth, there is a downward force of 9.81 Newtons (I deliberately reported only 3 significant digits) on a 1 kg mass.  This means that the acceleration due to gravity is 9.81 N/kg, which, if you do proper dimensional analysis, is also 9.81 $m/s^2$.
As you continue learning physics, it is VITALLY important to learn what units are associated with each type of measurement, and it is VITALLY important to learn what dimensional consistency is.  Physics is NOT math, and attempts to ignore units and just multiply a bunch of numbers together are guaranteed to lead to a LOT of confusion.
Comment: The downward force (commonly called "weight") varies sufficiently with location on Earth that three significant figures are too many...
Comment: Yes, Floris ... I'm aware of that.

How many Newtons are in a kg exactly?


Android SQL Delete row not working

Question: Firstly I am creating a Database in a helper class as follows:
public void onCreate(SQLiteDatabase db) {
    String sql = "create table " + TABLE + "( " + ID
            + " integer primary key autoincrement, " + FIELD1 + " text, "
            + FIELD2 + " text);";
    Log.d("EventsData", "onCreate: " + sql);
    db.execSQL(sql);
}// Where public static final String ID = "_id"; ect.

I have then inserted data and I have seen it works by displaying the inserted data in a TextView.  My problems come when I need to delete a row.
I can deleted everything by using
db.delete(TABLE, null , null); (again I can see that this works)
However if I change it to deleted a single row such as
db.delete(TABLE, "_id" + Index, null); Where for example int Index =4;
nothing happens, I get no errors and no delete.
Can anyone help with why this happens?
Answer: SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_CONTACT, _ID + "=" + _id, null);
db.close();

Answer: Try
db.delete(TABLE, "_id = ?", new String[] { "" + Index });

Answer: db.delete(TABLE, "_id=" + Index, null);

Android SQL Delete row not working


What advantages does Linux give me when developing in PHP for the web?

Question:
I'm about to begin a big PHP project with a friend. It's my first time using PHP and I've been wondering wether I should try developing on Linux since it's so popular.
I've had some past experience with Linux and the choice of an editor won't be hard since I know vim (though I've looked at VS.PHP and it's putting me back from the change).
Does using Linux when developing PHP (or any web language) give me an advantage?
Comment: One advantage: freedom
Comment: Yes. You might want to rephrase your question so it isn't a simple binary choice.
Answer: It depends what you call web development and how you do want to work.
For instance running Photoshop natively is impossible (sure with some VM or "emulation" there are ways to do that or you can simply use GIMP.)
If you're planning to do pure coding - it depends on what you love during development.

You won't get as good live editor as dreamweaver although Eclipse and NetBeans do the job of IDE. Sure Eclipse would be obvious choice here.
If you like wamp server on windows, xamp is available on Linux, but it's not as simple. I usually end up with just apache2 and needed modules.

On the other hand:

Make/bash.sh/fab files feels in home under Linux and it may increase your performance a lot doing repetitive commands. Sure there is .bat files but under Linux its way more easier and way more clearer how script should work what commands it should use and ect.
Because it's Linux you will learn how to deploy in such servers much faster.
If you learn VIM (that takes some time) - its fastest editor around. Emacs also fast, but nowhere near VIM speed of editing. Sure don't jump on it too soon - it will scare you!

So thats 3 points for both sides. All in all - Linux is just an OS. Tools makes it good and the person it uses makes it fast/slow. I had problems when i needed older versions of php, but overall I use Linux every day not because its better for development, but because it's way better OS, although it has a steep learning curve. I must say that i don't have huge experience developing in php under Linux so i might be missing some points.
Talking about other web languages:
I don't really know about Ruby, but i heard that its better than on windows due to some(?) services and system tools that downloads gems easily.
Django is way better in Linux - It runs better, it takes half as much to deploy as in Windows (just for developing). Its easy to deploy in Linux servers and pain in the ass to do the same in windows production servers.
Finally I just can recommend to try it, not because it may bring some speed to your development, but because it is Linux and it is awesome.
Comment: On any modern PC Emacs can process input far faster than you can type.
Comment: @kevincline I'm not talking about the processing speed, but about edit speed that you have if you know Vim. Emacs is good as well, but when it comes to editing it's nowhere close the speed of Vim.

This is simply an error in my expression here. I'll edit it soon.
Comment: I will accept that you are nowhere near as fast with Emacs. Many Emacs experts have rejected VIM as being far too slow and difficult to customize.
Answer: One advantage it might give you is that it is more likely to match the deployment environment, although with Windows improved support of PHP that's not necessarily the case.  I've found it more of an advantage to use Linux when developing in Ruby on Rails more than with PHP as you can run into a lot of little annoyances like database drivers.  But Microsoft has done a lot of work to better support PHP, including the Web Platform Installer and the new Webmatrix IDE.
Answer: I believe there's a lot of benefits to doing this on Linux.
First, you will be dealing with a far simpler operating system environment, one that's reasonably well documented, and one for which source is available.  You can have confidence that when you find a bug, you can figure it out.  You won't do that weird, pull-out-your-hair having to decide if Windows is at fault, or your code is at fault, and if the former, how to work around it.
Second, Linux performs better than Windows on the same hardware.  Despite all the flack in the trade press, this is indisputable.  You can easily get away with older or slower or less up-to-date hardware.
Third, Linux and the X11 windowing system are far more customizable than Windows.  Try to do focus-follows-mouse or worse yet, lazy focus follows mouse on Windows.  You can set up your windowing experience as you like it, not as Microsoft Deems Best for you.
Fourth, Linux filesystems make a lot more sense than NTFS.  "Case preserving" filenames? Saints Preserve Us! Alternate Data Streams?  What's wrong with directories?  Why make every file into a directory?  Magic file names like "CONS", "AUX", "LP"?  I hope the inventor of those things got punished.  Linux filesystems have a single root, and individual disks aren't even easily visible, so you don't have piles of special cases to deal with "C:" vs "C:\something".
Fifth, trying things out is monetarily cheaper.  Indisputable.
Answer: Best choice for your dev environment would be the one you can be most productive with. It all comes down to personal preference. That being said, lot of web sites and apps (especially ones written in php) are deployed on linux servers. If you're planning to work on other than .NET-technologies in the future, not knowing your way around is likely to bite you in the ass somewhere along the road. So, at least in some point you should familiarize yourself with basic linux usage. Whether you should do it with this project or sometime later is hard to say. Your productivity might suffer while you learn, but after you get to know the way things work in linux environment, it could yield improvements to your productivity.
Answer: Short answer:
Yes, but you will need to spend more time setting things up to get the benefit and there is a much steeper learning curve.


Genesis 3:1 - "serpent" or "shining one"?

Question: In Genesis 3 the Hebrew word 'nachash' meaning the shining one has been rendered 'snake' or 'serpent'. What possible ground is there for such renditions?
Comment: What is your grounds for interpreting nachash as "shining one"? Actually I'm not aware of any traditions that interpret this Hebrew term other than snake/serpent!
Answer: The notion that נָחָשׁ (nachash) is related to the idea of "shining" is not unheard of.
In The Companion Bible, E. W. Bullinger wrote the following,1

However, the Jewish scholars who produced the LXX certainly understood נָחָשׁ as being a serpent, as they translated it into Greek as ὄφις. This is further confirmed by the New Testament that translated it likewise.

2 Corinthians 11:3

3 But I fear, lest somehow, as the serpent deceived Eve by his craftiness, so your minds may be corrupted from the simplicity that is in Christ.New King James Version. Nashville: Thomas Nelson, 1982.

Γʹ φοβοῦμαι δὲ μή πως, ὡς ὁ ὄφις ἐξηπάτησεν Εὕαν ἐν τῇ πανουργίᾳ αὐτοῦ, φθαρῇ τὰ νοήματα ὑμῶν ἀπὸ τῆς ἁπλότητος [καὶ τῆς ἁγνότητος] τῆς εἰς τὸν Χριστόν.Novum Testamentum Graece. Ed. Aland, Barbara, et al. 28th ed. Stuttgart: Deutsche Bibelgesellschaft, 2012.

Footnotes

        1 Appendix 19 (p. 24 of the Appendix)
References

Bullinger, Ethelbert William. The Companion Bible. Grand Rapids: Kregel, 1999.
Comment: It's an interesting idea, but I can't find this definition in any lexicon. It seems to be his guess of the etymological meaning behind the words נחש, snake, and נחשת, copper.
Answer: Translators render nachash (from the root n-ch-sh) as "serpent" because it's the most plain and simple understanding. There's no indication in the text that it should translated as anything else, but you're correct to associate shining with nachash, although this understanding could be more refined.
Hebrew root n-ch-sh forms and definitions (from The Unseen Realm):

nachash (noun) "snake; serpent" (Genesis 3:1).
nochesh (verb) "to use divination, give omens" (e.g. Genesis 3:4-5).
nachash (adjective) "bronze, brazen" (1 Chronicles 4:12, referring to Ir-Nachash "the city of copper/bronze (smiths)" > nechosheth "bronze; copper", can be applied to divinities/angels [Daniel 10:6]).

It's possible the informed reader should think of all three meanings when reading Genesis in Hebrew, not only one at the expense of others.
Sources: The Unseen Realm (Heiser, 87)
Answer: The Hebrew word נָחָשׁ, nachash, indeed means snake or serpent. You can find it here for example: https://archive.org/details/BDBHebrewLexicon/page/n1275/mode/2up. It is the last entry on the bottom right at 6058 and with Strong's number 5175.
Perhaps you are thinking of Isaiah 14:12 where the English "shining one" or the Latin "lucifer" translate the Hebrew word הֵילֵל, helel. (You can find the word here: https://archive.org/details/BDBHebrewLexicon/page/n499/mode/2up. It is the second entry on the top right page at 2407 and with Strong's number 1966.)
Some interpreters of the Bible have linked this verse with Ezekiel 28:13 where the prophet describes someone as covered with precious stones in Eden and have argued that this figure is the snake in the Garden of Eden in Genesis 3. Thus they conclude that the identity of the shining one (the helel) in Isaiah 14:12 is the snake (the nachash) in Genesis 3.
There are problems with this interpretation. The main issue is that the context in each of these prophetic passages tells us precisely about whom the prophet is speaking and it is not the snake in either. Isa 14:4 specifically states that the proverb (mashal) is against the king of Babylon, and likewise in Ezek 28:12 the lamentation (qinah) is against the king of Tyre.
For more information on the interpretation of these passages check out these short online articles by Craig Keener: http://www.craigkeener.com/does-isaiah-1412-14-refer-to-lucifers-fall-from-heaven/; and http://www.craigkeener.com/does-ezekiel-2812-14-refer-to-the-devil/.
Nevertheless, nachash does not mean "shining one". It means "snake/serpent". "Shining one" is the meaning of helel.
Comment: I would say while Isaiah and Ezekiel both speak of the kings of Bablylon and Tyre the text obviously segues into someone who not a mere human king. The details could not match a human king, but must speak of a power behind those human kings.
Answer: The fact that we already know that the nachash of Eden in Genesis 3 is Lucifer, the shining angel expelled from God's presence, who seduced Eve into rebelling, gives credence to Dr. Heiser's argument that it was not from the animal kingdom, but a highly intelligent spirit being whose objective it was to destroy humanity. Lucifer's beauty and brilliance is documented in the Scriptures, and by reason it must be considered that Eve would have  been far more attracted to a stunningly beautiful angelic being that Lucifer is described to be by the prophets, as opposed to a snake. The argument that the translation of nachash as snake is carried over into the New Testament can simply mean that no writer chose to clarify what the nachash of Gen 3 actually was. The the root word for nachash, also used for the luminous metals of copper and brass, certainly could be used to describe the luminous one, Lucifer. I think that Dr Heiser got it right.
Comment: Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer).
Comment: Hi Jan, welcome to the site. This looks like the start of a great answer--could you add some citations and/or the Biblical passages that support this view. Thanks for contributing!
Answer: The bronze/copper link from the "unseen realm" you posted seems really really really far removed from truth, in point 3 in your post.
in dan10:6 it says just the angel's arms/legs had the appearance/color like polish brass/copper.
https://www.blueletterbible.org/kjv/dan/10/6/t_conc_860006
the word here for copper is NOT nachash but instead nekhosheth in dan10:6.
https://www.blueletterbible.org/lexicon/h5178/kjv/wlc/0-1/
which means like less noble less pure metal "copper, hence, something made of that metal, i.e. coin, a fetter; figuratively, base (as compared with gold or silver):—brasen, brass, chain, copper, fetter (of brass), filthiness, steel."
nekhosheth (h5178) is from a root word of nekh-oo-shaw (H5154) (copper/bronze/steel/alloy)
nekh-oo-shaw (H5154) is from a root word naw-khoosh (h5153) (red, metal, ball ringing, hard, brass, etc)
naw-khoosh (h5153) is seemingly from or related to naw-khash (h5172) (practice of enchanting / divination -  whisper and hissing they do during those evil practices)
then serpent in gen3:1 is naw-khawsh (h5175) (serpent)
https://www.blueletterbible.org/kjv/gen/3/1/t_conc_3001
serpent naw-khawsh (h5175) is from the root word naw-khash (h5172) (practice of enchanting / divination -  whisper and hissing they do during those evil practices)
So if you follow dan10:6 the color/appearance of the angels arms 3 root words chaining down you get hiss
and if you follow the serpent 1 root word you also get hiss.
to me trying to say the serpent was a shining being from that is way way to far of stretch.
plus you have the whole of the rest of the bible and the new testament (greek) to clearly say it is a serpent.  No doubt the devil used the body of the serpent to tempt. We don't know how a serpent looked before it was changed.  It was the most subtle creature of the field, but I don't see anyway to say it was shining.  But maybe hissing/whispering/enchanting makes more sense.
Comment: Welcome to Biblical Hermeneutics and thank you for your helpful answer.  If you have not already done so, please take our Tour: https://hermeneutics.stackexchange.com/tour


Biggest windbg pet peeve

Question: What is your biggest pet peeve related to the windbg debugger from microsoft?
(note: I actually really like windbg if I ignore the unpolished UI.)
Answer: Attempting to dock a window is almost always the wrong kind of dock the first time until :I move the mouse just right. Why can't it have the docking cues that VS2008 has?
Comment: windbgx (the windows store version) might have improved on this. I don't remember being frustrated by docking behavior after switching to windbgx.
Answer: The ridiculous behavior when you attempt to use click-drag to select text on a line that is wider than its physical window.
The pieces of the history window that I need to copy/paste into bug reports are frequently wider than the physical window.  I've gotten so used to the triple-click workaround that I find myself attempting to misuse triple click in other (well behaved) applications.
Answer: Key presses are ignored while the focus is in a source window.  It's not like you can edit the source code from inside windbg.  At least there's the Alt-1 workaround.
Answer: How insanely slow .kdfiles copies new binaries across the 1394 connection.  It can take up to one minute for a large dll.
Answer: Not being able to switch from output window to command window using a key press, I read that 'Alt+1' should work but it doesn't always so I always have to resort to using the mouse. Also sometimes it doesn't remember when I tell it not to ask me everytime if I want to save the workspace when I quit.
Comment: You can press Tab to switch focus between the command prompt and its associated output window. Tab again to go back. If the cursor is already in the output window, typing any character will first switch to the command prompt and then insert the character.

Biggest windbg pet peeve


Uniqueness of Weak Limit

Question: As we know that weak limit of a sequence of Borel probability measures on metric space is unique. Do we have this property for general sequence of signed Borel measures on metric space? Thank you.
Comment: By weak limit, I guess $\int_Xfd\mu_n\to \int_Xfd\mu$ for all $f$ continuous and bounded. Are the measure supposed to be finite?
Comment: Yes, the measures are finite.
Answer: We assume that $\{\mu_n\}$ converges weakly to $\nu_1$ and $\nu_2$. Taking $f=1$, we can see that $\nu_1(X)=\nu_2(X)$ and putting $\nu=\nu_1-\nu_2$, we have
$$\nu(X)=0\mbox{ and }\quad \forall f\in C_b(X), \int_Xf(x)d\nu(x)=0.$$
Take $O$ an open subset of $X$. We can approach pointwise the characteristic function of $O$ by a sequence of continuous bounded functions, which gives, by dominated convergence and decomposition of $\nu$ that $\nu(O)=0$ for each open subset $O$. Since the open subsets forms a collections stable under finite intersections which generates Borel $\sigma$-algebra on $X$, we deduce that $\nu=0$, hence $\mu_1=\mu_2$ and the limit is unique.

Uniqueness of Weak Limit