Ubuntu runs with a larger resolution than what my screen allows
My computer boots to a black screen, what options do I have to fix it?
How to validate phone numbers using regex I'm trying to put together a comprehensive regex to validate phone numbers. Ideally it would handle international formats, but it must handle US formats, including the following:   1-234-567-8901 1-234-567-8901 x1234 1-234-567-8901 ext1234 1 (234) 567-8901 1.234.567.8901 1/234/567/8901 12345678901   I'll answer with my current attempt, but I'm hoping somebody has something better and/or more elegant. How to zero out a drive? Homework question on whether two quotient spaces are homeomorphic Squares in arithmetic progression It is easy to find 3 squares (of integers) in arithmetic progression. For example, $1^2,5^2,7^2$.  I've been told Fermat proved that there are no progressions of length 4 in the squares. Do you know of a proof of this result?   (Additionally, are there similar results for cubes, 4th powers, etc? If so, what would be a good reference for this type of material?)    Edit, March 30, 2012: The following  in MO is related and may be useful to people interested in the question I posted here. Passing directly an array initializer to a method parameter doesn't work How to copy files via terminal? I have read about copying files with terminal but these examples will help me a lot. So here is what I want to do:  Examples:   I have a file in /home/levan/kdenlive untitelds.mpg and I want to copy this file to /media/sda3/SkyDrive and do not want to delete any thing in SkyDrive directory. I have a file in /media/sda3/SkyDrive untitelds.mpg and I want to copy this file to /home/levan/kdenlive  and do not want to delete any thing in kdenlive directory  I want to copy a folder from home directory to sda3 and do not want to delete any thing on sda3 directory and opposite I want to cut a folder/file and copy to other place without deleting files in that directory I cut it into. I am working on a BLDC sensorless motor. I need to detect BEMF Zero-cross event. My Motor is working on 24 Volt power.  Now I need to detect the back E.M.F. As refered in .  My MCU is working on 5V. And ADC range is 0 to 5V. I need to convert the BEMF feedback signal to ADC channed in this.  As we know voltage divider rule says:   In Figure I :-- Now signal (U) which I need to feed is applied at the middle of the two resistors R1 &amp; R7. So what is the value of voltage VU ?   In Figure II :-- Sum of U,V,W  is applied at the middle of the two resistors R11 &amp; R15. So what is the value of voltage VN ?  Also, what are the roles of capacitors C1 &amp; C4?  Please can someone explain the MATH behind this ? Why is voltage same for the two resistors connected parallel in circuit? We know that the electric field inside resistor produced by battery is the actual thing that pushes the electrons in it to move and thus producing some current. We also know that strength of electric field can be described by the electric flux which is the total amount of fields passing through an area. That flux when combined(multiplied) with charge of electron gives the amount of force on it. Now comes our two resistors R1 and R2. Assuming a number of field lines coming out of a terminal going towards another terminal through these resistors, the field lines should get divided into the resistances R1 and R2. Therefore giving a reduced flux through each resistor than in a series. Which will then give a lower voltage for both resistors. Wasn't the electric fields strength divided across resistors in parallel? What is the main cause of voltage? How electrons get a force to produce current even when the wire is very long in? I think it is better to understand with reality than analogy. Please don't give misleading pictures When is it appropriate to create an entity instead of a new content type? What is the benefit to creating new entity types over just building a new content type?    It seems a bit overkill to do all of the custom coding that is required to create a new entity when you have all of the CRUD and Views functionality already built into content types. I've noticed that, if I add \n to a pattern for substituting using sed, it does not match. Example:  $ cat &gt; alpha.txt This is a test Please do not be alarmed  $ sed -i'.original' 's/a test\nPlease do not/not a test\nBe/' alpha.txt  $ diff alpha.txt{,.original}  $ # No differences printed out   How can I get this to work? Let $p$ be a prime. Suppose that $\gcd(a, b) = p$. Find $\gcd(a^2,b)$ for all integers $a$ and $b$. Let $p$ be a prime. Suppose that $\gcd(a, b) = p$. Find $\gcd(a^2,b)$  for all integers a and b.   I was able to prove that $\gcd(a^2,b^2) = p$ but I don't know if it helps.  Any help is greatly appreciated. Do new wire runs in an existing ceiling need to be stapled down? I've heard some people say that code requires wiring in the wall to be stapled to framing every so often (how often?), but when you are doing a remodel, is that necessary?  I have a two story house, and would like to remove one standard dome light on the first floor ceiling and replace it with 6 recessed lights.  There is about 12" of empty space between the floors, and it seems easy enough to run the wire from light to light without cutting any drywall except for the 4-5" holes required for the lights. However, there's no way I'd be able to staple the wiring down.  It's just going to be loose in the ceiling, running through a small hole in the I joists every once in a while.  They sell "remodel" light cans that are made specifically so you only have to cut a hole big enough for them to fit in, so this seems like a common job.  What am I missing and how can I do this job in the most correct way?  This is in Dallas, TX, single family residence. How does Neville Longbottom get the Sword of Gryffindor? I recently read the final book of the series. At one point was the vault heist, where the goblin Griphook runs off with the Sword of Gryffindor. Yet near the end of the book, Neville Longbottom suddenly has the sword and uses it to defeat the snake Nagini.  How could this be possible? Griphook wanted the sword because it was goblin-made, so I doubt he would given it over to any non-goblin. How does Neville suddenly get the sword? I'm trying to make a command that creates a book that has many items with enchantments at level 1,000. However, I don't know why it keeps saying:     Data tag parsing failed: Unbalanced quotation:   {ench:[{id:0,lvl:1000}],Unbreakable:1,display:{Name:"Prot   It's supposed to say "Protection Armor", but it only shows "Prot" for some reason. This is the same with all of my other items. Here is the one part of the command that I've showed you:  {ench:[{id:0,lvl:1000}],Unbreakable:1,display:{Name:"Protection Armor"}} Create JSON using apex Testing random number generation I have a program which generates random numbers. How can I test if the random number generator is generating actual random numbers? What do I need to run a D&D 5E campaign? I have GM'd several RPGs before that are not D&amp;D (Fate, Deathwatch, Star Wars). We first tried to play D&amp;D using the 3.5 edition and it went horribly — too many books and too many options with no idea of where to start.  I have been told that 5E takes care of all that and is easier and more fun so I want to try that but I would like a definitive list of what I need.  I expect that the kinds of books we need divide up like this:   Rulebook for me as GM Rulebook for players Fluff for everyone Monster book for me as GM   Links to these would be helpful as we got very confused with the 3.5 books — who should use what books confused us.  What other things do we need to play a campaign? I expect things like:   Dice: what kinds and how many of each kind, roughly. Models and maps. Do we need these? Does 5E need models and a grid or can it be played without (which is preferred)?   Is there anything else that we need that I haven't anticipated? whether it be vs whether it is I brought the sentences from the speech about conversation tips.     They don’t just want to know about news and the weather.   They want to know about you.   So what are three things that you have going on right now, that you can talk about.   Whether it be school, whether it be a personal relationship, whether it be a hobby that you’re involved with.   My questions:     What is the difference in nuance between 'whether it is' and 'whether it be'?   Before posting this question, I googled, and some websites say 'whether it be' is subjunctive. I don't get why it is called 'subjunctive'. Because from what I know about subjunctive, it's supposed to be past of be verb.    If I say 'whether it should be' or whether it would be', is the meaning same? I enjoy going fast and my current bicycle tops too early, what kind of upgrades would I need to make to achieve a taller final gear? Motley fool says you can make $15,978 more per year with Social Security. Is this for real? The Motley fool has an ad campaign that says you can make $15,978 more per year on Social Security by doing 17 minutes of work using a legal loophole.  I don't want to link to their ad (although, you can find it by searching ).  What are they talking about here?  Is there any truth to this?  If someone could explain it to me without me having to watch the entire ad video or subscribe to their newsletter, I'd appreciate it.