Wikipedia:Reference desk/Computing

From Wikipedia, the free encyclopedia
Jump to: navigation, search


The Wikipedia Reference Desk covering the topic of computing.

Welcome to the computing reference desk.
Want a faster answer?

Main page: Help searching Wikipedia

How can I get my question answered?

  • Provide a short header that gives the general topic of the question.
  • Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
  • Post your question to only one desk.
  • Don't post personal contact information – it will be removed. All answers will be provided here.
  • Note:
    • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
    • We don't answer requests for opinions, predictions or debate.
    • We don't do your homework for you, though we’ll help you past the stuck point.



How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

  • The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
 
Choose a topic:
Computing desk
 
See also:
Help desk
Village pump
Help manual


February 16[edit]

Forcing Google to search for all terms (without quotes)[edit]

I'm not sure if this is new or if I've just never noticed it before, but I tried a Google search where I want results containing all of the terms (even if that's zero results) and a search in quotes is not useful for the search I was trying. When I did that search it gave me many, many results but at the bottom of most was the legend "Missing: Term1 Term2". I then tried the search again but this time placed a plus sign next to each term; I got the same results. How do I force Google to search each term? Thank you 173.68.77.60 (talk) 15:30, 16 February 2017 (UTC)

By "term" do you mean word or phrase? If the former, then you can put a plus sign before each word, such as +Term1 +Term2. If the latter, I'm afraid you're going to have to use quotes. Also, try the "advanced search" function, which will let you fill out a form and structure your search appropriately. ᛗᛁᛟᛚᚾᛁᚱPants Tell me all about it. 15:36, 16 February 2017 (UTC)
Hi :MjolnirPants. I don't understand your answer since I explained that I already tried placing a plus sign in front of each word and it made no difference. If there's no way to do it, then that's the answer, but I was hoping for some clarity. To recapitulate, say I wanted to search only for pages that contained all of the terms grapefruit goat grandiloquent and green but not in any order – and without having Google find pages that contain some but not all – is there a way? As I said I tried +term1 +term2 +term3 +term4 but it made no difference. It still returned results for pages not containing them all. 173.68.77.60 (talk) 22:16, 16 February 2017 (UTC)
You're trying to use google like a library reference search, which isn't what google is designed to be. Google is designed to parse the sort of language typical users use to try to describe the results they want, and present results which are relevant to that. Bing and Yahoo do the same thing. In the earlier days of the web, the difference between web search engines and the existing technology known as search engines was the subject of a lot of tech articles and opinion pieces. The way they work is really quite different. So one thing I would suggest is simply telling google what you want, such as Grandiloquent green goats eating grapefruit or try to think up similar descriptions that would contain all of the phrases you want.
One thing I will tell you: If google said it found no results containing all of those words, then it found no results containing all of those words. Finding an obscure way of phrasing search terms to produce the exact function you want will not change that, mostly because adding the plus signs produces almost exactly the behavior you want. When it found no results, it chose instead to show you results similar to the results it calculated it might have shown you had it found any. ᛗᛁᛟᛚᚾᛁᚱPants Tell me all about it. 22:27, 16 February 2017 (UTC)

Google search abandoned the plus a very long time ago [1]. Often suggested to be relating to Google Plus but I don't think this was ever confirmed [2] [3] and AFAIK whether due to the failings of Google Plus or whatever, you still have to use quotation marks before the plus if you want to actually search for it and they don't use it for anything else either.

Anyway whatever the reason, you've had to use quotation marks since. I don't know if you understand how to use quotation marks properly. They do not have to be used for phrases and you aren't restricted to one. If you just want to search for all the terms exactly, you use "grapefruit" "goat" "grandiloquent" "green". This is all described in Google's own help for search operators which isn't a particularly long read [4]. IIRC, the plus operator didn't really work any different, for example "goat" will not generally return goats or "green" greens etc (or if it does, they will be very low priority), but the + worked the same. If I'm remembering wrong and +goat did return goats etc with resonable priority then there is AFAIK no way to completely replicate this behaviour other than using your own complicated searches like "goat" OR "goats".

Incidentally this page is perhaps not surprisingly the first search result for me for that search. (It's quite high up even without the quotation marks.) The next ones are almost all dictionaries e.g. [5] is second although I do get [6] [7] [8] [9] [10] [11] [12].

If for some reason you don't want to use quotation marks, I guess you'll have to develop a Greasemonkey or plugin for your browser that will automatically convert plus into quotation marks and then also modify the page so it looks like you used plus.

Nil Einne (talk) 23:45, 16 February 2017 (UTC)

Well then. Go screw yourself very hard with something very rough, google. You suck. I've been using the + operator as recently as last week, with apparent success. Now I can't trust google, I'm just going to have to resurrect Altavista. But the ability to do it is still there, just enclose each word in quotes. ᛗᛁᛟᛚᚾᛁᚱPants Tell me all about it. 23:58, 16 February 2017 (UTC)
Did you not notice, as the OP did, that it doesn't work as expected? Also IIRC and I think I noticed this in one of the stories about abandoning the plus, they did warn you when you tried using it in the early days of them abandoning it. Nil Einne (talk) 00:27, 17 February 2017 (UTC)
No, the results were exactly as I expected, at least on the first page. It returned results with all of the words at the top of the results, then returned results missing one word or another, noting which word was missing in the result. ᛗᛁᛟᛚᚾᛁᚱPants Tell me all about it. 13:26, 17 February 2017 (UTC)
For the record, I rarely searched that way, which explains why I never noticed that it didn't work right every time. I usually use google the way it was intended, by describing my desired results in common terms, because that's what google is good at. ᛗᛁᛟᛚᚾᛁᚱPants Tell me all about it. 16:07, 17 February 2017 (UTC)
Actually I was mistaken. After some more testing I've found in some cases at least, Google does search for terms with + in front of them when you add it, although as with general searching and the reason for this question, they will not only search for terms with + in front. So yes, I guess their desire to allow + to be a normal part of the search term was most likely the reason it was abandoned. For example, try grapefruit goat +grandiloquent green will return some results which use '+grandiloquent' (mostly they are dictionaries and also have +green etc rather then Google Plus stuff), but not exclusively. Anyway I also wanted to clarify that you don't have to use quotation marks for every words, you're free to only use it for some as with the plus. For example grapefruit goat "grandiloquent" green. Nil Einne (talk) 00:27, 17 February 2017 (UTC)
I thought the plus sign had been deprecated due to its use on Google+ (though admittedly, that article says nothing of the sort). Matt Deres (talk) 12:30, 17 February 2017 (UTC)

February 17[edit]

Email attachments[edit]

When you send an attachment in an email that's tiny otherwise, why is the email so much bigger than the attachment? The page on Email attachment says "The common Base64 encoding adds about 37% to the original file size." Why does it do that? 208.95.51.115 (talk) 15:46, 17 February 2017 (UTC)

Base64 is an encoding scheme that uses padding to ensure that the data is separable into discrete chunks, making it easier to process and more difficult to decode (when encrypting for security reasons). The use of Base64 in email is not for security in that sense, but rather to prevent data loss during transit. The way emails are handled, data within them can be dropped if it does not represent a printable character, because email was designed to be text-only. The Base64 protocol basically converts a string of data (ASCII or Unicode text, .jpeg images, .mp3 sound files, etc.) into a string of ASCII characters to prevent email servers from dropping unrecognized portions of the data. ᛗᛁᛟᛚᚾᛁᚱPants Tell me all about it. 16:04, 17 February 2017 (UTC)

Question about Futurists[edit]

Hello,

I am just wondering who are some of the more well-known futurists (current and past)?

Thank you. — Preceding unsigned comment added by 2600:8803:2001:1E00:384B:D62F:897B:7626 (talk) 21:18, 17 February 2017 (UTC)

We have a List of futurologists article. -- Finlay McWalter··–·Talk 21:40, 17 February 2017 (UTC)
The nouns Futurist and Futurologist have one Wikipedia article but are only partly synonymous.
futurist n.
  1. An adherent to the principles of the artistic movement of futurism.
  2. One who studies and predicts possible futures.
futurologist n.
  1. A person who practices futurology, i.e the scientific forecasting of future trends in science, technology or society
For example, several members of the "Bloomsbury" literary group who shared ideas opposed to prevailing Victorian conventions (ideas such as women's suffrage and post-impressionist art) will be termed futurists, not futurologists. Blooteuth (talk) 00:18, 18 February 2017 (UTC)


February 18[edit]

Website without domain name[edit]

(1) If I want to have my own website, can I reserve a numerical address (IPv4 or IPv6) without cost, and thereby avoid the cost of registering a domain name? (2) If I am obligated to accept an IPv6 address because no IPv4 addresses are available, can I promote the website by submitting the website name to search engines?
Wavelength (talk) 00:21, 18 February 2017 (UTC)

It depends a lot on how your web content is hosted. Do you already have a host set up? clpo13(talk) 01:07, 18 February 2017 (UTC)
No, I do not. What do you recommend in web hosting?
Wavelength (talk) 01:11, 18 February 2017 (UTC)
(1) No one will use your site without a domain name. Also if/when your IP address changes everything with the old address on it is now wrong. It is technically possible to connect with just an IP address, but a) there is no guarantee every piece of software will allow this, and it might be outright prevented by some institutional (corporate, school, etc.) networks; b) average people will wonder what the heck that string of alphanumeric gibberish is. Domain name registrations are not very expensive. (2) You don't "submit" your website to search engines. That's an idea from the good old days of '90s "Web portals" like (the original) Yahoo and Lycos, where actual humans compiled listings of sites. Today's search engines work by automatically crawling the Web, following hyperlinks. To get your site to show up in search engines, you have to get other people to link to it. --47.138.163.230 (talk) 03:32, 18 February 2017 (UTC)

Pair.com ( https://www.pair.com/webhosting/shared.html ) is good. $5.95 per month basic hosting. Using an IP address is a Bad Idea, because dedicated IP addresses cost more than domain names. Shared hosting (many domain names on one shared IP address) is the way to go. Namecheap ( https://www.namecheap.com/ ) is a good place to buy a domain name. --Guy Macon (talk) 03:41, 18 February 2017 (UTC)

Ah the good old days! When one did one's own routing typing in the various ip numbers to get there. What is the point of a domain nobody ever looks at? Because that's what you'd have. And it would be more expensive too. Dmcq (talk) 09:57, 18 February 2017 (UTC)

Without a domain name, you're going to have trouble finding cheap hosting. They want to put a bunch of virtual servers on a smaller number of physical servers. That presents difficulties without a domain name. (Although some might allow you to use a subdomain off of the hosting company's domain. That used to be common back when domains were expensive. Haven't seen it in a while, though.)
If you're setting up your own physical server in your basement, it might be feasable to save $9.95/year by skipping a domain, but only if your ISP offers static IP addresses, which they probably don't.
Nowadays there's not much point to trying to avoid buying a domain name. They cost only ten bucks a year for a dot-com and some of the weird ones cost even less. dot-party domains seem to be available for a buck a year. What a deal! ApLundell (talk) 14:49, 20 February 2017 (UTC)

Reporting spam/phishing[edit]

I've recently received some emails that looked like spam or phishing, and since they were sent from addresses affiliated with major universities, I notified both institutions' IT security offices about these incidents. However, in both cases, my reports got rejected immediately by the recipient addresses (apparently they thought I was spamming or phishing them), so I had to report these cases in a more roundabout manner. The same thing has happened at other times in the past — I can't report something somewhere because the report is misinterpreted by the receiving email server, or even I can't send the report because my email server thinks that my computer's been taken over by a botnet and sending out spam itself.

Since computer science is constantly studying ways to make computers act like humans (e.g. passing the Turing test) and ways to ensure better information security, and since tons of institutions maintain abuse lines where people can report fake emails, I'm guessing that scholars have studied the fact that accurate reports of disruptive emails can get misidentified as disruptive themselves. Could someone point me to research on the subject? Nyttend (talk) 06:20, 18 February 2017 (UTC)

Sorry, this isn't what you're asking about, but you do realize that the institutions aren't actually involved, right? While the emails might have looked like they came from Harvard and Yale or whatever, they actually came from some anonymous creep. What you did was right-intentioned, but there's not a lot they can do about it. Mark as spam, delete, and move on. Matt Deres (talk) 13:11, 18 February 2017 (UTC)
As Matt writes above, it's probably best not to pass on any e-mails with suspicious-looking attachments because they probably came from a dangerous source and had a spoofed sender address. The universities probably have better spam filters than you have. The exception is suspicious messages purporting to come from banks. These organisations often ask for fake messages to be forwarded to their phishing department so that they can take appropriate action to take down any fake websites. I don't know of any research reports. Perhaps someone else can link to some? Dbfirs 13:35, 18 February 2017 (UTC)
With both emails, the sender's "name" was that of a different university, but in both cases, the actual addresses were university-affiliated, and when I decided to get around the spam filter by +poning people with the IT help desk, they actively encouraged me to forward these emails. Nyttend (talk) 15:18, 18 February 2017 (UTC)
What do you mean by "the actual addresses"? It's pretty trivial to spoof most of the headers in an email, so the From, Reply-To and similar headers can't be trusted. The only things that can really be trusted are those that are cryptographically secured, like DKIM-Signature. CodeTalker (talk) 18:09, 18 February 2017 (UTC)
You can trust the last entry in the path -- that's your email system. And you can trust the next one up -- that's where your email system got the email from. If that system is one that you trust, then you can trust where it says it got the email from, and so forth. --Guy Macon (talk) 18:53, 18 February 2017 (UTC)
You're referring to the Received headers, and what you say is true, as far as it goes. But Received headers can be forged too, and many legitimate emails pass through systems which you may not have any knowledge of, so can't tell whether you should trust them or not. CodeTalker (talk) 19:57, 18 February 2017 (UTC)

But the fact they can be forged is largely irrelevant since what can't be stopped is your own email system's practice. If you know your own email system's practice you should know which received header was placed by it. It's fairly unlikely your own email system's header was forged anyway, it's just too complicated for most spammers so you don't even need to know where exactly your email system will place the header, just which one it is. But in any case, you just need to pay attention, if you're not sure where your email system will place the received header, just make sure there is only one. If there seems to be 2 each claiming the email was receive from 2 different places then you know there's a problem.

While you're right you can't always be sure of whether you can trust the system the email passed through, often you can be resonably sure for emails from large businesses since they use well established systems and nowadays emails tend to pass through very few external hops. The key point here that I often make (and I think may be at least partially Guy Macon may be making) is that while people often claim you can't tell from the headers whether the email actually came from your bank (or whatever), by the headers without DKIM etc, because everything can be forged, this often isn't true.

If you know what you're doing (and to be fair, this is something beyond the average user) you can generally get a good idea. If your email system says it received the email from your banks email systems (from my experience this is fairly common with important emails send by the bank), then it's fairly likely the email was sent by someone in the bank, or your bank has major security flaws and are allowing unconnected parties to use their system to send emails.

Of course you probably shouldn't always trust everything sent by your bank. And I also question the security practices of a bank who don't use SPF etc nowadays anyway. But the point is these concerns arise for other reasons not because you can't work out from the headers whether it's likely your bank sent the email. Now if your email system says they received it from spammer.spam or some random small business, then it's fair to think it probably wasn't sent by your bank.

If spammer.spam or the small business claims they received it from your bank then yes that's probably forged. Although with modern email practices you don't even really need to know your banks norms to guess there's something dodgy the moment you see your email system received it from spammer.spam or some random small business.

I'm not denying there can sometimes be uncertainity. For example, one bank I referred to which sends important emails directly from their email system also uses Campaign Monitor for at least some of their advertising campaigns. Is Campaign Monitor trustworthy enough that if they say it was coming from my bank this is true? Probably but depending on your security requirements this may not be enough.

Nil Einne (talk) 04:07, 19 February 2017 (UTC)

While I agree with others from your description most likely the uni wasn't actually involved in the emails, there seems to be some contradiction here. It's not clear from your original comment whether this was a phising attempt, but there's no reason why only a bank is going to want to shut down websites used for phising. Any large organisation and most small ones are likely to want to avoid their customers (or whatever) authentication info being stolen. The question is more whether the organisation can do anything than the particular organisation. Banks do probably have larger and more dedicated teams, but that's ultimate the key difference. If someone is sending malware, whether it's claiming to be from a bank, a university or FedEx, most likely none can do much except warn their customers if necessary. This may be more likely with the bank although some other organisations may be just as likely to warn. If someone is sending a 411 scam or adverts for "Viagra", again there may be not much that will be done whether it's purported to come from a bank, a university or FedEx. As said, if someone is attempting to phish using external websites all organisations are probably going to want to shut those down. It may be more likely that something purported to be a bank is a phising attempt but something claiming to be from a university is something else, but that's a different point. Nil Einne (talk) 04:22, 19 February 2017 (UTC)
If you receive spam or phishing emails, per RFC 2142, you should be able to forward them to an abuse email address. E.g. spam from something@yale.edu can be forwarded to abuse@yale.edu. Ideally, your email won't be rejected, as the mail server should not be screening emails to abuse. That's the whole purpose of that particular email address - it accepts fishy emails to be reported. Spam reporting has some limited info. Avicennasis @ 18:24, 23 Shevat 5777 / 18:24, 19 February 2017 (UTC)

CPU question[edit]

If you took out the CPU chip out from the motherboard and carefully soldered wires from each contact pin to the corresponding pin on the motherboard, would the CPU function? Would it be slower than directly connected? — Preceding unsigned comment added by 189.201.241.54 (talk) 19:28, 18 February 2017 (UTC)

I did something alike in 1980 with an RCA 1802 8-bit CPU and it worked. I believe the clock speed was 1 MHz. Today CPU's are much faster (clock speeds more than 2000 times faster). High speed electronics needs a careful PCB design, not sloppy wires. It seems highly unlikely to me that it would work without drastically reducing clock speed (which could cause it's own problems). Jahoe (talk) 20:50, 18 February 2017 (UTC)
Yes, the signals take about a nanosecond to travel a foot, so if you have several inches of wire the delays would almost certainly cause timing problems for gigahertz clock speeds. Dbfirs 21:04, 18 February 2017 (UTC)
Good point to mention the delays. I thought in terms of impedance mismatch, signal reflections, parasite capacity, etc. In other words, signal spaghetti. ;) Jahoe (talk) 21:40, 18 February 2017 (UTC)
There's also capacitance between the wires to consider. Several inches of wire would create extra capacitance of maybe 20-50 picofarads between them. This capacitance would have a slowing effect on the rise time of the signals the wires carry, meaning that the signals would not rise or fall as rapidly between zero and full voltage states as quickly as they did previously. Unexpected behavior of the CPU would occur in time-critical operations. The extra capacitance also means that a false signal might be induced to appear in an adjacent wire, creating havoc. In general, the computer could be expected to run slow and probably crash. Akld guy (talk) 19:22, 20 February 2017 (UTC)

what were early 8-bit home computers (with a front panel) good for?[edit]

I'm thinking of the Altair and the IMSAI Asmrulz (talk) 21:49, 18 February 2017 (UTC)

The same thing other computers of the era were good for. Since you mentioned the front panel, I suspect you're thinking all people did was plug them in and watch the lights blink. Actually, to do useful things, you connected them to peripherals. The Altair article mentions connecting it to other devices like teletypes, often via RS-232. A lot of companies were started to sell hardware for the new microcomputers. This was no different from the mainframes and minicomputers of the era. For instance, here are Dennis Ritchie and Ken Thompson at work on the Bell Labs PDP-11 sometime in the '70s. --47.138.163.230 (talk) 22:06, 18 February 2017 (UTC)
I'm not thinking that. But you have to admit the I/O capabilities were limited. And how many people had a discarded teletype sitting around, anyway? I've been toying with microcontrollers for the past year or so. Hence I'm curious what people typically used computers that are hardly more than a glorified CPU evaluation board for. Asmrulz (talk) 22:53, 18 February 2017 (UTC)
The two types you mention weren't really home computers (a bit too expensive for that), but machines for small businesses. They were used for financial administration, word processing, inventory, spreadsheets, etc.
Home computing didn't really take off before the 1980s (3 to 5 years later than the types you mention). These home computers were used for games (tetris, kings quest, leisure suit larry, etc.), word processing (WordPerfect) and as a general introduction to the new technology. Many owners stopped using them after a while (stuck with the same question as you ;), others (like me) got enthusiastic and went on a quest for a real purpose of their new and beloved toy. ;)
Sometimes (varying per country) employers financed home computers to have their staff practice at home in their spare time. (Doesn't sound good perhaps, but I loved it.)
In my view, home computers were fun, but didn't have a real purpose until the internet came to the family home in the 1990s. And even today, most PCs at home are little more than internet terminals. They're a bit like telephones, which have little use without a telephone network.
Well, that's how I look back on it from my own experience. Other people may have completely different thoughts on it. But perhaps this is a (partial?!) answer. :) Jahoe (talk) 22:58, 18 February 2017 (UTC)
TeleVideo 925 glass teletype
Oh, and those computers with front panel weren't typically used with teletypes, but with "glass tty's", like the Televideo pictured. Connecting two or four terminals was possible, although one was more common. Jahoe (talk) 23:09, 18 February 2017 (UTC)
The Altair and IMSAI weren't really marketed to businesses; they were marketed to nerds who wanted to mess around with computers (and I say that as a proud nerd). An individual (with sufficient disposable income) could buy their very own computer to tinker with, some assembly required. That was a big deal when up to that time computers took up at least a room, cost as much as a house, and required at least several experts for care and feeding. The first microcomputers that were marketed to businesses and professionals for "serious work" were the Apple II and IBM PC (which, of course, didn't require you to assemble them from parts). See also history of the personal computer. --47.138.163.230 (talk) 00:18, 19 February 2017 (UTC)
Although the Altair and IMSAI were very popular, there were other early computers. I myself started with an NCR Century 100 (My high school bought one and started teaching classes on computers with it), and my first home computer was a COSMAC VIP, which I built from a kit in 1978.
You too can own a COSMAC ELF! See [13] and [14]. --Guy Macon (talk) 01:25, 19 February 2017 (UTC)
I was around at the time. They were so limited that I didn't want one. I either used a mainframe or my programmable calculator, which could store programs to a magnetic strip and read them back. I also had a printer to use with it. I think that a programmable calculator at the time was a lot more useful. Bubba73 You talkin' to me? 01:42, 20 February 2017 (UTC)
DEC GT40 graphics terminal running Moonlander
They where special "adult toys", like model railways. You could do little basic stuff with it but they where very fascinating for everyone who liked Enterprise/Star Trek: The Original Series. Actually there also where some very early, simple games availabel back then, like Lunar Lander. They where very rare tho as maybe 1 out of 10,000 People, even or less, had one, which made it double fascinating ofcourse, so they where priceless, for bragging about having one, for some. --Kharon (talk) 02:14, 20 February 2017 (UTC)
Radio amateurs began using early 8-bit computers for sending Packet radio messages, keyboard to keyboard. The first continent-to-continent packet radio conversation was made quite a few decades ago. However, most operation was, and still is, on the 144 and 432 MHz amateur bands. Radio amateurs also set up Bulletin board systems, interlinked between nodes in major cities via radio a decade before the internet took off. Akld guy (talk) 04:32, 19 February 2017 (UTC)
interesting. where I'm from, non-IP, modem networks such as FIDO were in use well into the late 90's-mid 200x (landline, not radio, though) Asmrulz (talk) 04:59, 19 February 2017 (UTC)

First person to send fax and slowscan TV over the cellular network[edit]

I believe I was the first person to achieve this. How can I place this in Wikipedia in order to determine if this is the case?Bob Moore 100 (talk) 22:29, 18 February 2017 (UTC)

You can't put WP:original research in any Wikipedia article, but if details of your achievement have been published elsewhere in WP:reliable sources then the fact can be recorded here. It is not possible to use Wikipedia to determine whether the claim is true or false, though someone might be able to find references to similar claims. Dbfirs 22:45, 18 February 2017 (UTC)
Also, on Wikipedia it's considered not done to write about yourself or your own achievements (at least not outside your user page). Of course others could do that for you just fine. Jahoe (talk) 23:34, 18 February 2017 (UTC)

February 19[edit]

Lost Contents[edit]

As I was using MS Word, I accidentally deleted the contents than saved the document. I realised this thereafter reviewing the document. How do I re-collect the information? 103.67.159.200 (talk) 04:36, 19 February 2017 (UTC)

Apparently there is a "redo" button. [15] 80.5.88.48 (talk) 09:17, 19 February 2017 (UTC)
Guess "undo" was meant. Only if the Word-session is still open you can try to undo (Ctrl-Z) the deletion and hit save again. Once MS-word is closed, the undo-memory is lost.
If that doesn't work, look in the folder containing the original document for one of those automatic backup files MS-word makes.
Also, you may have a backup of your original file. If not, start to backup your work from now on. Jahoe (talk) 12:07, 19 February 2017 (UTC)
This happens quite regularly where I work (a school) and it is the teachers who usually lose their work. We drum into them, as soon as you've opened a new MS Office document, save it immediately and then carry on working. The autosave means they have a good chance of recovering their work, but only if they have saved it once. --TrogWoolley (talk) 13:09, 19 February 2017 (UTC)

Lists of large safe primes?[edit]

I'm looking for some safe primes of around 300 or so digits. Is there a standard listing of that sort of thing? I did take a stab at generating them using a fairly efficient computing algorithm - which does fine in the tens of digits - but of course a jump in order of magnitude just creates such a much larger search space that I've yet to see a single prime of that size at this point. Any ideas? Earl of Arundel (talk) 08:30, 19 February 2017 (UTC)

It should be pretty easy to generate safe primes using the OpenSSL library. Here's a program which claims to do that, although I haven't verified whether it works as advertised. [16] If you're using primes for cryptographic purposes where the primes need to be kept secret, you will of course want to generate your own primes and not rely on any published list of primes, since an attacker would have access to such published lists. CodeTalker (talk) 17:16, 19 February 2017 (UTC)
Thanks, I'll give that a go. On a side note, one of the two programs I've been running did produce a safe prime overnight:
 222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222801407 
That was generated by sequential search. The randomized algorithm is still trying to find its first! I actually expected the latter one to locate primes fastest (as the article on generating primes for one suggests). Then again, the randomization routine does impart a bit more overhead than a simple increment, not to mention that a measure of luck is involved with purely random samples. Earl of Arundel (talk) 18:52, 19 February 2017 (UTC)
Funny, just minutes after I posted that the randomized algorithm produced this one:
681585627032540283407897049573943438864991564384081864606798355681927368882418588940610880082924107725344352426869730927204896839743453854437265009790110718860756175638300841264131752404495959142547366913702122243460812876710321117513484795819233714299670604738148021754597371318698761395812018572519
At this rate, I just might have a few more primes to work with by the end of the day! We'll see... Earl of Arundel (talk) 19:32, 19 February 2017 (UTC)
Many math programs can easily handle this size. Below is a simple PARI/GP line which took 2 GHz hours. It could be more efficient by trial factoring both p and (p-1)/2 before prp testing. nextprime and ispseudoprime make prp tests almost certain to produce primes. isprime would make primality proofs but be slower. PrimeHunter (talk) 23:00, 19 February 2017 (UTC)
for(n=1,5000,p=nextprime(random(10^300));if(ispseudoprime((p-1)/2),print(p)))
146826802325178743666647061779713417611259934811900522577544206839763515828687825279365134210939056543140136635939259809100232274940676856687607875001704527141790658441630421867014340205717004954887742192841795596397643359593336357804864669571879248567500042385640119936769305112452232482315185400627
189245147177606331584023875953267114326398737777762360150885641279051616456892584088107824699894789233671588064860339727298515859969383896839558666217153218476356205131691803322265876463410618767738035270628788079093798634481718643230178954554082043541820540195807474059566449769729300898569439347219
906746488931122279923087816774254262549325961021203686871024593960273364483640837461275651353839912478276312989231907136777434371442297783809058139703704548112582549231057887119837609961275494698594028464424938139236812786325180573685365716054578878269276609138278646089652565880503149299047623725983
935963679945159621618108135650731602316123462844739918966791054002220621454733515962631838558167071714943415781502503512108093455147689164719674990397035764248808486754562236727013255473894080575022971540677037449750273014794528407667454650131576454015775014701175216242011377646611112897139737772263
900868433651123753195857434154886592863492075718887214387046829406809805283361296277175990663685161530183997243896077623165157756007099732429029873106259069821886766195661979481563101826429797570890866473513531898785774896418926615059720815237664116812063491035355207065882456370964859448027182804663
78051553050775412450764922949272607832888279795219210490159546292573544344409789339902163711499864234225334440363474968206590948838140508077711461378723988713387646192208969558413389127673105435094693170772364285590152222728794669485480277618571809396011062579114664522387048289471601386870869721619
Ah, so I could simply have PARI/GP first generate a list of suitable Sophie-Germain/safe-prime pseudoprimes pairs and then pass those to the more expensive isprime function to prove their primality. Nice. Well thank you very much, PrimeHunter! Earl of Arundel (talk) 18:27, 20 February 2017 (UTC)
Update: PARI/GP does in fact seem perfect for this task: I have both randomized and sequential search routines implemented which are already pushing out proven safe primes. I was also able to verify that the examples you'd provided are indeed safe primes as well, and very quickly at that (less than a minute for all six of them!). So again, many thanks for the suggestion. Earl of Arundel (talk) 20:25, 20 February 2017 (UTC)

Last bullet in list different color[edit]

So I'm trying to figure out the bug in this code:

{|style="background-color:#ffffff; text-align:left" width="100%" cellspacing="10" |- |style="text-align:left;" valign="top" width=170 rowspan="3"|[[{{{1}}}|150px]] |style="text-align:left;" valign="top"|{{{2}}}
Randomtext A:
{{{3}}}

|- |Randomtext B (if applicable):
{{{4}}}

|- |align="center" colspan="2"|

|}

The blue part, when there are multiple bullet entries, all the bullets are blue except the last one, which is black. The text remains blue though. Stumped as to why. RegistryKey(RegEdit) 14:43, 19 February 2017 (UTC)

I suggest you try it in different browsers, to determine if it's just be a bug in the browser you are using. StuRat (talk) 17:59, 19 February 2017 (UTC)
StuRat I checked it on Internet Explorer and Chrome, still same issue. RegistryKey(RegEdit) 01:10, 20 February 2017 (UTC)

How's PHP run?[edit]

When you have something like <?php echo '

Hello World

'; ?> in a file and an Apache2 server running, what runs this bit? There's no PHP process running in the server. Does Apache starts a PHP process, runs the bit, and close it each and every time someone hits the page? --123abcnewnoob (talk) 15:46, 19 February 2017 (UTC)

It starts PHP for each request. PHP is programmed to only look for the bits delimited by <?php and ?> and echo the rest verbatim. In FastCGI mode, however, to avoid process spawning overhead, there's one PHP process sitting in memory that may handle many requests over its lifetime. Alternatively Apache may pass the PHP to mod_php which is its in-process PHP interpreter. Asmrulz (talk) 16:02, 19 February 2017 (UTC)

February 20[edit]

Sender's messages in Courier New[edit]

Some Gmail messages I received from a person are written in Courier New, while some are in default Times New Roman (the sender's email is also Gmail). Since Gmail now doesn't have the Courier New font, why it could be so? Perhaps copy-pasting and scam? Brandmeistertalk 20:36, 20 February 2017 (UTC)