Does the "field" in physics same as the "field" in mathematics? Which one those is more abstract in Nature?

There was a reason why I constantly failed physics at school and university, and that reason was, apart from the fact I was immensely lazy, that I mentally refused to "believe" more advanced stuff until I understand the fundamentals (which I, eventually, never did). As such, one of the most fundamental things in physics that I still don't understand (a year after dropping out from the university) is the concept of . No one cared to explain what a field actually is, they just used to throw in a bunch of formulas and everyone was content. The school textbook definition for a field (electromagnetic in this particular case, but they were similar), as I remember it, goes like:  An electromagnetic field is a special kind of substance by which charged moving particles or physical bodies with a magnetic moment interact.  A special kind of substance, are they for real? This sounds like the authors themselves didn't quite understand what a field is so they decided to throw in a bunch of buzzwords to make it sounds right. I'm fine with the second half but a special kind of substance really bugs me, so I'd like to focus on that. Is a field material? Apparently, it isn't. It doesn't consist of particles like my laptop or even the light. If it isn't material, is it real or is it just a concept that helps to explain our observations? While this is prone to speculations, I think we can agree that in scope of this discussion particles actually do exist and laws of physics don't (the latter are nothing but human ideas so I suspect Universe doesn't "know" a thing about them, at least if we're talking raw matter and don't take it on metalevel where human knowledge, being a part of the Universe, makes the Universe contain laws of physics). Any laws are only a product of human thinking while the stars are likely to exist without us homo sapiens messing around. Or am I wrong here too? I hope you already see why I hate physics. Is a field not material but still real? Can something "not touchable" by definition be considered part of our Universe by physicists? I used to imagine that a "snapshot" of our Universe in time would contain information about each particle and its position, and this would've been enough to "de" it but I guess my programmer metaphors are largely off the track. (Oh, and I know that the uncertainty principle makes such (de)serialization impossible — I only mean that I thought the Universe can be "defined" as the set of all material objects in it). Is such assumption false? At this point, if fields indeed are not material but are part of the Universe, I don't really see how they are different from  except for perhaps a more geeky flavor. When I talked about this with the teacher who helped me to prepare for the exams (which I did pass, by the way, it was before I dropped out), she said to me that, if I wanted hardcore definitions,  a field is a function that returns a value for a point in space.  Now this finally makes a hell lot of sense to me but I still don't understand how mathematical functions can be a part of the Universe and shape the reality.


I'm learning Python and I'm messing around with API calls and Json responses. I want to turn the response into objects. My approach is to iterate through the json response using nested loops and for each json object create a python object. The json response contains a number of families, and each family has a number of family members. The problem is that when I turn them into python objects, each family gets ALL the members from ALL the families. I guess it has something to do with the scopes in the loops, but I can't figure out the right way to approach this. All help would be appreciated: The json response: families_from_api = """{     "success":true,"data":[         {             "family":"Anderson","members":[                 {"name":"Roger","age":36},                 {"name":"Alice","age":"24"},                 {"name":"Sammy","age":12}             ]         },         {             "family":"Lindquist","members":[                 {"name":"Martin","age":52},                 {"name":"Lukas","age":"46"},                 {"name":"Anne","age":20}             ]         }     ] } """  # Pythonize the response families_info = json.loads(families_from_api) families = families_info['data']  The classes: class Member:     name = ""     age = 0  class Family:     name = ""     members = []  Iterating through the response and creating objects: # Array to store all families all_families = []  # Iterate through the response and turn into objects for family in families:     f = Family()     f.name = family['family']      for member in family['members']:         m = Member()         m.name = member['name']         m.age = member['age']         f.members.append(m)      # Append the created family object to an array     all_families.append(f)  Printing my objects: # Iterate through objects and print families and members for family in all_families:     print("Family name:", family.name, "has these members:")     for member in family.members:         print("Name:", member.name, "Age", member.age)  The result: Family name: Anderson has these members: Name: Roger Age 36 Name: Alice Age 24 Name: Sammy Age 12 Name: Martin Age 52 Name: Lukas Age 46 Name: Anne Age 20 Family name: Lindquist has these members: Name: Roger Age 36 Name: Alice Age 24 Name: Sammy Age 12 Name: Martin Age 52 Name: Lukas Age 46 Name: Anne Age 20

Is there any meaningful distinction between:  class A(object):     foo = 5   # some default value   vs.  class B(object):     def __init__(self, foo=5):         self.foo = foo   If you're creating a lot of instances, is there any difference in performance or space requirements for the two styles? When you read the code, do you consider the meaning of the two styles to be significantly different?


I would like to know why do I get two different results when I calculate $\int_\gamma ln(z) dz$ ,with $\gamma$ the unit cercle, when using two different branch cuts $[0,+\infty[$ and $]-\infty,0]$ ?  Thanks a lot,

When I take as a branch cut $]\!\,-\!\infty,0]$ for the complex logarithm, I get: $$\int_{\lvert z\rvert<1}\ln(z)\,dz=\int_{-\pi}^{\pi}\ln(e^{i\theta})\,i\theta \,d\theta=-2i\pi$$ whereas, when I take  $[0,+\infty[$ as a branch cut, I get:  $$\int_{\lvert z\rvert<1}\ln(z)dz=\int_{0}^{2\pi}\ln(e^{i\theta})\,i\theta \,d\theta=2i\pi$$ Does the integral of $\ln(z)$ depend on the branch cut we choose?


Problem:  Consider the inﬁnite Atwood’s machine shown below. A string passes over each pulley, with one end attached to a mass and the other end attached to another pulley. All the masses are equal to m, and all the pulleys and strings are massless. The masses are held ﬁxed and then simultaneously released. What is the acceleration of the top mass?   I don't know how to do this problem with infinite pulleys. If the tension in the topmost string is $T$ then I get, and $a_1, a_2$ be the acceleration of the first and second masses wrt.the first and second pulleys then I get,  $\frac{T}{2}-mg=ma_1$ and  $\frac{T}{4}-mg=m(a_2-a_1)$ but I dont know how to proceed. I am beginner at mechanics.  Please help.

I tried doing  just for fun. It is reproduced as follows:          (I'm not allowed to post the entire problem here since I'm a new user.)  Here are my equations:  $$T - mg = ma$$ (equation 1)  $$Mg - T = Ma$$  (equation 2)  (Upper case "M"  used for infinite series of masses on the right arm of the first pulley. Lower case "m" for the small, single mass on the left arm.)  algebra is as follows:  $$Mg - (ma + mg) = Ma$$ $$g (M - m) = a (M + m)$$ $$a = g (M - m) / (M + m)$$   Here is my reasoning to get final answer:   The limit of $a$ for large $M$ goes to $g$. Therefore, acceleration of the top mass is $g$. However, the correct answer is $g/2$. Why does my reasoning get the wrong answer? Any ideas?    (Please excuse the formatting, I'm a newbie here).


Here we have a scenario where a Service account , added under security as sysadmins for windows login, going to have its password change as per windows policy.  Since windows team, server admins are going to change the password, where should i check or what pre-activity should i consider before the password is changed.  This account (windows domain) is running the SQL services as well.

As part of a security policy, the company I work for has given me the task of changing the sa's and SQL Server Agent service accounts' passwords for several instances.  What's the possible impact of doing this? Is there anything in particular I should watch out for? Is there any whitepaper, guide or even blog post about this kind of task? What kind of 'backup' plan should I have in place in case anything goes wrong?  Any guidance is appreciated.


radius = float(input()) print('Enter the radius:', radius) pi = 3.1415 volume = (4 / 3) * pi * radius * radius * radius print('The volume is ', volume)   From this the expected value is   Enter the radius: 10.0 The volume is 4188.666666666667  However, I get the volume as 4188.666666666666  How do I fix this?

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


I am getting aerror while concatenating query for SQL in PHP     $query = "INSERT INTO bookings (date, start, userId) VALUES ('$booking_date','$booking_time','$_SESSION['userIdSession']');";   The single quotes '' in $_SESSION['userIdSession']        are causing this problem.  What is the right way to concatenate this string without getting error?  (I am beginner in PHP, do not down vote me)

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


With reference to this currently open question   At the time of writing, it has 3 close votes yet has 7 question upvotes and the single answerer (11 upvotes) will have been awarded the enlightened badge (silver).  Therefore in the opinion of many (i) the question adds value and (ii) the answer adds value.  As a staring point for discussion, I suggest that 5 net question upvotes (and perhaps 5 answer net upvotes) should be enough to keep a question permanently open. Let's haggle over the numbers though. Thoughts?

Questions can be closed or marked as duplicates.  What does it mean for a question to be "closed"? What does it mean for a question to be marked as a "duplicate"? Who can close a question? What are the reasons for closing a question ? Is closure the end of the road for a question? When are closed questions eligible for deletion?   Related        For more information, see "" in the .


How did Stannis Baratheon get his huge mounted army north of the Wall? This logistical feat is not explained.  Assuming an army of 25,000, it would be hugely time-consuming to go through the Wall's gates.

If Mance Rayder had to attack Castle Black to use the tunnel to get through the Wall and get out of the north, how did Stannis get his army across the Wall into the north without anyone knowing? If there was another way over the Wall wouldn't the wildings go that way too?


Yesterday, my friend's laptop fell down on the floor. Because it is quite robust we though that it won't leave a mark. But we were wrong. Upon boot strange noises began to come out of the inside of the laptop. Then, the boot logo appeared as normal. But continuing onward, we were met with this message:     Intel UNDI, PXE-2.1 (build 083) Copyright (C) 1997-2000  Intel Corporation  This product is covered by one or more of the following patents: US6,570,884, US6,115,776 and US6,327,625  Realtek PCIe GBE Family Controller Series v2.57 (08/27/13) PXE-E61: Media test failure, check cable PXE-MOF: Exiting PXE ROM    Then, the BIOS error audio began bleeping like crazy and wouldn't stop until we turned the laptop off.  I think it is safe to conclude from the scratching noises that some hardware was damaged and that a technical support will be needed. I am only a bystander, but even so, I am curious what are the possible reasons for this error. Please, satiate my thirst for knowledge.  And just a little bonus for my friend: I am convinced that we cannot restore the computer by ourselves, but if anyone does have a solution, which doesn't include taking the laptop to repair (I doubt), please tell us. We are very grateful for your help.

My computer no longer boots Windows or the installed operating system. Instead, I may get this error:  PXE-E61: Media test failure, check cable -or- Check cable connection!  PXE-M0F: Exiting PXE ROM.   and/or one of the following messages or similar:  Operating System not found  No boot device available- No bootable devices--strike F1 to retry boot, F2 for setup utility  No bootable device -- insert boot disk and press any key  No Boot Device Found. Press any key to reboot the machine  Default Boot Device Missing or Boot Failed  Reboot and Select proper Boot device or Insert Boot Media in selected Boot device   What does this mean and what can I do?     This question comes up often and the answers are usually the same. This post is meant to provide a definitive, canonical answer for this problem. Feel free to edit the answer to add additional details.


I have this piece of HTML:  LG ha tolto i veli al nuovo&nbsp;LG Chocolate, nome in codice BL40, un cellulare dalla forma insolita e dai contenuti tecnologici molto avanzati.&nbsp;A prima vista colpisce subito l'imponente schermo LCD da&nbsp;4 pollici&nbsp;e risoluzione di 800x345 pixel, che corrispondono a un formato di&nbsp;21:9. Questo rapporto d'aspetto permette di vedere a tutto schermo i film in questo formato, ma non solo: a beneficiarne è infatti anche la navigazione sui siti Internet. Grazie poi alla funzionalità&nbsp;Dual Screen UI&nbsp;è possibile visualizzare contemporaneamente sullo schermo due tipi di contenuti differenti.   I'm using regular expression to strip the span. I must strip the span with the exact match, because I'm processing about 12.000 document.  I'm using:  $string = preg_replace( '/(.*?)<\/span>/s', '
$1
',$string);   It doesn't work, I try also with Rubular. Why?

I'm looking for a single line regex which does the following:  Given a HTML tag with the "name" attribute, I want to replace it with my own attribute. If that tag lacks the name attribute, I want to implant my own attribute. The result should look like this:   =>   =>    Can this be done with a single line regex?


If earth generates magnetic field does it attract metal objects at the surface of the planet and make them heavier?

Non-metal objects are attracted to the Earth due to gravity. So the weight of non-metal objects can be only dependent on their mass.   On the other hand metals can be attracted to the Earth's magnetic field, with the Earth acting as a giant magnet; causing metals to weight more than they normally should.   In other words the weight of metals and magnetic objects would be the sum of the magnetic force plus the gravitational force, is that correct?  If that effect is true, would it be more clear as we go closer to the magnetic poles, and metals would weigh different in different locations on Earth?


I have a fresh install of Ubuntu 18.04.1, and am trying to install python3-venv.  I have tried all of the following:  sudo apt install python3-venv sudo apt install python3.4-venv sudo apt-get install python3-venv sudo apt-get install python3.4-venv sudo apt-get install -y python3-venv sudo apt-get install -y python3.4-venv   All of the above with 3.4 result in Unable to locate package python3.4-venv.  All of the above with 3 result in:  Package python3-venv is not available, but is referred to by another package.   This may mean that the package is missing, has been obsoleted, or is only available from another source. E: Package 'python3-venv' has no installation candidate   I had the same problem with python3-pip, but managed to install it by curling the source.  I think this fact is a key detail to the problem, but I don't know what problem that detail points to.  Thanks in advance :)

How do you use terminal to enable Universe source? Or any those 4 from Software Sources: Main, Universe, Restricted, Multiverse Main is on by default and Restricted is on if durring Ubuntu installation i tick Enable Restricted Formats. Answer with line where version checked so it auto detects it. Like command I know for partner but that goes to Other Software tab sudo add-apt-repository "deb http://archive.canonical.com/ $(lsb_release -sc) partner"


I had a typo and wrote $$ in a bash script (as argument to echo).  It printed a number (1979).  I tried many times, and all of them printed the same number, so I thought it might have to do with the Unix epoch.  I didn't find any information about it in the bash manual, or in the internet at all.  Then I tried on a basic sh; it printed a different number, 5755, and after closing and opening a new sh, it printed a slightly different number. What is that variable supposed to hold?  What is the meaning of that number?

there is a script I evolved with it, it has line of command like below :  mytemp=`echo ${sourcedir}|awk -F/ '{printf "/%s/tmp",$2}'`/`basename $0`-$1.$$   at the last of the command we see $$ that produces a number. when I use echo $$ in bash I also see a number like bellow:   #echo $$  23019   what exactly is this number, and what is $$?


I'm a beginner on blender and I'm still trying my best to understand nodes, UV editing and basically everything texture related. I am trying to make a story dice which means I am trying to add transparent images to each side of the dice. I know how to do the shrink-wrap method but am trying to learn the proper way of adding materials to an object. I have a feeling it will probably be quite an obvious process but I have been trying at this for hours and am getting sort of desperate..   From the images you can see my attempts at trying to use mix nodes so I can have my transparent images show through the base color, but I cant seem to get more than 1 different image type per face, they either are all the same image or simply don't show. I hope this makes sense and I GREATLY appreciate any help that comes my way! (also why do i have so many materials, how do i delete them!?)

I'm designing this animal-type creature, and want to add a transparent .png image to its face with the face features (object has a subsurf). On the left is the image with the features, on the right is the part of the object where I want it to be.    I tried to import the image as a plane, but matching the shape of the plane with the face didn't work, and the lines of the face left shadows on the head, and could be seen as a different object from some angles (although it's the closest I've gotten yet). It looked like this:    So , I tried selecting the faces of the head that the features should go over, and create a new material for it. Unfortunately, since the .png is transparent, the result produced was this:    (where it's impossible to tell the transparency from a black background default color, and where I wouldn't know where to start to adjust size and position).  I also tried UV mapping, but then the whole object became black with the features repeated all over.   Is it something I have to go into Nodes for? I'm kind of stuck here. Creating a new material and applying it is simple, but applying a material that is an image is a bit more complex it seems... Ideally, I would reproduce the same technique for the adhesive bandage on its arm (seen on the right of image 1).


Lemma: Suppose that $A,B \subseteq X$ are connected and $A \cap B \neq \emptyset$ , then $A \cup B$ is connected.  How would I go about proving this? I think I understand the consequences of the lemma and it seems sort of obvious why it would be true, but I can't figure out how to prove it.   Any help would be great.

Let $\mathscr{F}$ be a collection of connected subsets of a metric space $M$ such that $\bigcap\mathscr{F}\ne\emptyset$. Prove that $\bigcup\mathscr{F}$ is connected.   If $\bigcup\mathscr{F}$ is not connected, then it can be partitioned into two disjoint, non-empty subsets $A,B$. Let $x$ be a point in $\bigcap\mathscr{F}$. Then either $x\in A$ or $x\in B$. I don't know where to go from here.


To show that two sets are equipotent, we must find a bijection between the two. Proof $\mathbb{N}=\{1,2,3,4,...\}$ Let $X \subseteq \mathbb{N}$ with $|X|=\infty$. So, for some $x \in \mathbb{N}, X = \{x,x+1,x+2,x+3,...\}$ Define $f: \mathbb{N} \to X$  with $f(1)=$ min$(X)$ and for each $n \geq 2 \in \mathbb{N},$ let $f(n)=$ min$(X)+(n-1)$. One-to-one: Suppose $f(m)=f(n)$ min$(X)+m - 1 =$ min$(X) +n - 1$ $m-1=n-1$ $m=n$ Onto: Again, $f(n)=$ min$(X) + n - 1$ $n=f(n) -$ min$(X) +1 \in \mathbb{N}$ Note: since $X\subseteq \mathbb{N},$ min$(X) \geq$ min$\mathbb{(N)}$ for any chosen subset $X$. This clears up any issues regarding closure under subtraction when testing for surjectivity. Since $f$ is one-to-one and onto, $f$ is a bijeciton. $|X| = |\mathbb{N}|$ $\square$

I want to prove that if $A$ is an infinite subset of the natural numbers, then it is countable.   I thought of an informal proof: put the elements of $A$ in increasing order. Then associate the smallest to $1$, the second smallest to $2$, the third smallest to $3$ and so on.   I've tried to formalise this proof in this way: consider the sequence $$ \begin{cases} A_1=A \\ A_n=A_{n-1}-\min{A_{n-1}}\end{cases}$$ The function $f(\min{A_n})=n$ has domain $A$ and codomain $\mathbb{N}$ and is a bijection, therefore $A$ is countable.  My questions are the following:   Is what I wrote correct? If so, how do you prove that $f$ is actually a function from $A$ to $\mathbb{N}$ and is also a bijection?


I don't assume the Rule of Two was followed so strictly, since Sith are the bad guys, they would not always play by the rules... But it seems that it was Sidious's way to have only one apprentice at a time.  As shown in RotJ, the Emperor had no problem in letting Luke kill Vader... He even encouraged him to do so, so he would take his father's place at his side... He did the same when Anakin fought Dooku in Episode III...  Had things went differently, and Luke was turned to the dark side, would Sidious just kill Vader, so that it would only have two Sith at a time?  Is there any material that exposes the Emperor's ultimate intentions in his plan of bringing Luke to the dark side, regarding this matter of slaughtering Vader?

Provided there was  in place, was Sidious going to replace Vader with Luke? Or, was there something else in his mind (like what he did with Darth Maul in Star Wars: The Clone Wars)?


I got a window on top of all others saying: "You'll need a new app to open this microsoft-edge". It can be selected (the screen grab for the image below recognises that this is the current window), but does not seem to respond. The OK button is greyed out, it cannot be moved off screen and does not respond to Alt-F4.   It is not on the Alt-Tab list of things. Clicking outside the window works as normal, ie. other programs respond but this one stays. As it has no title, it isn't immediately obvious which process it belongs to (some internal one, which perhaps I shouldn't terminate anyway?)  So I think somehow I got Windows to try opening Edge with another program..(?), more interestingly, how do I get rid of the window? Thank you.

A spurious dialog box (informative, no?) keeps popping up on reboot.  What's an easy way to figure out what clearly-very-well-coded-piece-of-software threw it up there?  I've reduced the startup list to a minimal list to no avail.


Scenario:  You ride in a train, you have this helicopter toy. The train is not yet running when you flew your helicopter on a constant altitude (say 1 meter above the train's floor).  Question: What will happen on the flying helicopter toy when the train accelerates?   Will it stay relative to you and the train? Will it move backward relative to you and the train and bump to the rear part of the train? Will it move backward relative to you and the train for few seconds and then stay? Any other thoughts?

A fly is flying around in a car, the fly never touches any surface in the car only fly’s around in the air inside the car. The car accelerates. does the fly slam in to the rear window. or does the fly continue to fly uninterrupted?


I am looking for a SQL query to get sql row data to a column.   SQL Table Data  CustomerId     Name             Type        FoodName =============   =============   =========   ========== C0001           Thomas          BREAKFAST   Milk C0001           Thomas          BREAKFAST   Bread C0001           Thomas          BREAKFAST   Egg C0001           Thomas          LUNCH       Rice C0001           Thomas          LUNCH       Fish Curry C0001           Thomas          LUNCH       Lessy C0002           JOSEPH          BREAKFAST   Bread C0002           JOSEPH          BREAKFAST   Jam C0002           JOSEPH          BREAKFAST   Tea   The above is the SQL Table Data and I need this data in following format. Can anybody help me to create a SQL Qyery to get below output ?  CustomerId      Name            BREAKFAST           LUNCH    ============    =============   ================    ==========  C0001           Thomas          Milk, Bread, Egg    Rice, Fish Curry, Lessy  C0002           JOSEPH          Tea,Bread, Jam   Please help me to create SQL Query to get the above output.  I Tried the following query  with DietList(CustomerId,Name,BREAKFAST, DINNER) as ( select distinct CustomerId 'CustomerId', Name as 'Name' ,(     select a.foodName + ',' as [text()] from      (select AdmnNo,foodName from DietCard) as a          where c.CustomerId = a.CustomerId and c.DietSchedule = 'BREAKFAST' and  convert(varchar, [c.ScheduleDate], 112) = '20180402'      for xml path('')         ) 'EVENINGTEA' from DietCard  ) ,(     select a.foodName + ',' as [text()] from      (select AdmnNo,foodName from DietCard) as a          where c.CustomerId = a.CustomerId and c.DietSchedule = 'DINNER' and  convert(varchar, [c.ScheduleDate], 112) = '20180402'      for xml path('')         ) 'DINNER' from DietCard  ) select * from DietListList where BREAKFAST is not null or DINNER is not null   Thanks in Advance.

Consider a database table holding names, with three rows:  Peter Paul Mary   Is there an easy way to turn this into a single string of Peter, Paul, Mary?


I had some intermittent trouble with the internal EEPROM of a dsPIC. Every so often, some value in the EEPROM would be found zeroed out on power-on. I tracked the problem down to when the chip lost power after the erase step of the write cycle, but before the write had completed. It was all about the timing of the power-down relative to the firmware execution, which was (in normal operation) random. I solved this by adding a buffer section to my EEPROM, to ensure that an incomplete write-cycle could be completed on restoration of power. I had to turn EEPROM writes into an atomic operation.  (For further detail, my buffering technique defines an area of persistent memory that consists of three fields: address to write to, data to be written, and a READY flag. A "write" consists of four steps: write to buffer, set READY flag, write from buffer, clear READY flag. On power-up, you check the READY flag. If it's set, execute whatever's in the buffer. This worked well in internal EEPROM.)  Now I'm using a different dsPIC without internal EEPROM, and I'm trying to use an  to store persistent data. I'm wondering if I should have similar concerns. Should I be worried that my external EEPROM chip will power down mid-write and lose data, and write a fix for this in my firmware like I did for internal EEPROM? Or does the chip itself guarantee atomic write operations?

I had some intermittent trouble with the internal EEPROM of a dsPIC. Every so often, some value in the EEPROM would be found zeroed out on power-on. I tracked the problem down to when the chip lost power after the erase step of the write cycle, but before the write had completed. It was all about the timing of the power-down relative to the firmware execution, which was (in normal operation) random. I solved this by adding a buffer section to my EEPROM, to ensure that an incomplete write-cycle could be completed on restoration of power. I had to turn EEPROM writes into an atomic operation.  Now I'm using a different dsPIC without internal EEPROM, and I'm trying to use an  to store persistent data. I'm wondering if I should have similar concerns. Should I be worried that my external flash chip will power down mid-write and lose data, and write a fix for this in my firmware like I did for internal EEPROM? Or does the chip itself guarantee atomic write operations?  For further detail, my buffering technique defines an area of persistent memory that consists of three fields: address to write to, data to be written, and a READY flag. A "write" consists of four steps: write to buffer, set READY flag, write from buffer, clear READY flag. On power-up, you check the READY flag. If it's set, execute whatever's in the buffer. This worked well in EEPROM, but I'm not sure if it will work well in flash.


I get the strangest result when I multiply 1.09 and 12. Actually 13.080000000000002 instead 13.08!!! What causes this? nd what is the solution  console.log(1.09*12);  Regards.

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


In a file with lots of lines I want to delete lines that starts with HERE IT IS.  How can I do this using only command-line tools?


I have images(Jpg, gif ,png etc..) local hard disk. What I need to read all file information such as location details latitude longitudes or location name and photos created date  each images. Please help me how do I read location details and date.  This is my C# code it not display location details or created date   string directory = (@"C:\Photos");  var AllImages = Directory.GetFiles(directory, "*.jpg",                                    SearchOption.AllDirectories)                          .Select(Image.FromFile).ToList()   This is one of my photo example  .

I would like to write a small program in C# which goes through my jpeg photos and, for example, sorts them into dated folders (using MY dating conventions, dammit...).   Does anyone know a relatively easy way to get at the EXIF data such as Date And Time or Exposure programatically? Thanks!


Sometimes when I'm researching on a software issue (i.e. a bug that I most likely created), I google a lot and so have a lot of tabs open in FireFox. I don't use IE :)  But FireFox only allows me to save the open-tabs for the last session. Is there a way that I can sort of command FireFox to obey => for this FireFox main window containing all these open tabs, save the session as name "researching on bug #232 -- file is not saving" so that I can come back later and click on a button to have all those tabs open up again.

I'm looking for some Firefox (4 or 5) extension to save a group of tabs (better if can be done directly in Panorama view). What I mean by "Save tabs" is not to restore them when Firefox starts.   I always have the browser opened and a LOT of tabs (work and personal life related) eating my RAM. So when I'm not working, I would want a way to save those tabs but keep them closed while I still use Firefox. So when I have to start working again, I will restore that saved tabs back again.  I know I could use something like Read It Later, but I really need a way to say "hey, save this group of tabs and close them". RIL makes me do it per tab, which is annoying since I'm used to have A LOT.


How to remove duplicate items from a list using list comprehension? I have following code:  a = [1, 2, 3, 3, 5, 9, 6, 2, 8, 5, 2, 3, 5, 7, 3, 5, 8] b = [] b = [item for item in a if item not in b]   but it doesn't work, just produces identical list. Why its producing an identical list?

Is there a built-in that removes duplicates from list in Python, whilst preserving order? I know that I can use a set to remove duplicates, but that destroys the original order. I also know that I can roll my own like this:  def uniq(input):   output = []   for x in input:     if x not in output:       output.append(x)   return output   (Thanks to  for that .)  But I'd like to avail myself of a built-in or a more Pythonic idiom if possible.  Related question:


I know this may sound too simple or maybe too absurd to discuss, but I am having a hard time visualizing a point in space! In Euclid's Elements a 'Point' is defined as Something which has no part. Now, any geometrical figure viz. Line Segment,Triangle,Square etc. can be said to be composed of points. No matter how small we try to make a point, it still has some size/dimension. So,how can these infinitude of points add up to give the length/perimeter of the above mentioned figures,when according to Euclid,these have NO PART?

Everyone knows that a point on any plane has zero magnitude, height, width, or volume. A line is a collection of points, and a plane is a collection of lines, while a cube is a collection of planes and so forth.  How is it then that any line, surface or cube can be made of points that have no magnitude area etc.


I want to call print preview from button click in angular 2. I need to support IE11 users. Chrome automatically open print preview on print but IE11 opens only print window.    In template:  <button (click)="print()">print</button>   In ts file:  print(){   print() //lib.es6.d.ts }   How can i open print preview in IE11?

I have a page that is supposed to launch the Print Preview page onload.  I found this:  var OLECMDID = 7; /* OLECMDID values: * 6 - print * 7 - print preview * 1 - open window * 4 - Save As */ var PROMPT = 1; // 2 DONTPROMPTUSER var WebBrowser = '<OBJECT ID="WebBrowser1" WIDTH=0 HEIGHT=0 CLASSID="CLSID:8856F961-340A-11D0-A96B-00C04FD705A2"></OBJECT>'; document.body.insertAdjacentHTML('beforeEnd', WebBrowser); WebBrowser1.ExecWB(OLECMDID, PROMPT); WebBrowser1.outerHTML = "";   But...   it does not work in FireFox. it's kind of ugly.   Is there a better way for IE or a way that works for FireFox?


Physicists say that there are four fundamental forces in the universe: gravity, electromagnetic, and the other two. But when the gravitational phenomena were explained by the General theory of relativity, the belief that gravity is a force becomes weak. So the fundamental question is that if one day someone explained the phenomena associated with the other forces in a similar way as gravity, would they then still be called forces or would they be instead called, for example, curvature in some "other thing"?

Is there an answer to the question why there are only four ?


Can't access the snap apps from terminal using Ubuntu 19.10  $ vlc     Command 'vlc' is available in '/snap/bin/vlc'     The command could not be located because '/snap/bin' is not included in the PATH environment variable.   I manually linked the .desktop file to show vlc in the app menu but can't do the same with ytd. is there any permanent solution for opening vlc and ytd from terminal itself.    $ youtube-dl Command 'youtube-dl' is available in '/snap/bin/youtube-dl' The command could not be located because '/snap/bin' is not included in the PATH environment variable.

I have successfully installed snapd on Ubuntu 16.04 but while running the app, say snap run hello I am getting the following error:  cannot create lock directory /run/snapd/lock: Permission denied  I have tried the following   sudo apparmor_parser --replace --write-cache /etc/apparmor.d/usr.lib.snapd.snap-confine.real --cache-loc /etc/apparmor.d/cache   but did not work even after restart. I am not able to run any snap app though able to install any apps.  The snapd service is also running. But still even after reboot, the problem remains the same.


I am working on a model in r and below is the output of confusionMatrix I got-                Accuracy : 0.7952                           95% CI : (0.7775, 0.8122)    No Information Rate : 0.8388              P-Value [Acc > NIR] : 1                                  Kappa : 0.1149           Mcnemar's Test P-Value : 5.345e-09                    Sensitivity : 0.18605                     Specificity : 0.91229                  Pos Pred Value : 0.28959                  Neg Pred Value : 0.85363                      Prevalence : 0.16120                  Detection Rate : 0.02999            Detection Prevalence : 0.10356               Balanced Accuracy : 0.54917            Can someone explain me what is the difference between P-Value [ACC > INR] : 1 and Mcnemar's Test P-Value in the result above.

I want know the formulas for the information highlighted in the confusion matrix in the picture below:


I've got a dual-boot of Ubuntu and Windows and due to some file system inconsistency Ubuntu won't load. It always runs a file system check and then switches to emergency mode. This is a list of errors from the journal:  -- Logs begin at Čt 2016-10-20 16:27:28 CEST, end at Čt 2016-10-20 16:29:24 CEST. -- kernel: Error parsing PCC subspaces from PCCT systemd-fsck[506]: fsck failed with error code 4. systemd[1]: Failed to start File System Check on /dev/disk/by-uuid/115d2332-e953-48a1-a0c8-05fef157d207.   Trying to fix the Error Parsing PCC Subspaces I've disabled hiberboot in Windows but it didn't help.  I've also tried the most voted suggestion in this thread with no success:    Fsck said:   /dev/sda1 clean   Fdisk output:  Disk /dev/sda: 465.8 GiB, 500107862016 bytes, 976773168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disklabel type: dos Disk identifier: 0x38034de7  Device     Boot     Start       End   Sectors   Size Id Type /dev/sda1            2048 453787647 453785600 216.4G 83 Linux /dev/sda2       968970238 976771071   7800834   3.7G  5 Extended /dev/sda3  *    453787648 556187647 102400000  48.8G  7 HPFS/NTFS/exFAT /dev/sda4       556187648 968968191 412780544 196.8G 83 Linux /dev/sda5       968970240 976771071   7800832   3.7G 82 Linux swap / Solaris  Partition 2 does not start on physical sector boundary. Partition table entries are not in disk order.   Would you know about any solution to this?  EDIT:  After fsck on sda4, it seems to work fine.  blkid output:  /dev/sda5: UUID="e8f7fdb0-1024-496b-aaba-376aeb30849b" TYPE="swap" PARTUUID="38034de7-05" /dev/sda1: UUID="9fa78f27-9b26-4f92-bd20-180ed6903220" TYPE="ext4" PARTUUID="38034de7-01" /dev/sda3: UUID="249E367E9E364916" TYPE="ntfs" PARTUUID="38034de7-03" /dev/sda4: UUID="115d2332-e953-48a1-a0c8-05fef157d207" TYPE="ext3" PARTUUID="38034de7-04"

My computer booted to a black screen with this error message.  Welcome to emergency mode! After logging in,type "journalctl -xb" to view    system logs, "systemctl reboot" to reboot, "systemctl default" or ^D to    try again to boot into default mode.   journalctl -xb snippet (what I think is wrong):  -- Unit systemd-fsckd.service has begun starting up. juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: /dev/sdb1 contains a file system with errors, check forced. juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: /dev/sdb1: Inodes that were part of a corrupted orphan linked list found. juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: /dev/sdb1: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY. juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: (i.e., without -a or -p options) juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: fsck failed with error code 4. juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: Running request emergency.target/start/replace juli 09 15:40:16 kim-SSD-Sationary systemd[1]: systemd-fsck-root.service: main process exited, code=exited, status=1/FAILURE juli 09 15:40:16 kim-SSD-Sationary systemd[1]: Failed to start File System Check on Root Device. -- Subject: Unit systemd-fsck-root.service has failed -- Defined-By: systemd -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel --  -- Unit systemd-fsck-root.service has failed. --  -- The result is failed. juli 09 15:40:16 kim-SSD-Sationary systemd[1]: Unit systemd-fsck-root.service entered failed state. juli 09 15:40:16 kim-SSD-Sationary systemd[1]: systemd-fsck-root.service failed. juli 09 15:40:16 kim-SSD-Sationary systemd[1]: Starting Remount Root and Kernel File Systems... -- Subject: Unit systemd-remount-fs.service has begun start-up -- Defined-By: systemd -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel   I ignored other errors like: ACPI PCC probe failed, nvidia not proprietary, etc.  I can access my PC by pressing Ctrl+D , but it is annoying.


Every single mirror is missing the Quantal dists.  NOTICE:  Before you comment, I do realize 12.10 is in End of Life status!  But to totally restrict further usage?  Unacceptable!

Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc


I want to install it on my old desktop PC. here is it's specs:   CPU: Intel Pentium 4@2.4GHz RAM: 736 MB VRAM: 256MB HDD: 120GB   I can install the following OSes on it:   Windows Vista Home Basic w/SP2 Mac OS X v.10.5.8 "Leopard" Ubuntu 14.04 LTS?

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


I've been trying to use the spy library to magnify a part of my plot, but I don't really understand how it works, and I can't find a manual/tutorial anywhere.  Right now I am doing something based on  for the magnification part, although not exactly what I was looking for, might do the trick.     However, my question is how exactly do I get the "x 2000" line, along with the second plot?

Is there a way to draw a sort of connection between subplots in TiKz/pgfplot, like in this ? I'm looking to achieve something like this:    But I would need to draw the "x 2000" line between the plots.  EDIT: So right now I have something like this:    Coming from my main.tex:  \input{aipcheck}  \documentclass[final]{aipproc}  \layoutstyle{8x11single} \usepackage[utf8]{inputenc} \usepackage{algorithm2e} \usepackage{color} \usepackage[usenames,dvipsnames]{xcolor} \usepackage{cleveref} \usepackage{pgfplots}  \pgfplotsset{ tick label style={font=\tiny}, %axis numbers label style={font=\small}, %axis labels legend style={font=\tiny} }  \begin{document}  (...)  \begin{figure}     \centering     \newlength\figureheight      \newlength\figurewidth      \setlength\figureheight{5cm}      \setlength\figurewidth{5cm}     \input{figs/_ddmp2d.tikz} \label{fig2D} \end{figure}   with _ddmp2d.tikz, originally created from matlab2tikz, but already modified, containing:  % This file was created by matlab2tikz v0.3.3. % Copyright (c) 2008--2013, Nico Schlömer <nico.schloemer@gmail.com> % All rights reserved. %  % The latest updates can be retrieved from %   http://www.mathworks.com/matlabcentral/fileexchange/22022-matlab2tikz % where you can also make suggestions and rate matlab2tikz. %  %  %   \begin{tikzpicture}  \begin{axis}[% width=\figurewidth, height=\figureheight, scale only axis, xmin=0, xmax=15, xlabel={Number of iterations}, ymin=0, ymax=16000000000000, name=plot1, after end axis/.append code={\coordinate (a) at (axis description cs:1,0);}]  \addplot [ thick, color=red, dash pattern=on 1pt off 3pt on 3pt off 3pt, forget plot ] table[row sep=crcr]{ 1 15841000000000\\ (...) 15 25160000000\\ }; \addplot [ thick, color=black, dashed, forget plot ] table[row sep=crcr]{ 1 15841000000000\\ (...) 15 52501000000\\ }; \addplot [ thick, color=blue, dotted, forget plot ] table[row sep=crcr]{ 1 15841000000000\\ (...) 15 5324200000\\ }; \addplot [ thick, color=green, solid, forget plot ] table[row sep=crcr]{ 1 15841000000000\\ (...) 15 551920000\\ }; \addplot [ thick, color=green, solid, forget plot ] table[row sep=crcr]{ 3 0\\ 3 16000000000000\\ };  \addplot [ thick, color=blue, dotted, forget plot ] table[row sep=crcr]{ 4 0\\ 4 16000000000000\\ }; \addplot [ thick, color=black, dashed, forget plot ] table[row sep=crcr]{ 5 0\\ 5 16000000000000\\ }; \addplot [ thick, color=red, dash pattern=on 1pt off 3pt on 3pt off 3pt, forget plot ] table[row sep=crcr]{ 8 0\\ 8 16000000000000\\ }; \end{axis}  \begin{scope}[xshift=5cm] \begin{axis}[% width=0.35\figurewidth, height=\figureheight, scale only axis, xmin=995, xmax=1000, xtick={997,998,999,1000}, xticklabels={$997$,$998$,$999$,$1000$}, ymin=0, ymax=8000000000, at=(plot1.right of south east), anchor=left of south west, yticklabel pos=right, axis x discontinuity=crunch, after end axis/.append code={\coordinate (b) at (axis description cs:0,1);} ] \addplot [ thick, color=red, dash pattern=on 1pt off 3pt on 3pt off 3pt ] table[row sep=crcr]{ 995 6093100000\\ 996 6093100000\\ 997 6093100000\\ 998 6093100000\\ 999 6093100000\\ 1000 6093100000\\ };  \addplot [ thick, color=black, dashed ] table[row sep=crcr]{ 995 1577100000\\ 996 1598000000\\ 997 1598500000\\ 998 1628600000\\ 999 1631000000\\ 1000 1595900000\\ };  \addplot [ thick, color=blue, dotted ] table[row sep=crcr]{ 995 2592000000\\ 996 2591900000\\ 997 2591700000\\ 998 2591600000\\ 999 2591500000\\ 1000 2591400000\\ };  \addplot [ thick, color=green, solid ] table[row sep=crcr]{ 995 391810000\\ 996 391810000\\ 997 391810000\\ 998 391810000\\ 999 391810000\\ 1000 391810000\\ };  \end{axis} \draw[gray] (a) -- (b) node[pos=0.5,sloped,fill=white] {$\times$2000}; \end{scope}  \end{tikzpicture}%


My wife and I want to visit India and decided to use Skyscanner.net as we usually do.  We obviously want to purchase our tickets together, and not separately.  If we set the number of travellers to 1, we get a price and then if we change the number of travellers to 2, we get a different, more expensive price.  Why? Is it a problem with Skyscanner?

I'm looking for tickets in despegar.com (a travel website for the American continent) and found out that a flight for just one person was about USD $350 incluiding all taxes, and I did the exact same search but instead of 1 person I chose 2 and the price for both tickets was USD $1200 (USD $600 each).  I thought this could be an error in the website, so I tried diferent dates and destinations getting the similar results.  Therefore I'm wondering if it is cheaper to buy airline tickets separately?   PS: The market price for the ticket I mentioned in the above example is about USD $600, so I'd love to take advantage of the USD $350 deal, but I'm afraid I might not find another ticket for my partner in the same flight.


Given the sentence:     The password must be at least 8 characters long, contain at least one lower-case and one upper-case case letter(s) and a digit.   Should the word "letter(s)" be in singular or plural? Why?  EDIT: To avoid discussion on the password policies, please consider another example:     Today I've seen one yellow, one blue and one green bird(s).

In other words, which sentence is correct?  At least one of them is not coming. At least one of them are not coming.


When you are standing in a running train if you jump means will you be in same place or will you be in front or back?

Why is it that if I'm sitting on a seat on a bus or train and its moving quite fast, I am able to throw something in the air and easily catch it? Why is it that I haven't moved 'past' the thing during the time its travelling up and down?


I looking for the name of one of Asimov's short stories, where the world ends and all dead people start coming out of their graves and start talking to their relatives.  I know some kind of celestial herald or angel is involved, but I don't remember much more.

This was a short story I read in the mid-90s in New York City, possibly in a digest like Asimov's or SF&F.  I remember two angels, at least one a seraph, conversing in space. They were in the solar system, hovering in the vicinity of Earth. They were very large and immaterial or intangible. At one point, one of the angels idly beats his wings, and one of them passes bodily through Mars.  They venerated God. When God's name is mentioned, in reverence, one of the angels (the senior one?) covers his face with two of his six wings.  What sticks in my mind is that at one point, God speaks, and his voice was described as infinitely small (or infinitely far away), and yet infinitely clear. This was probably an allusion to the "still, small voice" of the Bible, though I didn't know it at the time (so that's probably why the idea that the voice of an omniscient, and therefore utterly confident, being could be both infinitely small and clear struck me so, and stayed with me).  I have a vague sense there was at least one human character from Earth, the protagonist, that was involved, and the two angels were concerned with, but unfortunately I can remember nothing of the plot or premise.  Does anyone know what story this was?


If I'm asking a work-related question on StackExchange, I might find that one of my co-workers is more qualified to clarify and expand the question than I am. It might even be the case that the company wants to retain the ability to edit a question once I have left. I'm not sure if this is an appropriate use of the community wiki, as that would allow anyone to edit the question, even though it may be fairly specific to our company.  Is there a way to transfer ownership of a question so that someone else can edit it (without having to have their edits approved if they have less than 2,000 reputation), accept answers etc.?

Example: I have a two accounts, one main and one smaller. I create a great post on the mini, and want to move it to the main. Thus, my main can be attributed to the great post without merging the mini to the main.  Is it possible to move some posts (Q or A) from one user to another, without merging everything? (Obviously, with proof that both accounts have permitted this action)  If not, can this feature be considered?


I have always had issues with curved surfaces, like the foot of a wine glass, for instance, but I have found that with smoothing them, it makes them to look like either a pancake or a paperplate, here is a fine example of this cylinder that I used the subserf modifier on:    It's just a simple cylinder:   And when I subsurf it, it makes like these ridges in the middles of what would be the tris.

How can I use the subdivision surface modifier to create more high poly meshes without ruining sharp edges? For example this mesh  The sphere should be subdivided but the rim of the cylinder should stay the same because it is a sharp edge. This is the result of the subdevision  How can I get sharp edges to not be affected by the sub surf mod?


I am logged in to SE and can access the different sites, being logged in.  When I go to Ask Ubuntu, I am not indicated as logged in. When I press Google-log in, I am told that the activity is suspicious and I am denied log in.  How can I access Ask Ubuntu, being logged in with my account?  Earlier I have used Ask Ubuntu from my phone with no problem. I now fail to log in using Chrome on Windows 10.

I am getting this error repeatedly when I try to login to the  site for the first time using a Google id.  Sorry, your request could not be completed because it looked suspicious. If you meant to perform an action on Physics, please return to the previous page and try again.  I am using few other Stack Exchange and Stack Overflow sites,


If $A|B$ and $B|A$ then prove $A=\pm B$   So far I have $A|B \iff AX=B$ and $B|A \iff BY=A$ with $X,Y \in \mathbb{Z}$  Not sure how to finish, any help.

Prove or disprove: If a, b belong to the set of positive integers, and if a divides b and b divides a, then a=b. Does this hold if if a,b are not necessarily positive? Why or Why not?   Here is what I have:  If a and b are integers, we say a divides b if there exists an integer k so that b=ak. Thus:  $$b=ak$$  $$a=bj$$   $$a=akj$$ $$kj=1$$   Since a divides b and b divides a, we know that k,j must both be integer, which means k and j must both equal 1 or -1. This means:   $$a=b$$  This proves that a=b when we assume that a,b are both positive integers.   For the second part of the question, I am asked if I can still say a=b if the assumption about a, b is relaxed so that a,b belong to the integers (not the positive integers.) I think The answer is no, I cannot say that a=b for every case when we allow a,b to also be negative integers.   Here is my reasoning (I use the same idea that a=bj and b=ak here)   $$+/-a=akj$$  $$+/-1=kj$$   So $ |a|=|b|$ but not $a=b$  I'm very new to proofs so any suggestions or thoughts are greatly appreciated.


Is there a way to tell when a disk has been burned by inspecting the disc for its physical features?

Is there a way/tool to determine the date and time when a disc has been written/burned with high certainty? This is about data forensics and should be a solid proof. I already tried IsoBuster, but it didn't show me the date/time at which the track has been written.


I have Samsung Galaxy S2 GT-I9100. As it has 16GB internal memory but it only shows that it has 1.97GB of device memory. I am not talking about the memory that is free after using some of the space. This is the max memory that it is showing. I have tried resetting to factory settings and erasing everything. Also, I cleared cache and dump logs. Nothing have helped me yet. When I connect it to my laptop, it shows that phone has 8.56GB used out of 11.4GB. But that is USB storage, isn't it? Under settings > storage > device memory [Total space = 1.97 GB]. The problem arises when I install few of the applications and it starts showing that you are running out of storage. I don't understand what it is showing only that much space.

I have an HTC Wildfire (the original, not the S version). It is supposed to have 512MB of memory. When I check my free space in the app manager I noticed I have around 185MB. Why is this?  I am using CyanogenMod which is around 80MB, if this wasn't accounted for there is still a lot of space missing. Why is my phone reporting so little?


I'm trying to find out on what workstation the user is loged in at the time. I haven't found a way yet. Is this even possible? I have a username and want to get his current workstation.  I have domainadmin permissions and the client is in a domain. Using Powershell v5.

I am hoping that somewhere in Active Directory the "last logged on from [computer]" is written/stored, or there is a log I can parse out?  The purpose of wanting to know the last PC logged on from is for offering remote support over the network - our users move around pretty infrequently, but I'd like to know that whatever I'm consulting was updating that morning (when they logged in, presumably) at minimum.  I'm also considering login scripts that write the user and computer names to a known location I can reference, but some of our users don't like to logout for 15 days at a time.  If there is an elegant solution that uses login scripts, definitely mention it - but if it happens to work for merely unlocking the station, that would be even better!


everyone.  First of all, I am not sure if the question was praised properly but I tried as best as I could. Also, do note that I just started learning Python because I wanted to create a simple computer program I wanted to use. I wanted to ask question here because I encountered a problem that might seem easy to pros but I can't seem to figure out the solution.  Here is the code I wrote...  from tkinter import * from tkinter import ttk from PIL import Image, ImageTk  class Application(Frame):     def __init__(self, master):         ttk.Frame.__init__(self, master)          self.grid()         self.create_widgets()         self.FIDSIA_Amount()      def create_widgets(self):         self.label1 = Label(self, text='Type').grid(row=1, column=12, sticky=E)          self.Type = ttk.Combobox(self, width=7, textvariable=varSymbol, state="readonly")         self.Type['values'] = ('--------', 'A','B','C')         self.Type.grid(row=1, column=13)         self.Type.bind("<<ComboboxSelected>>", self.adjustmentFIDSIA_Planet1)      def adjustmentFIDSIA_Planet1(self, event):         content = self.Type.get()          if content == 'A':             varP1f = 0             varP1ind = 12             varP1d = 1             varP1s = 0             varP1inf = 0             varP1app = -15         elif content == 'B':             varP1f = 0             varP1ind = 12             varP1d = 1             varP1s = 0             varP1inf = 0             varP1app = -10         elif content == 'C':             varP1f = 0             varP1ind = 12             varP1d = 1             varP1s = 0             varP1inf = 0             varP1app = -5         elif content == '--------':             varP1f = 0             varP1ind = 0             varP1d = 0             varP1s = 0             varP1inf = 0             varP1app = 0      def FIDSIA_Amount(self):         amountf = Label(self, textvariable=varP1F)         amountf.grid(row=1, column=1)         amountind = Label(self, textvariable=varP1Ind)         amountind.grid(row=1, column=3)         amountd = Label(self, textvariable=varP1D)         amountd.grid(row=1, column=5)         amounts = Label(self, textvariable=varP1S)         amounts.grid(row=1, column=7)         amountinf = Label(self, textvariable=varP1Inf)         amountinf.grid(row=1, column=9)         amountapp = Label(self, textvariable=varP1App)         amountapp.grid(row=1, column=11)  root = Tk()  varP1f = IntVar(root) varP1ind = IntVar(root) varP1d = IntVar(root) varP1s = IntVar(root) varP1inf = IntVar(root) varP1app = IntVar(root)  varSymbol = StringVar(root, value='--------') varP1F = StringVar(root) varP1F.set(str(0+varP1f.get())) varP1Ind = StringVar(root) varP1Ind.set(str(0+varP1ind.get())) varP1D = StringVar(root) varP1D.set(str(0+varP1d.get())) varP1S = StringVar(root) varP1S.set(str(0+varP1s.get())) varP1Inf = StringVar(root) varP1Inf.set(str(0+varP1inf.get())) varP1App = StringVar(root) varP1App.set(str(0+varP1app.get()))  app = Application(root)  root.mainloop()   So, basically, I created a window with 6 numbers in it and next to it, there is a combobox dropdown menu listing 4 items (--------, A, B, C). What I want to do is when -------- is selected in combobox, I want 6 digits to be 0. However, if I select A in combobox, I want the 6 digits to be updated in the window by adding each of the 6 variables on 0. So, when I choose A, it will look like "0 12 1 0 0 -15" instead of "0 0 0 0 0 0". With current code, I can't seem to do it. PyCharm shows 6 variables: varP1f, etc... have error -> local variable value is not used.  How can I fix this problem?

How can I create or use a global variable in a function?  If I create a global variable in one function, how can I use that global variable in another function? Do I need to store the global variable in a local variable of the function which needs its access?


The pendulum equation states that the time period $T=2π\sqrt{l/g}$. This is based on the small angle approximation where we approximate  l  $$\frac{{\rm d}^2 θ}{{\rm d}t^2 }= -\frac{g}{l}\sin θ \approx  -\frac{g}{l} θ.$$ So my question is, since the magnitude of $\sinθ$ is smaller than $θ$, through the approximation will the angular acceleration be larger reality, so its speed is overestimated and the time period smaller than without the small-angle approximation?

Suppose you have a physical . It is true that as amplitude increases, the period increases. Can we demonstrate this fact without explicitly finding the period (which is pretty involved and pretty messy) in:    an intuitive fashion,  rigorously?


In Python, I am looking for a generic way (i.e. ) to build an array with all possible combinations between a given one dimensional array and N one dimensional arrays.  Here is a simplified example.  Input  main = ["a1","a2","a3"] secondary = [["b1","b2"],["c1","c2","c3"]]   Expected output  [   ["a1","b1","c1"],   ["a1","b1","c2"],   ["a1","b1","c3"],   ["a1","b2","c1"],   ["a1","b2","c2"],   ["a1","b2","c3"],   ["a2","b1","c1"],   ["a2","b1","c2"],   ["a2","b1","c3"],   ....   ["a3","b2","c3"] ]

How can I get the Cartesian product (every possible combination of values) from a group of lists?  Input:   somelists = [    [1, 2, 3],    ['a', 'b'],    [4, 5] ]   Desired output:  [(1, 'a', 4), (1, 'a', 5), (1, 'b', 4), (1, 'b', 5), (2, 'a', 4), (2, 'a', 5) ...]


On AIX 7 I have a process whose name appears between square brackets in the ps output:        PID    TTY  TIME CMD   7798784  pts/2  0:00 [myproc]   9044154  pts/2  0:00 ps    10485770  pts/2  0:00 bash    I found that overwriting argv[0][0] leads to such a result. Is there any other reasons which could lead to this result?

$ ps -Awwo pid,comm,args   PID COMMAND         COMMAND     1 init            /sbin/init     2 kthreadd        [kthreadd]     3 ksoftirqd/0     [ksoftirqd/0]     5 kworker/u:0     [kworker/u:0]     6 migration/0     [migration/0]     7 cpuset          [cpuset]     8 khelper         [khelper]     9 netns           [netns]    10 sync_supers     [sync_supers]    11 bdi-default     [bdi-default]    12 kintegrityd     [kintegrityd]    13 kblockd         [kblockd]    14 kacpid          [kacpid]    15 kacpi_notify    [kacpi_notify]    16 kacpi_hotplug   [kacpi_hotplug]    17 ata_sff         [ata_sff]    18 khubd           [khubd]   What do the brackets mean? Does args always return the full path to the process command (e.g. /bin/cat)?


Getting this error message:      Invalid Form      Our apologies, this form has been disabled due to suspicious content. If you believe you have received this message in error, please contact the original form author.   Any advice?

This appears:     Our apologies, this form has been disabled due to suspicious content. If you believe you have received this message in error, please contact the original form author.     How can I make my form code work?


I am currently a 3rd year undergraduate student at a large public university. I am a music performance major. I'm very interested in applying to graduate school for either performance or music technology, which I am receiving a minor in. My biggest concern is that at the end of my freshman year I received a misdemeanor possession of marijuana  charge. I paid the fine and have been done with it for a while. Unfortunately, I can feel it haunting me still and the closer and closer I get to graduation and applying to graduate school the more I feel it creeping up on me. In my state nothing is offered to "remove" it from your record such as some states have diversion class.   So my questions are:  Is this something I should be extremely concerned about?   Will a university or conservatory completely disregard my application because of this reason? Or will affect their decision on my acceptance?   I didn't lose my scholarship because of it (and actually I have received more money from the school of music after applying for other scholarships) but will I be ineligible in the future?   Anything helps.  Thanks.

I was charged with possession of marijuana earlier this year. In my state, it's not a crime, just a violation with a fine. Technically, it's not even a conviction because there's a diversion program that results in the charge being dropped after a year. The problem is that it won't be dismissed and expunged until after I apply for graduate school. So right now the charge is listed as pending.   Do applications for a PhD in math ask about petty charges like this? I know some ask about felonies and convictions, but that doesn't apply here. I know if I were applying for law school or medical school, my situation would be very different. How badly will this affect my application should this show up in a preliminary background check? Do math graduate programs even do background checks?


I want to put at the end of my bibliography a list of "suggested reading", that are NOT cited in the text but are present in the .bib file.  I use biber+bibtex with the numeric style. By using the \BibliographyCategory command I was able to create 2 categories and It works fine. The only thing I don't like is that the "suggested reading" are printed in the bibliography with the [number] on the left, and I don't want that, mainly because there's no citation of these in the document.  Here's a screenshot:    Is there any way I can remove the citation number only on the entries of a specific bibliography category?

When using biblatex, suppose I have set up two separate bibliographies, how can I assign them different styles, e.g. one numbered and the other author-year format or some such thing.  \documentclass{article}  \usepackage[defernumbers=true]{biblatex}  \DeclareBibliographyCategory{cited} \AtEveryCitekey{\addtocategory{cited}{\thefield{entrykey}}}  \usepackage{filecontents}  \begin{filecontents}{\jobname.bib} @misc{A01,   author = {Author, A.},   year = {2001},   title = {Alpha}, }  @misc{B02,   author = {Buthor, B.},   year = {2002},   title = {Bravo}, }  @misc{C03,   author = {Cuthor, C.},   year = {2003},   title = {Charlie}, } \end{filecontents}  \bibliography{\jobname}  \begin{document}  \nocite{*}  \cite{A01,B02}  \printbibliography[title={References},category=cited]  \printbibliography[title={Further Reading},notcategory=cited]  \end{document}


There are currently 95.3k items in the Close Vote queue, and 2 items in the Reopen Votes queue. The number of reviews needed to close a question from the CV queue is 5, which is ridiculously high. Here's :  In the past 90 days, 46,506 close flags have been processed; 45,707 were marked as "helpful" (resulted in at least one close vote) and 34,000 have resulted in questions being closed.  That's 73% accuracy from <3k users flagging; i.e. the people we believe to be least-able to recognise a close-worthly question are already getting 3/4 of them right... do we really need a further 5 >3k users to back them up?  Here's my actual : Let's find a number n, such that requiring only n reviews to end a review results in the same action being taken as requiring 5 reviews, y% of the time. If we require only 3 reviews instead of 5, and we end up with the same outcome 95/90% of the time as we would do using 5 reviewers, why aren't we doing that already? Yes, I just made those numbers up. Shog help me..  For those that are dubious as to whether this would open the floor for questions wrongly getting closed, let me calm you down with this;  Firstly, don't forget that we have the ability to "Vote not to Close" in the review queue. In the normal question view we don't have this. This is why the bar to close can be lower inside the queue than it is out of it, because people can vote for .  Secondly, my feature-request is not too different to how we already handle the Suggested Edits queue, and a wrong suggested edit is just as reversible as a incorrectly closed question. Hell, we even have a re-open queue; and it's empty. Let's use it.   If you're still struggling, then how about I knock you clean out by suggesting we add the ability to flag a question for reopening. This would force the question into the reopen queue, and handle the small percentage of questions that incorrectly get closed. It would also allieviate a proportion of the flags moderators have to deal with at the moment. If we're worried about the question-owner spamming the flagging option, only enable it for non-owners.

Today, the size of the close-votes queue is 55k questions and growing. Is that a problem?   Which action could be taken to clean it up? It seems to be growing faster than Stack Overflow members are capable to handle it.


I have a NPE Exception, while I have all declared objects: Main class: package com.company; import javax.swing.*; public class Main extends Plansza{ public static final JFrame frame = new JFrame(); public static void main(String[] args) {     frame.setLocationRelativeTo(null);     frame.add(areaPanel);     frame.setVisible(true);     frame.setBounds(0,0,800,600); } }  GUI class: package com.company; import javax.swing.*; import java.awt.*; public class Plansza { int[][] area = new int[8][8]; static public JPanel areaPanel; Figura figura = new Figura(); public Plansza(){     plansza(); } public static void plansza(){     areaPanel = new JPanel(new GridLayout(8,8));     areaPanel.add(new JButton("PLAY")); } }  console log: Exception in thread "main" java.lang.NullPointerException at java.desktop/java.awt.Container.addImpl(Container.java:1117) at java.desktop/java.awt.Container.add(Container.java:1029) at java.desktop/javax.swing.JFrame.addImpl(JFrame.java:553) at java.desktop/java.awt.Container.add(Container.java:436) at com.company.Main.main(Main.java:7)  the at com.company.Main.main(Main.java:7) is : frame.add(areaPanel); Idk, should I create object panel in Main? I wanted extend main class by Plansza class, for more clearly code. Where is mistake? I'll glad 4 your help, thanks :)

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


EDIT: Inquiry already answered. Thanks, guys!  I realize this is probably the dumbest question ever & I'm likely missing something, but I'm absolutely stumped as to what causes this error message:     Uncaught exception 'PDOException' with message 'SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''index'' at line 1' in G:\server\www\mysite\engine\database.class.main.php on line 66   And here's the code that causes it:  // Åpne et nytt PDO objekt.         try {             $pdo = new PDO('mysql:host='. $dbhost. ';dbname='.$db, $usr, $pass);             $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);         } catch (Exception $e) {             die("Oh noes! There's an error in the query!"); // Dummy error msg.         }                     // Forbered forespørselen.         $row = $pdo->prepare('SELECT * FROM ?');         $ret = array();          // Så utfør forespørselen.         if($row->execute(array($page))) {              $result = $row->fetch(PDO::FETCH_ASSOC);             // Om forespørselen ble fullført uten feil, parsér data.             while($data = $row->fetchAll(PDO::FETCH_ASSOC))             {                 $ret = array_merge($ret, array($data['page_key'] => $data['content']));             }                     }   I recognize that parts of it are redundant and repeated, the code is very much work in progress. But the SQL statement isn't exactly advanced, it's just supposed to get everything from the table (which is the variable $page -- which is defined in the function).  Obviously I'm missing something, since it seems that the $page variable (which is "index") is causing the error, but I can't identify why. Any takers? I'd really appreciate the help!

Why can't I pass the table name to a prepared PDO statement?  $stmt = $dbh->prepare('SELECT * FROM :table WHERE 1'); if ($stmt->execute(array(':table' => 'users'))) {     var_dump($stmt->fetchAll()); }   Is there another safe way to insert a table name into a SQL query? With safe, I mean that I don't want to do  $sql = "SELECT * FROM $table WHERE 1"


I have to proof, that a symmetric group $S_n$, with $n \geq 2$ with support $\{a_1, a_2, ... , a_p\}$ such that $σ(a_k)= a_k+1$ (when $k < p$) and $σ(a_p)=a_1$, is generated by transposition $(1,2)$ and the cycle $σ=(1,2,...,n)$.  I started by verifying that $σ(1)(1,2)σ(2) = (2,3)$.  Then by iteration I show that the next transposition $(3,4) = σ(1)(2,3) σ(2)...$ Iterating until transposition $(n,1)$.  After this how can I then proof that $S_n$ is generated by this transposition?   Thanks!

Show that $S_n$ is generated by the set $ \{ (12),(123\dots n) \} $.  I think I can see why this is true. My general plan is (1) to show that by applying various combinations of these two cycles you can get each transposition, and then (2) to show that each cycle is a product of transpositions.  I'm just having trouble on the first step. Any ideas?


Is doping the emitter more than the collector crucial?  Would current not flow at all if both regions were equally doped? Why? Is there a way to explain this in a simple fashion?

I was wondering, in a BJT why does the collector doping concentrarion have no effect in determining the current gain? I am trying to understand this conceptually but I can't seem to wrap my head around it.


I've been struggling with this question I've been assigned for a couple weeks now.  The question is to show from ZFC that there is an uncountable sequence $〈f_α:α→ω:α<ω_1〉$ of functions such that   Each $f:α→ω$ is injective, and for each $α<β<ω_1$, $\{ξ∈α:f_α(ξ)≠f_β(ξ)\}$ is finite.   I believe it will be a matter of constructing the sequence outright, but I can't seem to get the definition right so that it doesn't cause problems at limit ordinals, even if I avoid an infinite number of values in the range of $f_α$.  I may be thinking about this wrong, so any help would be appreciated.

Assuming the axiom of choice, show that there exists a sequence of function $\langle f_\alpha\mid\alpha<\omega_1\rangle$ such that: (1) each $f_\alpha:\alpha\rightarrow\omega$ is injective and (2) for all $\alpha<\beta$, the set $\{\gamma<\alpha\mid f_\alpha(\gamma)\not=f_\beta(\gamma)\}$ is finite.   My knee-jerk reaction in trying to solve this problem is to define the sequence by recursion. But I don't see how to actually carry out the construction (in particular, I don't see how I could ensure that (2) remains to be the case once I pass $\omega$). Any help is appreciated.


Prove that if $m\not =n,a$ are positive integers then $(a^{2^n}+1,a^{2^m}+1)$ is $1$ if $a$ is even and $2$ if $a$ is odd.    I solve the problem in the following way: I assume that $m>n$ then  $$a^{2^m}+1=a^{2^m}-1+2$$ With this expression if I take a divisor prime $p$ of $a^{2^n}+1$ then if $p|a^{2^m}+1$ this prime must divide 2 and the result follows.   But, how can I prove this statement without use of primes? This exercise appears before the concept of prime is introduced then I prefer do not use it.    Any idea?   Thanks!

So today in my final for number theory I had to prove that the Fermat numbers ($F_n=2^{2^n}+1$) are coprime.   I know that the standard proof uses the following: $F_n=F_1\cdots F_{n-1}+2$ and then the $\gcd$ divides $2$, and it cannot be two, and hence the numbers are coprime.  However, he asked us to use the hint: "Let $l$ be a prime dividing $F_n$. What can you say about the order of $2$ in $(\mathbb{Z}/l\mathbb{Z})^\times$?"   I have been thinking about it and I cannot figure out how to use his hint.  Any ideas?


Our local food distribution site gives what they call sweet potatoes. They are purple looking on the outside with white inside. When I boiled them they got kind of black or green streaks in them. Am I cooking them wrong and are they safe to eat this way?  I peel and cut into cubes and boil till fork tender.

I've noticed that some of the Hawaiian/Okinawan purple sweet potatoes I boil will have brown spots inside the flesh, while others do not. What causes these brown spots? Are these safe to eat? I've tried to be careful when selecting the ones I get from the store, insuring there is no visible mold, discoloration, abrasions, or soft spots, yet I keep getting potatoes like this.   Brown spotted potato on left, normal color potato on right in the image.


I saved the pacman -Qqe output from a previous arch install and now I'm using this list to install all the packages I had at once. However some of them are already installed and it wants to reinstall them which I fear will break things. Is there a pacman parameter to ignore the packages that are already installed? Or at least not to reinstall them but just update.

I have a package that's installed on my PC as an dependency to another package.  I would like to have the package explicitly installed, but without actually re-installing it, or downloading any files.  Is this possible?  update:  I do not have any packages cached in /var/cache/pacman/pkg, which is one of the reasons I want to change the package detail without a re-install.  Even If I had the packages cached, running pacman -S  would mean the whole install proccess is run, which I also want to avoid.


I have  I asked 9 months ago, and accepted an answer that same day that helped me at the time. Things changed a few months later, and now there is a better way to solve the problem.   Should I change my accepted answer to the better way, or leave it on the way that helped me solve the question at the time?  It feels like penalizing the first answer to remove the accepted status. I could use the advice of some more experienced Stackers.

I've accepted an answer in 2010. In 2011 new options came to hand, and a better answer was posted. Should I move the accepted answer to the new one?


It is very easy to convert any variable into a different kind in many languages, which gave me an idea for another converting function, which should act like str() from Python. So what I found out is that itoa() is a function that turns an int to a char * (string): #include <stdio.h> #include <stdlib.h>  int main() {     int num = 200;     printf("%s", itoa(num)); }  But as it turns out, itoa() doesn't actually exist in my version of C, which they claim is C99: make_str.c:6:18: error: implicit declaration of function 'itoa' is invalid in C99 [-Werror,-Wimplicit-function-declaration]     printf("%s", itoa(num));                  ^ make_str.c:6:18: error: format specifies type 'char *' but the argument has type 'int' [-Werror,-Wformat]     printf("%s", itoa(num));             ~~   ^~~~~~~~~             %d  So I went to make my function instead called make_str(), though I still don't have a plan about how to convert variables into strings: char *make_str(void *var) {      }  Q: What other functions can I use to change the variables into strings?  No, not floating-point values, only int.

itoa() is a really handy function to convert a number to a string. Linux does not seem to have itoa(), is there an equivalent function or do I have to use sprintf(str, "%d", num)?


I am curious why people use elliptic curve in cryptography. I know the main requirement is , but elliptic curve is not the only curve with such property. Some of curves seem to be even simpler.  As an example, we can consider a circle given by the equation:  $$ x^2 + y^2 = 1 (mod p) $$  where $ x, y $ in $ Z_{p} $, $ p $ is prime. And the rule for addition is:  $$ (x_1, y_1) + (x_2, y_2) = (x_1 x_2 - y_1 y_2, x_1 y_2 + x_2 y_1) $$  that can be also written as:  $$ P_1 = (x_1, y_1) $$ $$ P_2 = (x_2, y_2) $$ $$ P_{1+2} = P_1 + P_2 = (x_{1+2}, y_{1+2}) $$ $$ x_{1+2} = x_1 x_2 - y_1 y_2 $$ $$ y_{1+2} = x_1 y_2 + x_2 y_1 $$  I think the circle has some benefits towards elliptic curve:   Easier to understand and to interpret. Better performance, because we have fewer operations in the addition rule. Easier to research for "good" primes $ p $ in cryptography tasks, because the number of points on the circle can be calculated much easier than using .   As far as I know, the presence of DLP is an unprovable fact. So we can only prove that there is no DLP, and if we haven't found this prove we can think that there is DLP. I have made a research and haven't found that there is no DLP for the circle, that makes me think it is a good curve to use in cryptography.  On the other hand, it is obvious that circle looks simpler than elliptic curve, that makes me think people tried to use circle in cryptography but left this idea because of something. Does anybody have some thoughts about why people don't use circle? Or perhaps, is there some literature about it?

There seems to be sources like , this , and some  that discuss elliptic curves in general and how they're used.  But what I'd like to know is why these particular curves are so important in cryptography as opposed to, let's say, any other polynomial degree $\gt$ 2 which you can then mod over some group.  It seems like once a modulus is applied then other function types should be acceptable as well.  It seems even less intuitive when just looking at the bubble vs curve as here:    Since there are other curves (let's say anything from a sin wave to the $x^3 + x$ or even just some unusually shaped contour) that could do the job.  It seems like they would provide much more surface area to get a larger space in $\mathbb{Z}_p$ or really just more possible combinations of connecting lines from some arbitrary $P$ and $Q$ to get $R$ as opposed to something as restrictive (on the graph) as beginning from some bubble (which would seem to unnecessarily reduce the possible combinations) and then use a modulus to implement the discrete logarithm problem.  Sorry if this seems a little naive of a question, I'm trying to write an implementation right now and just to understand it fully even if that means asking something that is taken for granted.  Perhaps just walking through a simple example (most of the ones I've searched are anything but), just a few sentences, would be rather helpful, from "A wants to talk to B" all the way up to "now E can't listen in between A and B".  EDIT:  So it seems like this is the version of elliptic curves over a finite field:    Yes that looks pretty random.  But I'm still not really seeing why they are the only equations that have cryptographic significance.  It's difficult to imagine that if you simply took some other higher degree equation and applied modulus (to place within a group), then it seems like it would make sense that you'd get something that's also comparatively random.


Show that if $f:\mathbb{C}\to\mathbb{R}$ is continuous and $f\ll1$ ($a\ll b$ means $|a|\leq |b|$), then $\int_{|z|=1}f\ll4$.  Hint: Show first $\int f\ll\int_0^{2\pi} |\sin t|dt$.  I'm not sure how to prove the hint. In addition, what does the notation of $|z|=1$ below the $\int$ sign means?

Let $f$ be a continuous real-valued function in a circle $|z|\leq1$ and $|f|\leq1$. Prove that $| \oint_{|z|=1} f(z)dz |\leq4 $.   Any hint, please.


I have a problem. I have a Windows user [domain\user] on my instance that has access to some database. I want to change the default schema for that login. I can do this when I create some test login and user in the database but not for my Windows user:  ALTER USER [MFG\giorgi.nakeuri] WITH DEFAULT_SCHEMA=[TBBS]   ...results in:     Cannot alter the user 'MFG\giorgi.nakeuri', because it does not exist   or you do not have permission.   But when I am trying to add it:  CREATE USER [MFG\giorgi.nakeuri] FOR LOGIN [MFG\giorgi.nakeuri]   I get:     The login already has an account under a different user name.   When I observe login in properties it has a check on the database and both user and default schema are dbo. But I can not change any of those from that window. I am connected to instance with this windows user and login server role is all: public, securityadmin, serveradmin, setupadmin, sysadmin.

I have a login called user1. user1 can execute stored procedure [Test].[SP1]  EXEC [Test].[TestSortation] EXEC [TestSortation]   Both of the above commands work.  Now if I give the user1 the server role of sysadmin in addition to public. the later of the 2 statements above fails, and throws this error:     Could not find stored procedure 'TestSortation'.   I don't want to have to change every stored procedure in the database to have the schema name included with EXECute commands manually. Can someone explain to my why this is happening. Also, is there a way to get around this, automatically fix my stored procedures, have the schema default to [Test]?


I'm planning to buy a new SLR Camera . I'm confused between the Canon 600D and 700D. What are the primary differences?

We all buy a new digicam/DSLR every now and then.  So what web sites do you use to get more information about cameras and compare them? Where do you look for technical information, camera reviews, recommendations, comparison tables, and so on?  (There isn't one right answer for this, so this is a Community Wiki question.  Please put one website recommendation per answer - if you know more websites, just write one answer for each one.)


Compute the following limit:  $$\lim_{x\to 0} \frac{\cos(a+2x) - 2\cos(a+x) + \cos(a)}{x^2}\   .$$  How would I go about solving this problem? I can't use l'Hospital.

compute the following limit:  $$\lim \frac{\cos(a+2x) - 2cos(a+x) + \cos(a)}{x^2}\   \mbox{as}\ x\to0.$$  How would I go about solving this problem? I have attempted to use trig identities (addition of angles) to try to simplify the problem, but it only seemed to make it worse... but without used ´Hospital


So is the  in the planetary distances related to Johann Kepler's discovery in 1596 that the ratios of the orbits of the six planets known in his day were the same as the ratios between nested Platonic solids who called it the Mysterium Cosmographicum?

Background: I was recently reading a book on the planets to my son and I noticed a pattern in the distributions of the planets.  The planets' distances roughly follow an exponential distribution.  Below is a plot of scaled, log orbital distances $$ \tilde{d_n} = \frac{\log(d_n/d_1)}{\log(d_2/d_1)} $$ with the line $an+b$:   Where $d_1$ corresponds to Mercury and so on. Ceres is included, Pluto is excluded.  By linear regression, $a = 0.90, b = -1.06$.  For the statistically minded, the data has a Pearson's correlation of 0.996.  Note that this is a well known phenomenon, see  and references.  The code used to generate the plot may be provided on request.  Question: What is the mechanism that leads to this distribution?  Aside: Is there a good introductory text on solar system formation for the mathematically inclined?  Update: This is also known as Titius–Bode law.


An electrical shock may cause burns, or it may leave no visible mark on the skin. In either case, an electrical current or voltage passing through the body can cause internal damage, cardiac arrest or other injury. Under certain circumstances, even a small amount of electricity can be fatal.  With that being said, what do you think is responsible for electical shoks, high voltage or hight current, or both at the same time?

Related:        From what I've heard:   110 V (or 220 V; household voltage pretty much) is dangerous (i.e. can kill you) I think there's consensus on this, no need to try :) 60 V (old telephone lines) is supposedly dangerous (never tried, only heard it once... probably won't try)   From what I know first-hand:   9 V is not dangerous (I've put a 9-V battery on my tongue, nbd... actually it kinda hurt!) 1.5 V can indeed be quite shocking with enough current (fell for one of those "Do you want some gum?" tricks back in high school...), but they sometimes do not use 1.5 V with the low amperage levels, some use a DC motor to vibrate and complete the trick.   So I guess there's two parameters here, voltage and current... but are there rough numbers on how much of each (or in combination, which I guess would be power) would be considered hazardous?  No old telephone lines have always been 48vDC well at least since from 1950s, if your skin is wet you can feel it slightly, like on your forearm.  Now the ring voltage is 90-110vAC with a 2 on 4 sec off cycle (USA).  It will ring your bell but good, should you be touching the wires when someone calls. The ring voltage rides on top of the 48vDC, so its present on the same two conductors that the voice voltage(DC) is on. Luckily it's 4 seconds off will give you a chance to get off the conductors with a scream (of pain).


I have a log file, which holds a customerid, and an event type. I want to add a new column called sequence, which should be a increasing number, and should be unique per customer. The table is append-only, record-by-record, no transactions, and I'd like the sequence number to be computed by a default function on the column. What is the least CPU intensive way to accomplish this? I tried googling but there are just too many hits on 'auto-increment', 'sequence', and 'serial' for the simple cases.

I was reviewing the  for PostgreSQL and I saw that Pg is likely going to get "identity columns" sometime soon.  I found some mention in  but nothing much  is_identity         yes_or_no         Applies to a feature not available in PostgreSQL identity_generation character_data    Applies to a feature not available in PostgreSQL identity_start      character_data    Applies to a feature not available in PostgreSQL identity_increment  character_data    Applies to a feature not available in PostgreSQL identity_maximum    character_data    Applies to a feature not available in PostgreSQL identity_minimum    character_data    Applies to a feature not available in PostgreSQL identity_cycle      yes_or_no         Applies to a feature not available in PostgreSQL    doesn't say much either     An identity column differs from a primary key in that its values are managed by the server and usually cannot be modified. In many cases an identity column is used as a primary key; however, this is not always the case.   But, I don't see anything else on them. How do identity columns work? Do they provide any new functionality or is this just a standard method to create sequences? Any breakdown of the new feature and how it works?


since my stuff were outdated I decided this afternoon to update everything to a newer version but now my .tex source do not compile anymore. Specifically I started getting errors on every \includegraphics I have in the source file and moreover it looks like the compiler can't find the images anymore since for each one of them it says "File /Images/[name of the image] not found". The folder structure is this one:    Tex [Name of the PDF] .tex source files Images   Image 1 Image 2    A typical (they're are all like this one) part of code giving me errors looks like this  \begin{figure}[h]     \centering     \includegraphics[scale=0.4]{Images/Ampere}     \caption{Definizione di Ampère}     \label{fig:Ampere} \end{figure}   I already included graphicx to my document so that is not the problem here.  How can I fix this?

After updating MiKTeX graphics package on 10/5/19 to version 1.3b (packaged on 10/4/2019 8:11:27 PM), I am unable to compile LaTex files that contain \includegraphics{}.  My system: Windows 10  with MiKTeX 2.9.7200  A minimum working example:  \documentclass{article} \usepackage{graphics}  \begin{document}  \begin{figure}    \includegraphics{MC_Antenna_Gain} \end{figure}  \end{document}   The error report   This is pdfTeX, Version 3.14159265-2.6-1.40.20 (MiKTeX 2.9.7200) entering extended mode (C:/Users/nicrog/Dropbox/T_P_2/Scholar/Grants/Written/EWU_20/Test.tex LaTeX2e <2018-12-01> ("C:\Program Files (x86)\MiKTeX 2.9\tex/latex/base\article.cls" Document Class: article 2019/08/27 v1.4j Standard LaTeX document class ("C:\Program Files (x86)\MiKTeX 2.9\tex/latex/base\size10.clo")) ("C:\Program Files (x86)\MiKTeX 2.9\tex/latex/graphics\graphics.sty" ("C:\Program Files (x86)\MiKTeX 2.9\tex/latex/graphics\trig.sty") ("C:\Program Files (x86)\MiKTeX 2.9\tex/latex/graphics-cfg\graphics.cfg") ("C:\Program Files (x86)\MiKTeX 2.9\tex/latex/graphics-def\pdftex.def")) No file Test.aux. ("C:\Program Files (x86)\MiKTeX 2.9\tex/context/base/mkii\supp-pdf.mkii" [Loading MPS to PDF converter (version 2006.09.02).] ) ("C:\Program Files (x86)\MiKTeX 2.9\tex/latex/oberdiek\epstopdf-base.sty" ("C:\Program Files (x86)\MiKTeX 2.9\tex/generic/oberdiek\infwarerr.sty") ("C:\Program Files (x86)\MiKTeX 2.9\tex/latex/oberdiek\grfext.sty" ("C:\Program Files (x86)\MiKTeX 2.9\tex/generic/oberdiek\kvdefinekeys.sty" ("C:\Program Files (x86)\MiKTeX 2.9\tex/generic/oberdiek\ltxcmds.sty"))) ("C:\Program Files (x86)\MiKTeX 2.9\tex/latex/oberdiek\kvoptions.sty" ("C:\Program Files (x86)\MiKTeX 2.9\tex/latex/graphics\keyval.sty") ("C:\Program Files (x86)\MiKTeX 2.9\tex/generic/oberdiek\kvsetkeys.sty" ("C:\Program Files (x86)\MiKTeX 2.9\tex/generic/oberdiek\etexcmds.sty" ("C:\Program Files (x86)\MiKTeX 2.9\tex/generic/oberdiek\ifluatex.sty")))) ("C:\Program Files (x86)\MiKTeX 2.9\tex/generic/oberdiek\pdftexcmds.sty" ("C:\Program Files (x86)\MiKTeX 2.9\tex/generic/oberdiek\ifpdf.sty"))) ! Undefined control sequence. \Ginclude@graphics ...\Ginput@path \set@curr@file                                                    {#1}\edef \uq@curr@file {\... l.8    \includegraphics{MC_Antenna_Gain}  ?    I will report this potential bug to  as well.


I am learning how to use blender for motion graphics, and I wanted to create a sort of blur-to-fade effect, and now I am trying to blur one object (with nodes) but I fail in getting the right composition of the render layers.  I have a scene with two cubes, each on different layers, each layer as a separated render layer.  Using nodes, I use the two render layers as inputs, I blur one and leave the other as-is. Then I want to compose the output so that only the objects are composed (one object over the other), but apparently both images, including backgrounds, are mixed.  I tried to use , to my understanding it should work only on alphas of the image, but it seems to work on colors in some way.  I am using Cycles to render, and the world background has no alpha in the color, but I tried changing it and there is no difference in the output.  Here's a screenshot with the set-up.    Note in the bottom-left corner that the two cubes are overlapping: that is happening because I am using Fac = 0.8 in the Alpha Over node, but if I leave it to 1.0, I can see only the non-blurred cube and the other is hidden. If I use Fac = 0.0 I can see only the blurred.  I thought that Alpha Over would mix the images using only alpha channel, disregarding the red background, but obviously I am doing something wrong, because they are mixed with the background as well.  Where am I doing wrong? I hope it's clear what I want to achieve.  EDIT:  I tried following , and I basically want to get the same result.

I would like to render an animation as a series of .png images with transparent backgrounds for use in a video. Is this possible?


I am not sure if this is possible but I have a remote server running tmux and I frequently ssh into that server from a computer that is also running tmux.  The issue is that the tmux.conf filed are the same so when I try to run a command like detach with prefix-d I detach from my local tmux session when I actually want to detach from the remote one.  I do not see anyway around this other than having separate tmux.conf files but I thought I would check.

I have the following in my .tmux.conf  set -g prefix M-j bind-key j  send-prefix   I need to press (Atl+J) + (J) + bound-key to send something to the nested tmux session. I feel it is rather slow. Is there any better way? For example, I would love to be able to do (Alt+J) + (2x bound-key) to do stuff in the nested session. I constantly execute commands in the top tmux session instead of executing them in the nested one. Also, how come everybody binds prefix to C-a? I find it awfully slow and unpleasant to type this combination. Am I missing something?


How do you make less mistakes in math? Do you try to be more alert, do you take your time more, or what? Usually I don't make that many mistakes, but sometimes (like now) I do math as I imagine I would do it if I was ever drunk. I just did a couple of problems and I'm confusing addition with multiplication, $\lt$ with $\le$ , and other stuff like this. I make most of my mistakes when I think about how to approach/solve a more open-ended or abstract problem, not when I actually write it down on paper.

Ever since high school, I've had a serious problem with math classes. Be it discrete math, algebra, calculus or linear algebra, I seldom have trouble understanding the texts or lectures, but when it comes to executing calculations on homework and exams, I can never do it: I keep making mistakes. It's been a constant source of frustration, and right now, I'm on the verge of failing linear algebra and second year calculus (which I've been avoiding for as long as I could). I'm currently going through all the exercises and videos on , beginning with one-digit addition, working my way back up to integrals. I was making a lot of mistakes with multiple digit subtraction and multiplication, so initially, I was hopeful that maybe with enough practice in those two things, I'd be good to go again. But it turns out that my mistakes aren't confined to any one task, and the number of mistakes I make per exercise just accumulates as the tasks become more and more computationally involved:  Thinking that 7 + 5 = 13 Neglecting negative signs when transcribing Carrying in multiple-digit addition when a digit hasn't surpassed 10 Multiplying instead of adding Using the wrong exponent laws, log laws, limit laws etc. Mixing up trigonometric function properties Forgetting to reverse signs when expanding negated expressions of multiple terms  A typical page from my notebook:  I've tried everything: going for walks, ensuring that I have good sleep, writing out every step with almost hilarious verbosity, changing rooms, starting with fresh notebooks, reviewing everything I write, trying different notations, heck I even spent a month refining my handwriting and posture for good measure. I'm certain I spend about twice as much time as other people practicing too. I avoid taking other courses in the same semesters that I take math courses. As far as personality goes, in general, I'm not exactly OCD, but I'm not careless either. I probably have more patience than most people -- a bit too much, as my friends would tell me. I'm sure you can also tell from my adequate grammar, punctuation and spelling that I probably don't have any kind of learning disability that would prevent me from following symbolic rules. I've gotten near 100% in a first order logic course too. Yet when I do math, I always screw up. It's been this way for over a decade, maybe more. I don't know what I'm doing wrong anymore, and I'm losing hope. What could I do?