KVM05786Y: The Communication host ADMK05786HTREDIRECT_JA3A is SUCESS KVM05786Y: The Communication host KOPYUTRCEPORT_JA3A is SUCESS KVM05786Y: The Communication host ADMK05786HTSRM_JA3A is SUCESS KVM05786Y: The Communication host ADMK05786HTIAS_JA3A is SUCESS KVM05786Y: Communication host ADMK05786HTOTN_JA3A is SUCESS KVM05786Y: Communication host ADMK05786HTWPM is SUCESS KVM05786Y: The Communication host OCAIDEKD_JA3A is SUCESS KVM05786Y: The Communication host ADMK05786HTSC_JA3A is SUCESS Tried as below  name: "Get data" shell: cat /var/tmp/http_data.txt register: key_data  set_fact: service_name: "{{ service_name | default([]) + [item|regex_search( 'The Communication host\s+"(\S+)"\s+is SUCESS.*','\1' )] }}" with_items: "{{ key_data.stdout_lines }}"

My data: KVM05786Y: The Communication host "ADMK05786HTREDIRECT_JA3A" is SUCESS KVM05786Y: The Communication host "KOPYUTRCEPORT_JA3A" is SUCESS KVM05786Y: The Communication host "ADMK05786HTSRM_JA3A" is SUCESS KVM05786Y: The Communication host "ADMK05786HTIAS_JA3A" is SUCESS KVM05786Y: The Communication host "ADMK05786HTOTN_JA3A" is SUCESS KVM05786Y: The Communication host "ADMK05786HTWPM" is SUCESS KVM05786Y: The Communication host "OCAIDEKD_JA3A" is SUCESS KVM05786Y: The Communication host "ADMK05786HTSC_JA3A" is SUCESS  From the above data, I want to display only the names below. This means taking the text that is found after host and before is. Please give me a Linux command that can do this. ADMK05786HTREDIRECT_JA3A KOPYUTRCEPORT_JA3A ADMK05786HTSRM_JA3A ADMK05786HTIAS_JA3A ADMK05786HTOTN_JA3A ADMK05786HTWPM OCAIDEKD_JA3A ADMK05786HTSC_JA3A  I tried this in ansible: name: "Get data" shell: cat /var/tmp/http_data.txt register: key_data set_fact: service_name: "{{ service_name | default([]) + [item|regex_search( 'The Communication host\s+"(\S+)"\s+is SUCESS.*','\1' )] }}"  with_items: "{{ key_data.stdout_lines }}"


I am using PostgreSQL and I am trying to create a view of data:  forecast_datetime, file_date, thing_id, thing_name, facts...   The forecast_datetime column is a datetime for each 30 minute interval. The issue is that the forecast is for 1 month into the future which causes a lot of duplicate data. (so today, there will be a forecast for 2016-12-25 01:30:00 and then tomorrow there will be a forecast for the same interval, over and over again potentially until the period actually happens.).  The view I want to create is to just take a look at the last forecast which was appended to the table. This is indicated by the file_date column (as the name suggests, I receive a daily forecast file which is appended to the database. This column indicates the date from the filename).   I basically want to filter all rows for each thing_id and select the forecast_datetime columns where there file_date was the maximum date for that forecast. So each thing_id should only have one row per unique forecast_datetime interval which is based on the latest file_date.  CREATE OR REPLACE VIEW schema.view AS  SELECT DISTINCT ON (thing_id, forecast_datetime, file_date)        forecast_datetime,        interval,        time_zone,        file_date,        thing_id,         thing_name,        other_cols... FROM   schema.orig_table ORDER  BY  file_date DESC    Would that query do the trick? I can do this in pandas/python easily, but I am newer to SQL and wanted to try a view instead of writing a new physical table.  Here is some sample data after applying the query I wrote above this. Because I included the the file_date in the SELECT DISTINCT query, there is still a repeat row which duplicates each forecast_datetime. This causes issues when I join this data based on the thing_id and forecast_datetime back to the actual results table.  forecast_datetime   file_date   thing_id 2016-12-12 20:30    2016-12-11  99 2016-12-12 20:30    2016-12-10  99 2016-12-12 20:30    2016-12-09  99 2016-12-12 20:30    2016-12-08  99   I would like to only have the row with the max file_date. In the example above, that would be the first row (2016-12-11). The other rows would be dropped from the view.

I have a query pattern that must be very common, but I don't know how to write an efficient query for it.  I want to look up the rows of a table that correspond to "the most recent date not after" the rows of another table.  I have a table, inventory say, which represents the inventory I hold on a certain day.  date       | good | quantity ------------------------------ 2013-08-09 | egg  | 5 2013-08-09 | pear | 7 2013-08-02 | egg  | 1 2013-08-02 | pear | 2   and a table, "price" say, which holds the price of a good on a given day  date       | good | price -------------------------- 2013-08-07 | egg  | 120 2013-08-06 | pear | 200 2013-08-01 | egg  | 110 2013-07-30 | pear | 220   How can I efficiently get the "most recent" price for each row of the inventory table, i.e.  date       | pricing date | good | quantity | price ---------------------------------------------------- 2013-08-09 | 2013-08-07   | egg  | 5        | 120 2013-08-09 | 2013-08-06   | pear | 7        | 200 2013-08-02 | 2013-08-01   | egg  | 1        | 110 2013-08-02 | 2013-07-30   | pear | 2        | 220   I know one way of doing this:  select inventory.date, max(price.date) as pricing_date, good from inventory, price where inventory.date >= price.date and inventory.good = price.good group by inventory.date, good   and then join this query again to inventory. For large tables even doing the first query (without joining again to inventory) is very slow.  However, the same problem is quickly solved if I simply use my programming language to issue one max(price.date) ... where price.date <= date_of_interest ... order by price.date desc limit 1 query for each date_of_interest from the inventory table, so I know there is no computational impediment.  I would, however, prefer to solve the whole problem with a single SQL query, because it would allow me to do further SQL processing on the result of the query.  Is there a standard way to do this efficiently? It feels like it must come up often and that there should be a way to write a fast query for it.  I'm using Postgres, but an SQL-generic answer would be appreciated.


Let's say we know the standard deviation of a set of data. Furthermore, that set of data can be partitioned into subsets, and we know the standard deviation for each subset of that partition. What's the relationship between those standard deviations and the one for the whole set? Is it simple, like an average, or more complicated?

I'm running an experiment where I'm gathering (independent) samples in parallel, I compute the variance of each group of samples and now I want to combine then all to find the total variance of all the samples.   I'm having a hard time finding a derivation for this as I'm not sure of terminology. I think of it as a partition of one RV.   So I want to find $Var(X)$ from $Var(X_1)$, $Var(X_2)$, ..., and $Var(X_n)$, where $X$ = $[X_1, X_2, \dots, X_n]$.  EDIT: The partitions are not the same size/cardinality, but the sum of the partition sizes equal the number of samples in the overall sample set.  EDIT 2: There is a formula for a , but it only covers the case of a partition into two sets, not $n$ sets.


The type does not scale if I drag the side-handle of the text box, but when I adjust the width numerically it gets stretched. Is there a way to size a text box (I need it to match the width of other text columns) without scaling (distorting) the text.

Ok, I have a fresh Illustrator document. Pasted some copied text into the "artboard" (the clipboard is severely broken, but that's for another day).   The textbox that gets pasted is one huge line that goes from here to Timbuktoo.   So I need to resize it to 1/3rd of the page. I presume, as happens in every other sensible tool in the world, the text would flow to the width I give the textbox. The text itself will NOT get resized.   However, this is not what happens. THe text gets scaled completely. No exceptions.   I've been googling for the last 2 hours. Nothing works.    Some posts say I must "show bounding borders". Doesn't help at all. Other posts say some nonsense about main selection tool and direct selection tool. These tools do nothing. Both the arrow-icons, when used to drag the corners of the box, lead to the text getting resized anyway.  Someone suggested that when I copied and pasted text from a text file into Illustrator, this became an object, not actually text. Well, in that case, how should we paste text? Not everyone working on an Illustrator document is always and forever expected to write all the text manually, is it?    Seriously, how does this work? Any preferences I need to change? I used to work with CS4 and I recall it was much easier.   Would appreciate any inputs. Thanks!


I’m looking for a word I’m struggling to remember that refers to a job or role which is inconsequential and usually created in order to install someone in a company, not based on their merit.  An example would be creating a vague new role for a friend’s son. The word I’m looking for refers to the actual job itself - it’s a noun that would replace the ‘job’ (e.g “they put so and so’s cousin in a ____”).   I believe the word may not be a strictly formal or technical word but I don’t think it was slang.

What is the word used to describe a job given to a person just to give him/her the status of being in employment? The role does not effectively fulfil a purpose other than status and prestige. I read this word in an article months ago and have not been able to find it. I am referring to an adjective, not nepotism or tokenism, and the concept is more general.  Example sentence:     Jim has a |word| job, it was given to him just to give him status and prestige.


Prove that $x^2+y^2=z^4$ has infinitely many solutions with $(x,y,z)=1$   Since gcd of $(x,y,z)=1$ either $1$ of them is even and the other $2$ are odd or all $3$ are odd.  Since the square of an odd is the form $4k+1$, and the square of an even is $4n$. Then all three cannot be odd because the sum of two squares mod $4$ is $4k+1+4n+1=4(n+k)+2$.  Thus one of $x,y,z$ is even and it cannot be $z$, since then $z^2\equiv 0$ mod $4$ and $x^2+y^2\equiv 2$ mod $4$. So one of $x,y$ is even.  Not sure how to keep going from here.

Prove that $x^2 + y^2 = z^4$ has infinitely many solutions with $(x,y,z)=1$.   Do I use the terms $x= r^2 - s^2$, $y = 2rs$, and $z = r^2 + s^2$ to prove this problem?  Thanks for any help.


I've encountered this recently and I just can't wrap my head around it. My book states that   $$A \rightarrow B \equiv \neg A \lor B$$  It's my understanding that $A \rightarrow B$ means that if $A$ is true, then $B$ is true.   But, $\neg A \lor B$ would allow for us to have that $\neg A$ is true and $B$ is true, which seems to be pretty much that exact opposite of $A \rightarrow B$, so how can these be equivalent?

Provided we have this truth table where "$p\implies q$" means "if $p$ then $q$":  $$\begin{array}{|c|c|c|} \hline p&q&p\implies q\\ \hline T&T&T\\ T&F&F\\ F&T&T\\ F&F&T\\\hline \end{array}$$  My understanding is that "$p\implies q$" means "when there is $p$, there is q". The second row in the truth table where $p$ is true and $q$ is false would then contradict "$p\implies q$" because there is no $q$ when $p$ is present.  Why then, does the third row of the truth table not contradict "$p\implies q$"? If $q$ is true when $p$ is false, then $p$ is not a condition of $q$.  I have not taken any logic class so please explain it in layman's terms.       Administrative note. You may experience being directed here even though your question was actually about line 4 of the truth table instead. In that case, see the companion question  And even if your original worry was about line 3, it might be useful to skim the other question anyway; many of the answers to either question attempt to explain both lines.


I have tried several times to order a canvas print and it always comes back that the picture submitted will not work with the 11 x 15 canvas print and even an 8 X 10 wont work? I have a cannon E ( wont let me print name Santa's E )camera. What is the best type of camera I can buy that I can then make my pictures into Canvas photo's for my house? Just need the name of a good camera and know that it will turn into a wonderful Canvas photo.

I would like to create a 60 inch x 20 inch canvas print using an image with a resolution of 4759x1798 (240 pixels per inch) and I would like to know if the image quality will still be good at that size.  To generalise the question, what is the recommended maximum size of an enlargement at varying image resolutions?  e.g. 3 megapixel, 5 megapixel, 8 megapixel, etc


My site has been online for more than 2 months now , I also have set up the default meta data from W3Schools ,   But when I do searches on google for example, "data strategy", "the data strategy", "thedatastrategy" I don't see my site.   But if I do "site:thedatastrategy.com" my site pops up. Thus the domain name is well indexed in the google database.  What more am I supposed to add? Are there some more meta data information I have to add? Or am I supposed to register my site on some google service ?   I am not sure what to do now. When I tried searching this answer on google, I get the response that wait for some time and google would have crawled and indexed your site. But I have already waiting more than 2 months, and the results are like before.

What are the best ways to improve a site's position in the Google search results?


Is there a way, using ABE to let users get to subfolders they have access to, in folders they don't have access to?  Example  \[sharedrive]\shares\accounting\group1\bills\  shares is set to everyone can read  accounting is set to only group act can read/write  bills is set to only group contractors can read/write  I want contractors to be able to start in shares and go through the folders to get to bills without having to give list rights to contractors for the folders they need to go through. I know that would be easier but the actual share drive I am working with is huge with tons of different share permissions, there would be tons of folder permissions to change to get ABE to work.  EDIT:  WITHOUT having to give list rights on all other folders.  If it is not possible just let me know. I am asking because as I said before there would be a TON of permissions to change if I had to go through and change permissions on all the folders in the path.

I have a group of users on Windows Server 2003 who need to be able to read the contents of two directories but not be able to access anything else on the server (including read-only access).  One of the directories is K:\projectFour\config — and the other is similarly formatted — so it would be okay for group members to be able to list the contents of K:\ and K:\projectFour\ but not actually read anything in those directories.  I've found several resources via SF/Google, including how to restrict individual folders/drives and how to allow users to only run specific executables, but that information ultimately didn't solve my issue.  Sorry if this is a really simple thing to do, I'm usually a developer and don't know the first thing about servers or group policies.  Finally, I should mention that this isn't a fully concrete question, as it will be implemented eventually but I don't personally have a copy of Windows Server 2003 to test with right now.


I have been trying to use a Pandas Dataframe  in Python 3 to find a specific id matching a name from a CSV file. The API I am reading from gives me the name António, along with other names, the way I need it to with the accent in a column called "first". I have an array of names that won't necessarily have all of the accents I need to match. This program seems to work for every name I try except for the ones that have different values for accented characters.  import pandas as pd  nameArray=[Antonio,Matt,Mark,Raul] playersUrl = 'https://www.FakeSite.com/players' playerData = pd.read_csv(playersUrl, names=["PLAYERID", "FIRSTNAME"]  for first, playerid in zip(playerData["FIRSTNAME"],playerData["PLAYERID"]):     for i in len(nameArray):         testName = nameArray[i]             if first == testName:             return playerid

I have a Unicode string in Python, and I would like to remove all the accents (diacritics). I found on the web an elegant way to do this (in Java):  convert the Unicode string to its long normalized form (with a separate character for letters and diacritics) remove all the characters whose Unicode type is "diacritic".  Do I need to install a library such as pyICU or is this possible with just the Python standard library?  And what about python 3? Important note: I would like to avoid code with an explicit mapping from accented characters to their non-accented counterpart.


The recent June 25th, 2020 blog article  shows a graph of how much spam SpamRam blocked between March 2 and April 1, 2014. According to that graph, "spam blocked" rose from about 3k on March 27 to about 20k on March 28, then the numbers fell for the rest of the month (about 13k on March 29, etc.). The spike is quite noticeable on the graph:  How can this spike be explained? More specifically, is this more related to a sudden increase in the volume of spam being posted by spammers, or does it relate more to an increase in spam detection capabilities (for example, a new release of SpamRam)?

Something sort of magic happened a short time ago, sometimes a graph is worth a thousand flags:    That's right, around March 28, the spam protection layer blocked about 20,000 spam attempts, mostly in  the form of suggested edits, while users didn't see much of an increase in what they had to flag in order to thwart it.  The false-positive rate remained the same, less than one percent - including a surprising amount of suggested edits that attempted to 'hijack' another user's question or answer with a completely different question. Yes, people are odd.   We capture the text that we block in our log table, which as you can imagine is getting quite obese with bacon and turkey flavored spam - I was wondering if any of you would find any value in me making a public dump of what we block available every 30 days or so? If yes, in what format would it be the most useful?  This is basically what you'd get in CSV format (or XML, JSON, SQLite DB):  DateTime  WhyBlocked  BlockedText  SiteWhereItWasBlocked   The WhyBlocked field will include text contain an integer that indicates if it was a suggested edit, post denied, post hobbled, etc.   Note, I'm currently working on a tool that will allow anyone interested to meta-moderate actions that the spam system takes. You just look at lots of crap while clicking 'spam' or 'not spam' - It's something I plan to hang off the network sort of unofficial-like for a while to determine just how useful of an endeavor it turns out to be. Tracking our false positive rate currently involves me running a query once each week, and counting the number of things that probably shouldn't have been blocked, of which there are exceedingly few. As you can tell, when we get .. this sort of volume, that quickly becomes an insurmountable task. Anyway, I digress.  What use would the data have, you ask?   You could conceivably come up with a list of the most prolifically spammed links Each spam bot has very specific purposes, from what I can see. Some simply determine what kind of markup your site accepts by attempting to spam, then see what renders. Categorizing these could be fun.  Times of the day that we tend to get hit the most Some of it is solid comedic gold, just browsing the CSV can yield some lulz   Exporting this would be a bit of a manual process for me, so please only indicate interest if you have something beyond morbid curiosity as a motivation. No identifying information can (of course) be included, but there's plenty of interesting things you could do without it.   What say you, meta? I've released this previously - I'm wondering if it would be a useful regular thing.


I've written a short bash script to record the temperature of my Pi which I'll schedule in cron to run every 15 mins and output to a file on my desktop called readings.txt The problem is the command needs sudo privileges to run. So my question is how do I enable automatic entry of the password into the command within the script? #!/bin/bash sudo vcgencmd measure_temp >> ~/Desktop/readings.txt

To do a patch manually I must type this command   sudo ./playback_delete_data_patch.sh 09_delete_old_data_p.sql     There is a space just before the 09:   sudo ./playback_delete_data_patch.sh [space] 09_delete_old_data_p.sql   How can I run this inside a script?  There are also several other commands but this one is giving trouble.


I created one application (*.exe) it works fine in all systems but in one system it throws an error.     "class does not support automation or does support expected interface "

I have a COM dll written in vb6. When I try to create a new object of a class module from this dll I get a Run timer error 430: Class does not support automation or does not support expected interface. The interesting thing is that this happens only from outside the IDE, when I am debugging from within the IDE there is no error thrown and the new object of the class is created successfully. What can be the cause?  In general I occasionally get these kind of errors in COM dlls. What is the best way to debug COM issues? How can I know the path of the dll that is being used when a program is running?


I wonder what happens when you construct the Tiling spaces considering the natural action of $SE(n)$ or $E(n)$ rather than $\mathbb R^n$. In order to do that, I need to understand both the riemannian metric, and the volume form of the considered group. Are they unique?   Could you suggest an example based reference on Lie groups?

I am not an expert in this so I hope this doesn't sound so stupid: what is the common metric used when studying the Euclidean Group $\mathrm{E}(3)$. One could probably ask the same thing for (homogenous) transformation group $\mathrm{SE}(3)$. For the latter I have seen use of Riemannian metric. For both I am guessing (as this is not my field) that there are some kind of manifold structure involved, so I can't help to think that there are also good metrics (by good I mean metric that is considered "practical" when one considers rigid body motions).  Furthermore, is there a way to visualize the manifolds from $\mathrm{E}(3)$ and $\mathrm{SE}(3)$? Any good reference in this area?


I'm reading my textbook and it said if I'm downloading java jdk Id want to set my path variable. But I already download my java JDK and JRE and its completely functioning.(I'm using eclipse). However, I'm curious about the path variable and what it does specifically.

Questions about    setting environment variables the PATH   are very common here, and in most cases the answers are very similar to each other. In the future it would be nice to have a good Q/A for this.  So the question is: What are environment variables, like the executable PATH, and how can I change and use them on major operating systems?  A good answer would include a simple explanation of what environment variables and especially PATH mean to the OS, as well as simple guidelines on how to set and read them accordingly.


Show a metric space X is connected iff \forall non-empty proper subset A \subset X the boundary (set of points in X whose neighborhoods contain points from both A and the complement) is non-empty.

Is it true that if $X$ is connected, then for every nonempty proper subset $A$ of $X$, we have $\mathbf{Bd} \ne \emptyset$? Does the converse hold?  I start by trying to understand what $\mathbf{Bd}$ means in "formal terms" (i.e. $\bar{A} \cap \overline{X-A}$ is the 'boundary' of $A \in X$)?  This means I'm supposed to figure out if the boundary of subset of a connected space is empty or not, right? I think that if a set is connected then it contains no partition into two sets, so there would exist points that are both in $A$ and in the complement of $A$ in $X$. This would be an informal definition of a boundary. (A boundary contains points in a set $A$ and points outside of it, right?)   What I mean is, if $X$ is connected, and $A \subset X$ is connected, then $A$ could have a boundary which means that technically, $X$ cannot be partitioned into $A$ and $A$-complement without making the boundary of $A$ an empty set.  Right?


I am an Indian passport holder and recently applied for a tourist Schengen visa to French embassy (from Singapore). However, I am not able to provide complete documents for the application. I took my passport because I have to travel for work. If I am willing to withdraw my application, does withdrawing application during the visa process reduce chances of Schengen visa in future?

I recently applied for a business Schengen visa to Switzerland (from India). However my visa approval is delayed and the purpose of the trip, which was to attend some crucial meetings, is not applicable any more. My client and I do not feel it is necessary to make the trip anymore and would like to withdraw/cancel my visa application.   Is this easy to do? Will canceling my application reflect poorly on me and hamper my future chances of traveling to the EU region or to Switzerland?


Can I use youtube-dl for that?  I've downloaded youtube videos with the help of youtube-dl but one by one. I mean to say is there any command by which I can download all the vidoes in a particular playlist?

I'm trying to download some videos in mp3 format. It's a playlist. How do I download the whole playlist using one command?


If we define a function $\phi : D_{2n} \rightarrow D_n \times Z_2$ for odd $n$ and we want to show that it is an isomorphic function, I am not very sure how to do it.  We know that $D_{2n} = \{e, r, \ldots, r^{2n-1}, s, rs,\ldots, r^{2n-1}s\}$ and $D_n = \{e, t, \ldots, t^{n-1}, u, tu, \ldots, t^{n-1}u\}$.  I think that if we define $\phi(r) = (t, 1)$, then we can show that it is a homomorphism by showing that $\phi(r)\phi(r) = (t, 1)(t, 1) = (t^2, 0) = \phi(r^2)$, but I do not know if this is enough already or if I have to do it for all possibilities?!  And then the bijection. I know that it is injective if $\phi(a) = \phi(b) \iff a = b$, but how do I prove it in this particular example? And how do I show that every element of $D_n \times Z_2$ has an element in $D_{2n}$ to prove surjectivity?

Let $n \geq 1$ be an odd integer. Show that $D_{2n}\cong \mathbb{Z}_2 \times D_n$. I define a map $$\phi:D_{2n} \rightarrow \mathbb{Z}_2 \times D_n$$ by $R \mapsto (0,r^{\frac{n+1}{2}})$ and $M \mapsto(1,m)$. Then I am stuck at showing the map is bijective. By the way, do we need to show that $(0,r^{\frac{n+1}{2}})(1,m)(0,r^{\frac{n+1}{2}})^{-1}=(1,m)$ ? If we can prove this, then what can we conclude?


I am learning shell scripts here and would like to know how to automate user input (Y/ n) during package installation. I inserted echo Y for input "yes" on line 4 but it doesn't seem to work. The linux terminal still prompts me for input. Any suggestions? Thanks in advance..  echo "System update is starting..." sudo apt-get update sudo apt-get upgrade echo Y echo "installing keyboard..." sudo apt install matchbox-keyboard

Of course when you type:  sudo apt-get install whatever   It asks you:   Do you want to continue [Y/n]?    Is there any way I can just install it without it asking me if I want to continue? I don't really care about space, I have more then enough.


I'm creating a method that is supposed to find the path to a text file and return it as a String to be used for a configuration file. Here's the block of code that is being affected:  public String getConfigLocation() {         String fileName = "locateconfig.txt";         ClassLoader classLoader = ClassLoader.getSystemClassLoader();         File file = new File(classLoader.getResource(fileName).getFile());         locationFile = file.getAbsolutePath();         return locationFile;     }   The line that's causing this exception to be thrown is File file = new File(classLoader.getResource(fileName).getFile());.  Here's the first few lines of the stack trace - just the first few, because all the methods being affected here interact with the one I'm having a problem with.  Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException     at epicorexpert.EpicoreJFrame.getConfigLocation(EpicoreJFrame.java:1068)     at epicorexpert.EpicoreJFrame.checkConfig(EpicoreJFrame.java:1076)     at epicorexpert.EpicoreJFrame.<init>(EpicoreJFrame.java:94)   What probably-obvious issue am I overlooking? Thanks.  Edit: Why is this being marked as a duplicate question and suggesting a redirect for the thread on what NullPointerExceptions are? I understand what they are and how they're typically resolved. That's not what I'm asking here; this is specifically about the ClassLoader and File objects and why I'm getting NPEs from them.

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?


Prove that $$\lim_{x\to\infty}\left(1+\frac{a}{x}\right)^x = e^a$$ for $a$ not equal to $0$.

$$\lim_{x \to \infty} \left(1 +  \frac{a}{x}\right)^{x} = e^{a}$$     $1$. Without L´Hopital´s rule  $2$. With L´Hopital´s rule


If the photon (as a quantum of the electromagnetic field) has no defined(?) amplitude, how does (or where from?) the electromagnetic wave's amplitude appear?  The formulation of the question is not quite precise, but the main idea is if we cannot define the single photon's amplitude, since $E=hf$ only (are there any other equations?), how can we talk about an amplitude of an EM wave, which is carried via photons (EM quanta)?

At the end of this nice video (), she says that  is a chain reaction of electric and magnetic fields creating each other so the chain of wave moves forward.  I wonder where the  is in this explanation. What is the relation between electromagnetic wave and photon?


I have an unfortunate Java library that I've inherited that parses JSON.  Right now, if you ask for a key that doesn't exist in a JSON array, it dies with a null pointer.  I'm going to edit the library to do something more reasonable.  I think I have two options:  1) Return null so the caller can check  2) Throw a more explicit exception (more descriptive than "Null Pointer"), forcing the caller to handle the case where they asked for a non-existent key.  I come from a python background and am strongly drawn to number 2, seeing as it will ensure that some bonehead can't call this function and then continue on with a null value, crashing their application later on and possibly corrupting data.  Which way do YOU think is more in line with best practices of Java?  This is not a duplicate of other language-independent questions on the same topic.  This is specifically in the context of Java!!!!

I am using java language,I have a method that is supposed to return an object if it is found. If it is not found, should I:  return null throw an exception other  Which is the best practise or idiom?


Let $V$ be a finite dimensional vector space over $R$, then is it   possible to write $V$ as union of finitely many proper subspaces?   I am not sure but suppose if we have $B$ as an ordered basis for our vector space $V$, then we may break $B$ into $B_1$ and $B_2$ such that $B1\cap B2=\phi$ and $B1\cup B2=B$  So, isn't it true that $V=L(B1) \cup L(B2)$?  Where $L(B1)$ is linear span of $B1$

If $U_1$, $U_2,\ldots,U_n$ are proper subspaces of a vector space $V$ over a field $F$, and $|F|\gt n-1$, why is $V$ not equal to the union of the subspaces $U_1$, $U_2,\ldots,U_n$?


I have a problem here, that when I click the copy button on the recently copied row. It doesnt work. You guys know how to fix this?  This is my code  var controller = function(num1) {     $('#copy-' + num1).click(function() {        var $tableBody = $('#table_name').find("tbody"),         $trLast = $tableBody.find("#tr-" + num1),         $trNew = $trLast.clone();       // $trNew.find('input').val('');       $trLast.after($trNew);       console.clear()       // refresh_index();      });   }    function refresh_index() {     $('#table_name > tbody > tr').each(function(i) {        i++;       var select = $(this).find('select');       var text = $(this).find('input');       var button = $(this).find('button');        controller(i);      });   }   refresh_index();   This is my code in

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I saw this game at a friend's place but nobody knew what it was called. Google search and reverse image search didn't help.    This is a hexagonal board with:   10 white marbles 10 dark marbles 37 notches to put them in

Can anyone tell me what this game is called and how it is played? It's a small square board with 37 holes, 10 black pegs and 10 white pegs in opposite diagonal corners.


I login Stack Overflow with a Google Account, but I can not find a button or link to let me log out. The only way I got so far is clear my browser's cookie...  Do any guys know about it? Thanks.

Today I open my SO account like I always do. But the UI of menus has changed. I am not able to see the chat tab, the logout link or the privileges link. Are they missing or moved somewhere else?  Changed UI:


In PHP, a string enclosed in "double quotes" will be parsed for variables to replace whereas a string enclosed in 'single quotes' will not. In Python, does this also apply?

According to the documentation, they're pretty much interchangeable.  Is there a stylistic reason to use one over the other?


The following code:  class Parent {     public void method(List parameter){     } }  class Child extends Parent {      public void method(List<String> parameter) {     } }   fails to compile with the following error:   Parent.java:12: error: name clash: method(List<String>) in Child and method(List) in Parent have the same erasure, yet neither overrides the other     public void method(List<String> parameter) {                 ^ 1 error   But I'm checking that JLS8 in §8.4.8.1 says:     An instance method mC declared in or inherited by class C, overrides   from C another method mA declared in class A, iff all of the following   are true:       ...      The signature of mC is a subsignature (§8.4.2) of the   signature of mA.      ...   And in §8.4.2 it says:     The signature of a method m1 is a subsignature of the signature of a method m2 if either:      ...      the signature of m1 is the same as the erasure (§4.6) of the signature of m2.   And in this case both the original and the overriding method declarations have the same erasure, so why the compilation fails?

What is the concept of erasure in generics in Java?


There were 10 people who went to the store, vs. There were 10 people that went to the store.  Can we not consider reversing the subject and verb to ask a question and thus aid us in clarifying the answer? Wouldn't we ask "Who went to the store?" and not "That went to the store?"

I often get confused when trying to use who vs that.  Some examples that often confuse me:  That     The person that went to the store.      The people that went shopping.      The persons that went shopping.      The group that went shopping.   Who     The person who went to the store.      The people who go shopping.   Please explain when to use either for plural subjects and singular subjects.  Animate and inanimate objects as well.


I'm struggling to model my objects into a 90's retro vector style, with the wireframe and low poly look.    Freestyle won't render in a game mode, and it seems to use a tremendous amount of time just to render simple black outlines around my mesh faces.  It seems if I create two materials, one as "wire" and the other as a surface - it does the trick, however it's only 1 pixel thick, and seems to get lost.  When I pan around different angles, the matte material seems to take over the wireframe material.  Does anyone know how to modify the thickness of that wire attribute in the materials?    I don't want to create a whole different mesh object for the wireframe effect, that the blender previewer seems to handle gracefully by default in preview mode. The render animation seems to do a whole lot of extra work to render frames, and all I want is a retro 90's cartoon, and possibly do something in simulator / game mode.

Why does the wire-frame material fades across the object?  Here is what I did - I created a new material and I selected on "Wire" and I made it shadeless. Then, I created a new material and assigned the new material on the on the object. However, doing it that way, it allows me to render both materials - "Wire" and "Surface". Then I get a fading result like this -    But I want all of the edges to be shown, not a fading result. How can I make that?  Here is the blend file if anybody wants to check it out -


Which ones we should use:   the global population global population

In my Grammar book I have...     She's been watching television.    Can we also say...     She's been watching the television    I just want to know if they are the same.


RAM: 2143MiB / 3798MiB  What does this means ? I cannot even know about my laptop's RAM

Possible Duplicate:          I have Ubuntu 12.4 LTS and I need a program that will be able to monitor my ram usage. Any suggestions?


While thinking intuitively, it seems quite obvious that the object displaces itself in the downward direction. But, will there be a case where the buoyant force dominates over it's own weight which may cause the ball to rise?  (No information about the densities/masses of any object is given)

I noticed that when I had a helium filled, latex balloon inside of my car, it moved forward in the cabin as I accelerated forward. The faster I accelerated forward, the faster the balloon went from the back of the car to the front of the car. The balloon didn't have a string.  This became a game with my 4 year old as we drove home. We figured out where the balloon would go based on how fast I accelerated, turned corners etc.  I expected that it would act a lot like the water in a cup does, but it was the total opposite it seemed.  What forces caused this behavior?  I assumed it has something to do with the fluid dynamics in the closed cabin, but I can't figure it out.


Has anyone tried any quantum computing programming code that shows or demonstrates the advantage of a quantum computer over classical computers? Thanks a lot.

It is generally believed and claimed that quantum computers can outperform classical devices in at least some tasks.  One of the most commonly cited examples of a problem in which quantum computers would outperform classical devices is $\text{Factoring}$, but then again, it is also not known whether $\text{Factoring}$ is also efficiently solvable with a classical computer (that is, whether $\text{Factoring}\in \text{P}$).  For other commonly cited problems in which quantum computers are known to provide an advantage, such as database search, the speedup is only polynomial.  Are there known instances of problems in which it can be shown (either proved or proved under strong computational complexity assumptions) that quantum computers would provide an exponential advantage?


I want to block websites on my HTC phone.  It seems as though ES File Explorer needs the phone to be rooted to use this method, which I don't want to do. (I don't have any folders when I click through 'Local'-'Device' at all, which is where you're supposed to find 'etc' so I can't go any further anyway) Trend Mirco is far too expensive for the premium version which lets you block any site name (given I'm trying to block sites where I can spend money!) Firefox Add Ons don't seem to work on the mobile version, they will download, but I have no way of opening them. Apps all seem to be about blocking adult content on kid's phones, which isn't the issue here.  On the desktop computer I've used Leechblock for Firefox, and BlockSite for Chrome.  Any other ideas that don't cost anything or require a rooted device?

I am searching for a way to block websites without having root access. Is there any way to do it? Any help will be appreciated.


I recently bought a new telephoto lens for my Nikon D5000. With the new lens I started taking pictures of the moon.   When I take the pictures I have blue, red, and other colored dots in the photo, seen here:   I do not believe that they are stars.   Does anyone know if they are stars, or something I need to adjust with my camera's settings?

This is the Milky Way above Kakadu National Park, Australia, and my first try at astrophotography.    Thirty second exposure, f/4.0 at 17mm with ISO 12800 (!!) which in hindsight probably was way too high and resulted in a lot of noise. I also used Picasa to increase contrast, but I probably went a bit overboard there as well.  , I am looking for input on how to better postprocess this picture to reduce noise.


I am currently trying to understand the Fermi's golden rule.   We consider a system with Hamiltonian: $$\hat H = \hat H_0 + \hat Ue^{i \omega t},$$ where the expectation value of $\hat U$ i much smaller than that of $\hat H_0$.  At $t=0$ the systems is in the ground state $\lvert 0 \rangle$ of $\hat H_0$ (we assume that $\hat H_0$ has discrete spectrum). Using first-order, time dependent perturbation theory, we obtain probability of the system being in the state $\lvert n \rangle$ after time $t$: $$\lvert c_n(t) \rvert^2 = \frac{1}{\hbar^2} \lvert \langle n \rvert \hat U \lvert 0 \rangle \rvert^2 \frac{\sin^2 \left(\frac{(\omega_n - \omega_0 - \omega) t}{2} \right)}{(\frac{\omega_n - \omega_0 - \omega}{2})^2}.$$ As far as I understand, this is the probability (not probability density) that we find the system in a state $\lvert n \rangle$ after time $t$ (if we for example turn off the time dependent potential and measure energy of the system). Now, according to my notes, if we take the limit as $t \to \infty$, this probability tends to: $$\lvert c_n(t) \rvert^2 = \frac{2\pi t}{\hbar^2} \lvert \langle n \rvert \hat U \lvert 0 \rangle \rvert^2 \delta(\omega_n - \omega_0 - \omega).$$ This expression is infinite (undefined?) when $\omega_n - \omega_0 - \omega = 0$. However, even after a very long time the transition probability should be finite (and while we're at it, than one).  I would normally expect to see dirac delta when dealing with probability densities , however as I mentioned before we are considering transitions between discrete states, so Kronecker delta is what I would expect to see here.  My question is, what am I missing here?

I am slightly confused about the application of . Which during standard derivations indicates a probability of transitioning from the state $|i \rangle$ to the state $|f\rangle$ of: $$P=\frac{2\pi t}{\hbar^2} | \langle f | \hat V | i \rangle|^2 \delta(E_f-E_i-\hbar \omega)$$ This holds for large values of $t$ but for arbitrarily large values of $t$: $$P>1$$ Which (to me anyway) makes no physical sense since there can't be a probability greater then 1 of been in the final state. If my interpretation is right then how is this problem resolved/allowable? and if it is wrong what part of what I have said is wrong?


Using KOMA report, figures seem to default to numbering from 0.1, 0.2, 0.3... I'd like these to start from 1,2,3 instead.  I'm using    \documentclass{scrreprt}   Related, but don't answer my question:        Edit: This question: , was identified as a solution to my duplicate.  While that does look like a good answer, I've already successfully implemented the answer below.  It is different and does not require using another package.  As such, I prefer it.

I want the figures and tables to be numbered 1, 2, 3, ... until the end of the document instead of 1.1, 1.2, ... in chapter I, 2.1, 2.2, ... in chapter II and so on.  I know how to convert the "chapter" part of figure/table numbers from Roman to arabic:  \renewcommand \thefigure     {\ifnum \c@chapter>\z@ \@arabic\c@chapter.\fi \@arabic\c@figure} \renewcommand \thetable     {\ifnum \c@chapter>\z@ \@arabic\c@chapter.\fi \@arabic\c@table}   One could modify the above code in order to remove the "chapter" part, but the figure/table counters would still be reset to 0 at the start of new chapters.


I wanted to buy a bike and started checking for one online. I went through some nice ones on Aliexpress.com but the price is very suspicious to me. It's not just the price but also the free shipping via those expensive shipping companies.  Can someone (especially someone who understands Chinese) tell me if those are real bikes?   Check  link as an example.

I've notice that the business to business site AliBaba and it's more consumer friendly AliExpress website have a number of bike components for sale. They tend to be complete component groupsets and the like but are some quite reasonable deals, especially if you are building a bike from scratch.  I've used AliExpress before to purchase electronic components, which have been good quality and are what they say on the tin.   Has anyone used AliExpress to buy bike components and have they had any trouble? (quality, counterfeit etc.)  One benefit is that your money is held in escrow until you receive the item and aprove the payment so some safety.


I have two arrays by array_merge() that look like this:   Array(             [1] => Array(                   [date] => 2018-09-25                   [size_one] => 'XL'                   [name_one] => 'Shoes'                 )             [2] => Array(                     [date] => 2018-09-25                     [size_two] => 'L'                     [name_two] => 'Shirt'                 )             [3] => Array(                     [date] => 2018-09-26                     [size_two] => 'L'                     [name_two] => 'Shirt'                 )             )   If same date value, I need as a result something like the following:  Array(                 [1] => Array(                       [date] => 2018-09-25                       [size_one] => 'XL'                       [name_one] => 'Shoes'                       [size_two] => 'L'                       [name_two] => 'Shirt'                     )                 [2] => Array(                         [date] => 2018-09-26                         [size_two] => 'L'                         [name_two] => 'Shirt'                     )                 )   want to be able to put these into an array for laravel,  Can someone show me the proper way to merge these arrays?

We have two PHP5 objects and would like to merge the content of one into the second. There are no notion of subclasses between them so the solutions described in the following topic cannot apply.    //We have this: $objectA->a; $objectA->b; $objectB->c; $objectB->d;  //We want the easiest way to get: $objectC->a; $objectC->b; $objectC->c; $objectC->d;   Remarks:   These are objects, not classes. The objects contain quite a lot of fields so a foreach would be quite slow. So far we consider transforming objects A and B into arrays then merging them using array_merge() before re-transforming into an object but we can't say we are proud if this.


I want to know how i can make my model just a blank model with no vertices so that it will be easier for me to create other parts. i already checked this tread and it didnt help: Here is a pic of what it looks like right now:

I am wondering if there is a modifier or tool that will essentially undo a subsurf or subdivide command.


I am creating these div's dynamically when user adds products to compare.  //code in jquery var innerdiv='
'+value.name+'
'; $('#compare-pane').append(innerdiv);   How do I check dynamically if the compare pane is empty or it has inner divs?  I have to hide a button if compare-pane is empty.  The inner div id is dynamically generated  (e.g innerdiv166104).  How do I check if any inner div exists? I cannot use empty check as there are another elements inside compare-pane too which are required.  I cannot fetch the inner div id's as they will be coming dynamically as per users selection.

How can I check the existence of an element in jQuery?  The current code that I have is this:  if ($(selector).length > 0) {     // Do something }   Is there a more elegant way to approach this? Perhaps a plugin or a function?


If  $${\rm Cov}[dW_t,dB_t]=\rho \, dt$$  then why  $\mathbb{Cov} \left( \int_0^t \sigma_{1}(s) \mathrm{d} W_s, \int_0^t \sigma_{2}(u) \mathrm{d} B_u \right)$     $\stackrel{\text{Ito isometry}}{=} \rho \int_0^t \sigma_1(s) \sigma_2(s) \, \mathrm{ds}$  where $\sigma_{1s}$ and $\sigma_{2s}$ are two deterministic functions of $t$?  I do not understand why the $\rho$ emerges. I mean from the application of the Ito isometry the answear should not only be $\int_0^t \sigma_1(s) \sigma_2(s) \, \mathrm{d}s$?

I do not understand the following result:  Suppose $dz_\chi$ and  $ dz_\xi$ are correlated increments of standard Brownian motion with $dz_\chi dz_\xi=\rho dt$ you have the following expectation giving the following result:  $\mathbb{E} [\int_{t}^{T}e^{\kappa s} dz_\chi \int_{t}^{T}dz_\xi] = \rho \int_{t}^{T}e^{\kappa s} ds$  I really do not get it. This equation is justified by the Itô's isometry. In the book that I am reading the author just passes by saying that is easy to see, but if someone could show more explicit the steps that are taking to get this equation.


I installed MySQL server and I want to allow SSL support.  I added these lines to my.cnf  [client] ssl-ca=/etc/mysql/ca-cert.pem ssl-cert=/etc/mysql/client-cert.pem ssl-key=/etc/mysql/client-key.pem  [mysqld] ssl-ca=/etc/mysql/ca-cert.pem ssl-cert=/etc/mysql/server-cert.pem ssl-key=/etc/mysql/server-key.pem ssl-cipher=DHE-RSA-AES256-SHA   I created certificates  openssl genrsa -out ca-key.pem 2048; openssl req -new -x509 -nodes -days 1000 -key ca-key.pem -out ca-cert.pem; openssl req -newkey rsa:2048 -days 1000 -nodes -keyout server-key.pem -out server-req.pem; openssl x509 -req -in server-req.pem -days 1000 -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 -out server-cert.pem; openssl req -newkey rsa:2048 -days 1000 -nodes -keyout client-key.pem -out client-req.pem; openssl x509 -req -in client-req.pem -days 1000 -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 -out client-cert.pem;   I changed chown to mysql for *.pem certicates  -rw-r--r-- 1 mysql mysql 1407 Mar 10 13:00 ca-cert.pem -rw-r--r-- 1 mysql mysql 1675 Mar 10 12:50 ca-key.pem -rw-r--r-- 1 mysql mysql 1277 Mar 10 14:29 client-cert.pem -rw-r--r-- 1 mysql mysql 1704 Mar 10 14:29 client-key.pem -rw-r--r-- 1 mysql mysql 1045 Mar 10 14:29 client-req.pem -rw-r--r-- 1 mysql mysql 1277 Mar 10 14:28 server-cert.pem -rw-r--r-- 1 mysql mysql 1708 Mar 10 14:28 server-key.pem -rw-r--r-- 1 mysql mysql 1045 Mar 10 14:28 server-req.pem   then I restarted MySQL server and I logged to service like root and checked the status. But it is still showing that ssl is not in use. What I did wrong?

I'm running Ubuntu Server 12.04, and I want to enable SSL connections to MySQL.  I've generated the following keys/certs files with OpenSSL:   ca-cert.pem server-cert.pem server-key.pem   I stored these at /etc/mysql, then added added the following lines to /etc/mysql/my.cnf:  ssl-ca=/etc/mysql/ca-cert.pem ssl-cert=/etc/mysql/server-cert.pem ssl-key=/etc/mysql/server-key.pem   Next, I restarted the server with sudo service restart mysql.  However, this doesn't seem to enable SSL. Within a mysql session:  mysql> show variables like '%ssl%'; +---------------+----------------------------+ | Variable_name | Value                      | +---------------+----------------------------+ | have_openssl  | DISABLED                   | | have_ssl      | DISABLED                   | | ssl_ca        | /etc/mysql/ca-cert.pem     | | ssl_capath    |                            | | ssl_cert      | /etc/mysql/server-cert.pem | | ssl_cipher    |                            | | ssl_key       | /etc/mysql/server-key.pem  | +---------------+----------------------------+   Any ideas what I'm missing? Thanks


How does evolution rule out the possibility of humans or others fragile herbivores from having 2 pairs of eyes, one at the front and the other at the back of their heads? Why didn’t that ever happen?

If a trait would be advantageous to an organism then why hasn't it evolved yet?  Conversely, if a trait is not advantageous or mildly disadvantageous, why does it exist?  In other words why does evolution not make the organism more "perfect"?    This is a general question that would be applicable for any kind of trait. Please keep the answers precise and scientific.   Read this meta post for more information:


I saw a dozen or more clusters of what I think are insect eggs attached to a few vertical sticks protruding from a small pond, and a few more to stalks of grass nearby. Location is in Hsinchu County, Taiwan, end of March, fairly good weather these days in the neighborhood of 15-22 C.  Each cluster consist of a group of roughly 150 spherical hot pink colored eggs stuck to a surface, each about 2.5 to 3 mm in diameter. One group was deposited almost completely around a stalk of grass on land next to the pond, and several others were deposited on the side of a stick from a fallen branch sticking out of the water.  Questions:   Is it possible to identify what kind of insect produces such clusters of eggs? Is there any explanation possible for the "hot pink" color? I suppose it could be a general "don't eat me" signal like  but it's such an artificial looking color, I've never seen it anywhere in nature, at least that I can remember.     click images below for full size:       update:  suggests that snails are the likely culprits, and so I returned to the scene of the crime today and caught them red-handed, or in this case "pink-footed".  Click for full size; the larger snail is about 5 centimeters in diameter.      caught red-handed, or in this case "pink-footed"

Photo taken in a garden in Singapore. The organism is attached to a stone, close to water. Many of these were there.  Size approx 3cm.   The shell of this eggs is very soft. When touched, a pink colored liquid drops out.


Is there a way to change the background-image style with javascript? i currently have:   if($(".stLarge").attr.backgroundImage = "http://w.sharethis.com/images/facebook_32.png") {        console.log('hello');       $('.stLarge[backgroundImage="http://w.sharethis.com/images/facebook_32.png"]').attr("backgroundImage", "url(/images/facebook.png)";     }    It's getting inside the if statement but not executing the image change. Any idea what i have done wrong? Thanks in  advance

I have an image URL in a imageUrl variable and I am trying to set it as CSS style, using jQuery:  $('myObject').css('background-image', imageUrl);   This seems to be not working, as:  console.log($('myObject').css('background-image'));   returns none.  Any idea, what I am doing wrong?


In Ubuntu I can do this in order to add a new group and user:  groupadd group123 useradd -m -s /bin/bash -g group123 user123 usermod -a -G sudo,www-data user123   I was able to do this in FreeBsd:  sudo pw groupadd group123 sudo pw useradd user123 -m -s /bin/tcsh -g group123   But this has failed:  sudo pw usermod -a -G sudo,www-data user123   because the group sudo didn't exist. Why not? doesn't "sudo pw" imply that it must? If not, how to properly add it?

So far I have found four different ways to add a user to the sudoers group and not all methods work in all systems.  Why so many different implementations? What is the best? What is the standard (i.e. work in most systems)?  Different implementations:   Adding the user to the 'wheel' group.  Adding the user to the 'sudo' group.  Editing the file /etc/sudoers Editing the file /etc/sudoers using visudo


I am trying to get Workstation running on a Dell 9550 that has a very high native resolution of 3840x2160. Workstation runs with no apparent problems. However, when I transfer over a VM that has been running full screen on a desktop host with 1920x1080 resolution it comes up on the notebook with very small icons and text that literally requires a mag glass to read.  I have tried changing the host notebook's resolution to 1920x1080 but I cannot find any set of Workstation VM settings that effectively get me back to a usable resolution like 1920x1080. I have tried every combination of these factors in every order I can think of but the VM insists on coming up at the host's native resolution of 3840x2160 (even after I have dropped the host's resolution down to 1920x1080).  When I right click on the VM's Desktop to try to reduce the VM's resolution the mouse clicks don't seem to be where they visually appear to be and I can't find a way to change the VM's resolution.  Can someone explain what I need to do to get Workstation usable on this notebook?

I have a laptop with a 4K (3860×2160) display, but there are a lot of problems. A lot of virtualization programs aren't compatible with 4K resolution.  VMware Workstation and VirtualBox don't support 4K display in the list of the display's resolution. How I can set the resolution of the display in a virtual machine to 4K?


I have 2 flask restful API's . On my localhost, I open up a terminal and run uwsgi --ini /path-to-ini-file1. For 2nd API, I open up yet agan a new terminal and run uwsgi --ini /path-to-ini-file2. In VPS, I have only a single ssh window. How do I run those 2 on terminals in vps using ssh. Should I create a bin/bash script to achieve that? Any suggestion would be appreciated, thank you.

How do I run a program in the background of a shell, with the ability to close the shell while leaving the program running? Lets say my UI is having problems or for some reason, I need to boot up a program from the terminal window, say, nm-applet:  nm-applet   When it's started, it occupies the foreground of the terminal window.  Is there any simple way to run the program in the background without needing to leave the terminal open or have it occupy the whole terminal?  On that note, I did find a way to run programs from the terminal and have it allow for other inputs, by appending an ampersand (&) to the command as such:  nm-applet &   But this isn't much use as any processes started in the terminal are killed once the terminal is closed.


So this year I'm finishing my masters degree in Security of Information Systems, in a third world country University (best in my country but still) , and I might have a chance at a fully funded scholarship in a way better university abroad, I was thinking of getting a second masters degree in robotics, Artificial intelligence or Cognitive systems.  Is it worth it ? with a bachelor degree in Computer science and a masters in SIS do I fulfil the requirements ?   There is also the matter that I'm going to be fully relying on the scholarship's funding, and of course I still can try to apply for a Ph.D scholarship abroad, but I heard it's more difficult to get it.  Getting a PhD in my country would be fairly easy, but that's not something I'm really interested in for several reasons, First the pace and level of research over here is not really that good. Second, I'm thinking an experience abroad might really help me at many levels. And here comes the point I'm not really sure about, does having 2 masters degrees give me a chance at a better job ? or a better chance at getting accepted for a PhD ?   PS : The graduation project I'm working on right now is a mix of Forensics, Security, massive parallel computing and artificial intelligence.   Thank you  EDIT :  Okay, I am to rephrase my question, I'm a passionate learner, I want to have the experience of studying abroad, I enjoy many fields in computer science, my question is, can this actually hurt my career ? personally I don't mind "postponing" its start, as long as it's harmless and I'm doing something I enjoy.

I recently read on stack overflow that getting two PhDs just shows that you're unfocused and you don't know what you want to do. However, I'm at a small school with a 5 year Computer Engineering bachelors/masters program I feel like I should take advantage of, but I'd also like to go on to do another part time grad degree in the same field or Computer Science at a larger, better established school, while I work.   If I went to a larger school like University of Illnois or MIT or similar, will having a masters and going back for another be frowned upon, or is this a non-issue?


Suppose I am travelling at a speed near to the speed of light and I have a clock with me . For a stationary observer having the same clock, he would see that my clock ticks slower than his. On the other hand, when I look at him back, I would see his clock ticks slower than that of mine(as he is travelling at the same speed with respect to me).  So, don't these two time dilations cancel out each other's effect making both our times pass at the same rate (i am travelling and the observer is at rest)? How does the relativity theory explain this?

Suppose we have two twins travelling away from each other, each twin moving at some speed $v$:    Twin $A$ observes twin $B$’s time to be dilated so his clock runs faster than twin $B$’s clock. But twin $B$ observes twin $A$’s time to be dilated so his clock runs faster than twin $A$’s clock. Each twin thinks their clock is running faster. How can this be? Isn’t this a paradox?


Chapter 38 of Mazur and Stein's "Prime Numbers and the Riemann Hypothesis" asks us to prove that if a Gaussian integer is a prime Gaussian integer, then its norm can only be an "ordinary prime number, or the square of an ordinary prime number". $$|G_{\text{prime}}|=p \text{ or } p^2 $$ I have researched other questions and answers on this site and via google but cannot find a simple explanation that I can understand. I'd appreciate an answer that avoids too much terminology. For example, this answer is not clear enough for me as someone not formally trained in mathematics:  Note: the system suggests this is answered here, but the answer doesn't meet the request here for a accessibility to those without formal mathematics training:

Let $a \in \mathbb{Z}[i]$ be a prime element. Show that $N(a)$ is a prime or a square of a prime.   I know that the converse is true. That is, if the norm of $a$ is prime then $a$ is a Gaussian prime. But how do I prove the claim above? Thanks!


The voltage-current equation in a capacitor is given as   $$I(t) = C\frac{dV}{dt}$$  Isn't $\frac{dV}{dt}$ by definition the instantaneous change in voltage with respect to time?  How does one show from this equation that voltage cannot change instantaneously?

Why is the voltage across a capacitor (as a function of time) continuous? Why is the current across an inductor (as a function of time) continuous?


I have such hierarchy of classes for saving entities found in DXF file: class MyDxfItem {    public: DL_Attributes usedAttributes;    virtual ~MyDxfItem() {} }; class MyDxfLayer : public MyDxfItem {     public:     MyDxfLayer(const std::string& name, int flags, bool off = false): LayerInfo(name,flags,off) {      }     public: DL_LayerData LayerInfo;           };  class MyDxfCircle : public MyDxfItem {      public:          MyDxfCircle(DL_CircleData inCircleInfo): circleInfo(inCircleInfo) {          }              public:      DL_CircleData circleInfo; };  class MyDxfArc : public MyDxfItem {     public:     MyDxfArc(DL_ArcData inArcData) : arcInfo(inArcData) {      }     public: DL_ArcData arcInfo; }; class MyDxfLine: public MyDxfItem {     public:         MyDxfLine(DL_LineData inLineData) : lineInfo(inLineData) {      }     public: DL_LineData lineInfo; }; class MyDxfPoint : public MyDxfItem {     public: DL_PointData pointInfo; };  class JovanDxfStruct { public: std::vector<MyDxfItem> MyListLayers; public: std::vector<MyDxfItem> MyListItems; } ;  extern JovanDxfStruct* globalPtrToDxfStruct;  MyDxfLayer is a subclass of MyDxfItem, MyDxfLayer expands and extends MyDxfItem. Base class has virtual destructor. I keep instances of MyDxfLayer in vector: std::vector<MyDxfItem> MyListLayers, it is legal by inheritance. Here is my code how I add item to this vector: if (globalPtrToDxfStruct != nullptr) {         MyDxfLayer layerDataMy(data.name,data.flags, data.off);         layerDataMy.LayerInfo = data;         layerDataMy.usedAttributes = attributes;         globalPtrToDxfStruct->MyListLayers.push_back(layerDataMy);     }  I create here instance of MyDxfLayer and add it to std::vector. But when I try to downcast it back to its original class I get nullptr:  Right after the element was added to array it gets trimmed to baseclass and information stored in instance or derived class seems like lost. Why is this happening? Why the code: dynamic_cast<MyDxfLayer*>(&(globalPtrToDxfStruct->MyListLayers[0]))  returns null? you may see that globalPtrToDxfStruct->MyListLayers[0] is not null. I am adding the instance of derived class to vector of instances of base classes. I have referenced to example from  , there is an example without vector, but I think it should be similar

Someone mentioned it in the IRC as the slicing problem.


I have created a aura lightning component which implements force:hasRecordId.  <force:recordData aura:id="recordLoader"                        recordId="{!v.recordId}"                        fields="Name, OrderNumber__c, test_field_1__c, test_field_2__c "                        targetFields="{!v.opty}"                        targetError="{!v.recordLoadError}" />   I am using above snippet.   Now, I need to retieve field values of fields like OrderNumber__c, test_field_1__c, test_field_2__c in my JS controller without using apex class.   Is there any way to achieve this?

Is there a way we can get the value from force:RecordData on init ? I am getting the onclick event of a button.  <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>     <aura:attribute name="recordId" type="String"/>      <aura:attribute name="showButton" type="Boolean" default="false"/>     <aura:attribute name="Opportunity" type="Object"/>        <aura:attribute name="parentOpp" type="Object"/>     <aura:attribute name="oppLoadError" type="String"/>     <force:recordData aura:id="oppRecordLoader"                       recordId="{!v.recordId}"                       fields="Id,                               Name,                               AccountId,                               Cohort_Sem__r.End_date__c,                               LeadSource,                               Staff_Referral_Detail__c,                               lead_source_detail__c"                       targetRecord="{!v.Opportunity}"                       targetFields="{!v.parentOpp}"                       targetError="{!v.oppLoadError}"                       />   JS:  doInit: function(component, event, helper) {                     var opp = component.get("v.parentOpp");                   console.log('Name Value: '+ opp.Name);     }   Error:     Action failed: c:createIWSRecord$controller$doInit [Cannot read   property 'Name' of null] quickActionHandlerHelper.js failed to create   component - forceChatter:lightningComponent


I have tried to search this and was able to find few but could not find exactly the way to script out the database level permissions for a database.  I am migrating this database whose logins I can create using sp_help_revlogin, but user permissions will not get copied.  I can extract permissions with below query:  SELECT    ISNULL(OBJECT_NAME(major_id),'') [Objects], USER_NAME(grantee_principal_id) as [UserName], permission_name as [PermissionName] FROM     sys.database_permissions p WHERE grantee_principal_id>0 ORDER BY     OBJECT_NAME(major_id), USER_NAME(grantee_principal_id), permission_name   But I need something like rev login which generates a script and you can execute to get the permissions mapped.  I have tried DBAtools, but i am unable to use as it fails with error     Unable to find type [DbaInstanceParameter]   I have more than 50 logins and about 20 roles to be copied.

I have to copy the entire database permissions from database A to database B which has  same objects in database B in same instance.   What are the things that I need to copy from database A to database B to get the same permission as in database A.  Environment: SQL Server 2012 , in same server with same logins.


I made a small circuit using LTSpice and want to try to understand the output. My input is a 1.4V sinewave with a +10V offset (Vin = 10V + 1.4V*sin(2*pift)). The Zener Diode has a Breakdown Voltage of 6.2V   I can see that the Zener Diode breaks down immidiately. Is that caused by the 10V offset ? How can I calculate the peak of the output voltage ?

I have a problem with this homework, I have to calculate the peak voltage of the output after stabilizing with a zener diode.  My Input Voltage is Vin = 5V + 0.7Vsin (2pif*t) with f=10kHz  My circuit is a simple regulator with no load resistor. The series resistance is 82 Ohms, Zener voltage is 3V, max. current through the diode is 33.3mA. How can I calculate the peak output ? My problem is the offset created by 5V, wouldnt the Zener voltage be reached immidiately with this configuration ?         – Schematic created using


I need to run my Python script 200,000 times. Is it possible to do parallel execution using bash? Since it's 200,000 times I would like to use at least 10 threads simultaneously

I have a table URL_Experiment in my database (mySQL database). I have 2 million URL links in this table.  For each URL, I am checking if some particular text is present in the URL and updating the information back in my URL_Experiment table.    Now, I need to make the script run fast. The easy solution that comes to my mind is:  split the URL_Experiment into 10 tables (each with 200,000 rows) and run the script 10 times simultaneously. This way, I can ensure that the updates happen properly. But for this, I need to save 10 scripts, each accessing the correct table (I need to rename the tables from 1 to 10).   Though the above seems a pretty neat solution, I am looking for a more sophisticated solution. Something which will execute the same script simultaneously (in parallel) as 10 processes. My concern is the execution time. I do not want the resources to be wasted when they can be utilized.


My understanding is that GPUs are more efficient for running neural nets, but someone recently suggested GPUs are only needed for the training phase and that once trained, it's actually more efficient to run them on CPUs.  Is this true?

My understanding is that GPUs are more efficient for running neural nets, but someone recently suggested to me that GPUs are only needed for the training phase. Once trained, it's actually more efficient to run them on CPUs.  Is this true?


I am pretty noob on linux and this is probably a very simple error but I can't fix it.  I am trying to install AMD drivers for my card on Ubuntu server 14.04 (for a ethereum miner).  I followed this tutorial from AMD   What I did was the following:  I installed Ubuntu server and connected via ssh from my windows machine.  I checked my Ubuntu version, also checked that it was 64 bit.  I checked my graphics card version:   lspci -nn | grep VGA -> Advanced Micro Devices, Inc. [AMD/ATI] Tonga PRO [Radeon R9 285/380] [1002:6939] (rev f1)   I go to the amd website to download the drivers. they should be under Radeon™ R9 200, R7 200, HD 7000, HD 6000, and HD 5000 Series, I go to the Ubuntu 14.04 64 bit link .  I download the first one (don't know why there are so many) using wget  The problem comes when I try to unpackit (if it's the right word) using the following command:  sudo dpkg -i fglrx_15.302-0ubuntu1_amd64_ub_14.01.deb   I am given an error:  dpkg-deb: error: `fglrx_15.302-0ubuntu1_amd64_ub_14.01.deb' is not a debian format archive dpkg: error processing archive fglrx_15.302-0ubuntu1_amd64_ub_14.01.deb (--install): subprocess dpkg-deb --control returned error exit status 2 Errors were encountered while processing: fglrx_15.302-0ubuntu1_amd64_ub_14.01.deb   I am not able to fix this, please help me. Thank you very much.

I am planning on doing a fresh install of Ubuntu and want to know what is the correct way to install ATI Catalyst Video Driver?      There are multiple valid answers for this question spanning over several versions of Ubuntu. For your convenience an index of each below:


I have a very sticky door lock, is it safe to oil it with standard household oil?  Will oil degrade the security of the lock in any way?  If it's safe, how should I apply the oil?

I recently made the Yale lock on my front door much easier to open by spraying some WD-40 in there.  However, I just saw  on WD-40 not being a “true” lubricant, and wondered whether it was appropriate to use on Yale locks?


Your native country is your / "fatherland",  the land of your ancestors is your  and your first language is your . What do you call the home in which you grew up and spent most of your childhood (any other mother/father-containing word or phrase such as father home, mother home, maternal home, paternal home, or ___)? I want to use it in sentences like these:   "When I was single and still living in my ___, I didn't eat meat food at all, but after getting married I stared to change my habit."  After their parents' death, they sold their house and went to another city and took all of the memories of that ___ with them."    PS: In my country we call it "fatherhome".

For instance, to refer to the place you were born you say "my hometown." How about when referring to the house where you were born? I thought of "my parents' house", but I think it'll sound strange if one of the parents no longer lives there?


I am a Canadian permanent resident / Iranian citizen. I am flying from Canada to the Middle East through Europe. I have 2 stops in Europe. The first one is in Frankfurt and the second one in Vienna. I do not hold a transit visa.  Will I be able to connect through these 2 airports to my destination without a need for a visa?

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


Early today, I logged in to SE, and the top bar (trophy cup icon) showed a rep change of +27. When I pulled it down to see the details, it showed +20 in each of two stacks (three actions - two different answers upvoted in one stack, one answer upvoted twice in a second stack). I went through all of my stacks, and found that the difference (-13) between +40 and +27 was accounted for by a removed question in a third stack.  Can the 'trophy cup' be fixed so that rep decreases are also reported?

The "Recent achievements" icon (looks like a bar graph in the top bar for signed in users) doesn't highlight when one only has recent reputation losses.  I'd like it to highlight whenever my reputation changes, positive or negative - in fact I'd suggest it's far more important for me to review posts that get a downvote than those that got an upvote.  Is there a reason negative reputation events don't cause it to highlight?


Which one of the following sentences is correct?  one or more child  Or  one or more children

Should I use singular or plural after one or more?  Example:      One or more [signal/signals]


When I create new TASKs the "edit" (to save changes) and "delete" links stops working. What it wrong here?  I am using .on() but it doesn't work with new elements.  html:

       <input type="checkbox">Pay Bills       <input type="text">       <button class="edit">Edit</button>       <button class="delete">Delete</button>

   jQuery:   //Add new TASK  $('#addButton').click(function(){  $("#incomplete-tasks").append('
<input type="checkbox">' + $('#new-task').val() + '<input type="text"><button class="edit">Edit</button><button class="delete">Delete</button>
')  });   //Show edit mode  $("#incomplete-tasks").on("click", ".edit", function() {   //show  $(this).parent().toggleClass('editMode');   //Add label value = edit field text  var $label = $(this).children().find('label').text();  $(this).children().find('input[type=text]').val($label);  });   //Save changes when "edit"is clicked again   $('.edit').on("click", function() {  var value = $(this).parent().find('input[type=text]').val();  $(this).parent().find('label').text(value);  });   //delete task   $('.delete').on("click", function() {  $(this).parent().hide();  });   FULL CODE -

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I recently know that there is software viz. SANE [Scanner Access Now Easy] which can automatically detect printer (almost all the printer) and one can easily scan via this software. So I search for that and find a page  and from this page, I get a command to install SANE. The command is      sudo apt-get install sane sane-utils libsane-extras xsane   But while running this command in the terminal, it gives some errors and installation is not done.  The error message is shown in the picture.  Can anyone tell me how to solve it.

I get this error when trying to use apt-get:  E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?     How can I fix this?


Consider $a_1,\ldots,a_n\in \mathbb Z$.  i) Suppose $a_1,\ldots, a_n$ are pairwise relatively prime. I have to see by induction on n that $[\mathbb Q(\sqrt a_1,\ldots,\sqrt a_n):\mathbb Q]=2^n$  Once I proved the equality is true for $n=1$, I suppose it is true for $n-1$, so let's prove it for $n$: Applying the tower law: $[\mathbb Q(\sqrt a_1,\ldots,\sqrt a_n):\mathbb Q]=[\mathbb Q(\sqrt a_1,\ldots,\sqrt a_n):\mathbb Q(\sqrt a_1,\ldots,\sqrt a_{n-1})] [\mathbb Q(\sqrt a_1,\ldots,\sqrt a_{n-1}):\mathbb Q]$  By induction, $[\mathbb Q(\sqrt a_1,\ldots,\sqrt a_{n-1}):\mathbb Q]=2^{n-1}$  So we only have to see that $[\mathbb Q(\sqrt a_1,\ldots,\sqrt a_n):\mathbb Q(\sqrt a_1,...,\sqrt a_{n-1})]=2$  $[\mathbb Q(\sqrt a_1,\ldots,\sqrt a_n):\mathbb Q(\sqrt a_1,\ldots,\sqrt a_{n-1})]=[\mathbb Q(\sqrt a_1,\ldots,\sqrt a_{n-1})(a_n):\mathbb Q(\sqrt a_1,\ldots,\sqrt a_{n-1})]=deg(Irr(\sqrt a_n,\mathbb Q(\sqrt a_1,\ldots,\sqrt a_n))$  $Irr(\sqrt a_n,\mathbb Q(\sqrt a_1,\ldots,\sqrt a_{n-1})=X^2-a_n??$  I have to see that  $\sqrt a_n \notin Q(\sqrt a_1\ldots,\sqrt a_{n-1})$. By contradiction,  if$ \sqrt a_n \in Q(\sqrt a_1,\ldots,\sqrt a_{n-1}) \to \sqrt a_n= a+b\sqrt a_{n-1}$ where $a,b\in Q(\sqrt a_1,\ldots,\sqrt a_{n-1}$. How can I get to a contradiction???  ii) Consider $P$ the set of prime numbers and $F$ an extension of $\mathbb Q$: $F=\mathbb Q (\sqrt p,  p\in P)$ Which is the degree of $F/\mathbb Q$? Is it finitely generated?  Could you help me with this problem please?  Thank you for your time and help.

I need to find a way of proving that the square roots of a finite set    of different primes are linearly independent over the field of    rationals.    I've tried to solve the problem using elementary algebra  and also using the theory of field extensions, without success. To  prove linear independence of two primes is easy but then my problems  arise. I would be very thankful for an answer to this question.


Seems like the best piece of equipment for a sport that is played professionally and has such a big public following probably costs quite a bit. Did McGonagall buy it in a private capacity or perhaps with funds available to her as head of house?

The Nimbus 2000 was the fastest broom at the time of the Harry's first year at Hogwarts.  Professor McGonagall wanted to win the Quidditch Cup so she spoke with Dumbledore and got an exception from the rule that no first-years could have a broom for Harry.  My question is who paid for the broom?  It couldn't have been a cheap broom.  They wouldn't have taken gold out of Harry's Gringotts account without permission.  It wouldn't be right for the school to pay for it and I doubt McGonagall paid for it out of her own pocket.  So who paid for the broom?


I came here to ask "how can we encourage people to upvote questions?".  In the space where I ask and answer (wxpython) there is nine times out of 10 that I come here (daily) a first page of questions with zero or 1 answer, and the only upvoter on any of those questions is me.  I read here at meta a lot of questions about "how can we encourage upvoting?", and many of these are voted down due to people not liking the proposed solution/  But one key point emerges: we collectively don't appear to have a good handle on why upvoting of questions is there.   Or at least, I can't get a clear answer on that which is consistent with the way that it works.  So - what is the purpose of having questions be upvoted?  Just to be clear: I understand what an upvote means.  It means "I think this is a good question".  What I'm not clear on is what is the purpose of this facility in SO?   What is it intended to achieve for the site?    I want to be clear on this, before I think too much about the real thing that was concerning me, which was how to encourage people to vote in this way.  Thanks.  Edit: reponding to "possible duplicate of 'why should I upvote?'", I view this question as different.   That question was "what are the guidelines for upvoting".   My question is "what are the effects that SO wants to achieve with upvoting".  It was observed in comments that the answer to this question is self-evident.   I don't agree.   Possible answers are:  1) To encourage good questions  2) To provide users with a means of getting reputation  3) To make good questions more visible  4) To alert people to not bother looking at bad questions  5) To support decision making algorithms behind the scenes.  I am interested to know what out of these are the primary reasons for making it possible to vote for questions.  What does the SO community view as important objectives.   Because depending one which of these is important, the means by which we would choose to encourage people to upvote questions might be different.  My own observation is that there is no real problem with people downvoting questions - they do this, and achieve objective 4 already.  However, at least in the space of questions where I participate, upvoting good questions is rare, which is what makes this question pertinent.

What are the actual effects of voting on questions? All the documentation I could find just says that voting "moves things up" and "gives people reputation". I get the second part, and I get how voting "moves things up" for answers, but how exactly does voting move things up for questions? Does it make them appear higher on the main page? On in-site search results? On Google search results?


I am getting the icon that means, "This page is trying to load scripts from unauthenticated sources" no matter what page I am on in Chrome. For example, even in just the Google search page I have that icon. I have also been misdirected very often lately to a screen that starts beeping out loud like an emergency notification and tells me that I have a virus and I should call a certain number etc and that I should not shut off my computer or it will not work etc. (with an actual voice recording that comes on).  I have MacAfee through my internet provider and scans show no problems. How do I fix all this. I am not a computer expert.

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


Is it possible to handle a JSON response using plain Ajax (i.e. JavaScript, without JQuery)?  In this description:   only Text and XML objects are mentioned, but how to handle a JSON respone?  I just want to use pure JavaScript, without any additional libraries.  This shows me the JSON respone:  console.log(xhttp.responseText);

Given a string of JSON data, how can I safely turn that string into a JavaScript object?  Obviously I can do this unsafely with something like:  var obj = eval("(" + json + ')');   but that leaves me vulnerable to the JSON string containing other code, which it seems very dangerous to simply eval.


I want to show that for $n\times n$ matrices $A,B$ that $\text{det}(I-AB)=\text{det}(I-BA)$.  My thought is that since $AB$ and $BA$ have the same eigenvalues, I know they have they same minimal polynomial. If I can further show they have the the same characteristic polynomial, I'm done.  Is that true though? the characteristic polynomials for $A$ and $B$ respectively are $P_A(x)=(x-\lambda_1)^{c_1}...(x-\lambda_j)^{c_j}$ and $P_B(x)=(x-\lambda_1)^{d_1}...(x-\lambda_j)^{d_j}$ where $\lambda_q\neq\lambda_p$, $j\leq n$ and the superscripts are the dimensions of the the generalized eigenspaces. Is it true that $c_k=d_k?$

assume $A,B\in M_n(F)$ if  $I-AB$ be  invertible then  how  to prove $I-BA$ is invertible and how find inverse of $I-BA$   Thanks in advance


I'm running a multiple linear regression in R.  In my linear regression I have 'country' as a qualitative predictor, which dramatically increases the adjusted R^2 value, and lowers my BIC. I want to include it in my regression model, but only around 2/3 of the counties I've mentioned are statistically different from the dummy variable.   Is it correct to bundle these countries together to have "zero" weight when compared to the dummy variable?  When I run my training model on some test data, how can I stop it using these from adding 'artificial statistically insignificant weights' to the model.  For example, Australia adds 2.6 to the model, but its p value is 0.34. I would like it to add 0 instead of 2.6.  Thank you very much!

After seeking clarification about linear model coefficients  I have a follow up question concerning non-signficant (high p value) for coefficients of factor levels.  Example: If my linear model includes a factor with 10 levels, and only 3 of those levels have significant p values associated with them, when using the model to predict Y can I choose to not include the coefficient term if the subject falls in one of the non-signficant level?  More drastically, would it be wrong to lump the 7 non-significant levels into one level and re-analyze?


Is there anyway we can get when list item updating in sharepoint designer workflow?. I have status ="New" it is need to send only one time when new item created.  But now it is sending emails when item is updating with status="New". So I want check if it is new then only check status="New" and send email. otherwise No.

Is there any way of identifying if my SPD (2010) workflow was initiated by item creation or by item modification? I don't want to split the workflow into two as 99% of the workflows would be identical.


In fiction, (notably Ernest Cline's novel Armada and Charles Stross's books Singularity Sky and Iron Sunrise) Quantum Entanglement is used for long distance communication.  In reality, given our current understanding, how feasible is this?   Is Quantum Entanglement potentially predictable enough and stable enough to act as a method of communication? I understand that our current level of technology might not be sofisticated enough to create such a device today (please correct me if I am wrong).  I am wondering if our current understanding of Quantum Entaglement today suggests that such a device may be possible in the future?  Or does our current understanding indicate that such a device would only be possible in the realms of fiction?

As I understand it (from a lay physics perspective), quantum entanglement has been experimentally demonstrated - it is a reality. As I understand it, you can measure something like the spin of an electron and know that its entangled pair will, in that same instant, no matter where in the universe it is, have the opposite spin.   This would not seem to have any utility as the foundation of a superluminal communications device. Is this true, or has it been established that is there some aspect of quantum entanglement that can ultimately lead to the development of such a device.  In other words: is superluminal communication via quantum entanglement an open scientific question, has it been settled as an impossibility, or is it currently more of an engineering problem than a scientific one?


It was a series of 3 or 4 books.  The crew of a ship were on a mission to recover something ( rings I think) from different planets.  Humans had been genetically altered to live on each planet.  Volunteers were permanently altered to blend in on the planet to complete their missions.

I'm looking for a series of books that deals with humans escaping Earth and having a mother ship full of humans who are being sent throughout the universe to different planets. The ship can transform the humans into whatever type of alien the planet holds. One set of sisters is transformed to cow-like aliens and sent to spy on that planet. All the while the group that's taken the mother ship full of human colonizers is trying to evade/escape the government people from Earth.    The 9 or 10 humans who steal the colonizing ship drop a couple of humans (transformed to whatever the indigenous species is) to the planet to spy...the end result is to try and overthrow the Earth government.  The humans that the colonizing ship transform to aliens cannot be turned back into humans ever again so when they take on the assignment to spy they do so knowing that they won't ever be able to be humans again.


I'm trying to select a mechanics book for self-study. I have some math background (linear algebra and calculus among other things) and I want to pick a book that won't skip over the math. I would prefer something more rigorous and thorough. I see the names Taylor and Goldstein come up quite frequently and so I would like some help in understanding the differences between their books.

I am looking for a book about "advanced" classical mechanics. By advanced I mean a book considering directly Lagrangian and Hamiltonian formulation, and also providing a firm basis in the geometrical consideration related to these to formalism (like tangent bundle, cotangent bundle, 1-form, 2-form, etc.).  I have , but I would like to go into more details about the [symplectic] geometrical and mathematical foundations of classical mechanics.  Additional note: A chapter about relativistic Hamiltonian dynamics would be a good thing.


I'm learning Cpp from the basics, and when learning structure padding and data alignment, confused with the following:  struct A { char a; double b; char c; };  struct B { char a; short b; char c; };   Using MSVC++ 14.0 32 bit compiler  I understood the concept of data alignment by referring various pages on web.  In the 1st case, the sizeof(A) will give "24 (1 (a)+7(padding)+8(b)+1(c)+7(struct padding - since double is the max sized variable, padding is used to that value (8-1))". Here, I understood that because of cache lines (usually 32/64 bytes), double of 8 byte size is started at a location, which is a multiple of 8 instead of a multiple of 4 (even though compiler is 4 byte long - either case it requires 2 memory cycles but to avoid the data being split across 2 cache line location which is multiple of 8 is chosen)  But in the 2nd case, the sizeof(B) yields "6 (1(a) + 1(padding) + 2(b) + 1(c) + 1(padding)". This is of course the expected value from the rule (value of x bytes starts at a location which is multiple of x). But here, I did not understand why there is a need for b to start at a location which is multiple of 2?  Assuming that in struct B, a is placed at 0x00, why can't b placed at 0x01 and c at 0x03? Even in this case, the value of any of the variables (a,b or c) can be fetched in a single memory cycle (since 4 byte compiler) and this also doesn't result in 2 cache lines. I didn't understand the use of padding in this case.  Please help!!! I'm just curious to know, what advantage padding adds here?

Why does the sizeof operator return a size larger for a structure than the total sizes of the structure's members?


I am trying to get an element from a list List<Class> listofitems, and I have a globale variable position of type long. I would like to perform listofitems.get(position) but it doesnt allow me to do so since get takes int as argument. If I want to keep the type of position as long, if there are any other way to do this? (any other way besides casting position to int)?

I am writing this java program to find all the prime numbers up to num using the Sieve of Eratosthenes, but when I try to compile, it says I can't use a long var as an array index, and it expects an int var in its place. But I'll be working with large numbers, so I can't use int. What can I do?  import java.util.*; import java.lang.*;  public class t3{     public static void main(String[] args){         long num = 100;          //declaring list and filling it with numbers         ArrayList<Long> numlist = new ArrayList<Long>();         for(long x=2 ; x<num ; x++){             numlist.add(new Long(x));         }          //sieve or eratosthenes         for(long x=0 ; x<Math.sqrt(num) ; x++){             for(long y=x+1 ; y<numlist.size() ; y++){                 if(numlist[y]%numlist[x] == 0){                     numlist.remove(y);                 }             }         }          //print list         for(Object item : numlist){             System.out.println((Long)item);         }     } }


How do I make something like the picture above.

So uh i've got this problem with a penetrating object and another object that serves as something like a condom if you will    So what I want, is for the penetrating object to not deform while moving into this "rubber cylinder", while the rubber cylinder does deform and reshape itself to the outer form of the penetrating object. That is, if the pen. object is bigger than the entrance hole ofc.  Also, when the object leaves the "rubber cylinder" I want the outer edges to follow (mid object in picture) and then jump back (right object in picture)    Parenting the size and position of the "rubber cylinder"-entrance to the position of the penetrating object would work i guess, but I think it'd create problems when the pen. object enters from another angle (not perpendicular to the entrance). I just read another post where someone mentions Vertex Weight Proximity modifier in a combination with a cast modifier. Don't know if thats gonna work yet. Couldn't find the time to test it.


I have two MySQL insert statements on my site.  If I insert a £ sign into $data through this statement it goes in as a £ - which is fine.  $query = "INSERT INTO `applicants` (`id`, `data`, .....)  VALUES ('0', '".addslashes($data )."',... ";    In the second statement the £ in $data goes in as Â£ The insert statement is   $stmt = $conn->prepare('INSERT INTO applicants SET    `data` = :data, ........   $stmt->bindParam(':data', $data);      Might the Â£ problem be caused by the way $stmt / bindParam insert statement?

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


I am a novice. I accidentally ran a command  sudo chown www-data:www-data -R /  Now mysql is not working.   Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)  Please help.

I accidently ran  sudo chmod 755 -R /   instead of  sudo chmod 755 -R ./   I stopped it after few seconds, but now there is some problems such as  sudo: must be setuid root   How can I revert permissions back?


Stack Exchange is my role-model for application development.  I've tried to learn as much as possible from the blog and podcasts, from thought process to design, architecture, convention, etc etc.  I'm just about to wrap my head around TDD and am curious about how the SE team approaches it.  Is there a methodology that all team members follow, or is it more developer-driven testing where you pick complex bits to unit test as needed, or is it more about catch-all integration testing once a piece of functionality is done, or... ?  Any input would be fantastic.

I'm just curious. Is Stack Overflow built with  (or , , etc.)?  Can you guys say something more about code infrastructure?


Am I missing something basic or is this a bug ?

In the get info window it says 387,037,139 bytes which is 387 MB whereas the size on disk is 716.9MB which is 716,900,000 bytes.   du -sh paramgen  result (in MiB) 684M    paramgen  Why is there such a large difference?