Can not upload photos: NullReferenceException
What is a NullReferenceException, and how do I fix it?
Was or is? Confusion How to calculate overlap between empirical probability densities? I'm looking for a method to calculate the area of overlap between two kernel density estimates in R, as a measure of similarity between two samples. To clarify, in the following example, I would need to quantify the area of the purplish overlapping region:  library(ggplot2) set.seed(1234) d &lt;- data.frame(variable=c(rep("a", 50), rep("b", 30)), value=c(rnorm(50), runif(30, 0, 3))) ggplot(d, aes(value, fill=variable)) + geom_density(alpha=.4, color=NA)     A similar question was discussed , the difference being that I need to do this for arbitrary empirical data rather than predefined normal distributions. The overlap package addresses this question, but apparently only for timestamp data, which doesn't work for me. The Bray-Curtis index (as implemented in vegan package's vegdist(method="bray") function) also seems relevant but again for somewhat different data.  I'm interested in both the theoretical approach and the R functions I might employ to implement it. How to solve differential equations of the form $f'(x) = f(x + a)$ What could one do to find analytic solutions for $f'(x) = f(x + a)$ for various values of $a$?  I know that $c_1\sin(x + c_2)$ is solution when $a = \frac{1}{2}\pi$, and of course $c_1e^x$ when $a = 0$.  For instance, is there a function satisfying $f'(x) = f(x + 1)$?  What about negative or imaginary $a$?  Is there possibly a generalization? Film where aliens looking like humans are waiting in an airport closed due to snowstorm I saw the movie 6 - 7 years back on cable tv, from the looks of it it seemed to be made in the late 1990's or early 2000's. Unfortunately I could not see the complete movie. The story goes like--   Some people are waiting at a small airport because snowstorm activity has cancelled all flights in and out. There are two children in the group as well (one boy and a girl). Somehow they discover there are aliens looking like humans among them. They decide to check passengers through baggage scanners (checking the skeletal structure via x-ray). They find and kill 2 aliens.   and the big twist:      5. They then realize the two children are also aliens.   any ideas what the name of the movie is ??? What is the greatest integer that divides $p^4-1$ for every prime number $p$ greater than $5$? What is the greatest integer that divides $p^4-1$ for every prime number $p &gt; 5$?  This was on a practice math GRE so it's probably really easy. Implicit newline at the end of each paragraph? At the moment, I have created a code that retrieves data from the database and displays it. However, for some reason, I cannot see the files I want to retrieve on my page. My goal is that the data gets retrieved from the database, and is displayed on the webpage. I do not need to make a connection with the database since Wordpress does that automatically.  My code:  &lt;?php  global $wpdb; // this adds the prefix which is set by the user upon instillation of wordpress $table_name = $wpdb-&gt;prefix . "wpex_programma"; // this will get the data from your table $retrieve_data = $wpdb-&gt;get_results( "SELECT * FROM wpex_programma; " ); print_r($retrieve_data); ?&gt; &lt;ul&gt; &lt;?php foreach ($retrieve_data as $retrieved_data){ ?&gt; &lt;li&gt;&lt;?php echo $retrieved_data-&gt;column_name;?&gt;&lt;/li&gt; &lt;li&gt;&lt;?php echo $retrieved_data-&gt;another_column_name;?&gt;&lt;/li&gt; &lt;li&gt;&lt;?php echo $retrieved_data-&gt;as_many_columns_as_you_have;?&gt;&lt;/li&gt; &lt;?php  } ?&gt; &lt;/ul&gt;   My question: the data is not shown and I believe it is not retrieved. How can I fix that? The table name is correct, and I have data in my database tabel. The print_r($retrieve_data)returns the following: Array ( [0] =&gt; stdClass Object ( [id] =&gt; 35 [naam] =&gt; /public_html/wp/wp-content/plugins/AbonneerProgrammas/FilesUpload/Country Kickin 1.mp3 ) )  My query log:    My database structure:   New:  &lt;?php  global $wpdb; // this adds the prefix which is set by the user upon instillation of wordpress $table_name = $wpdb-&gt;prefix . "wpex_programma"; // this will get the data from your table $retrieve_data = $wpdb-&gt;get_results( "SELECT * FROM wpex_programma; " ); print_r($retrieve_data); ?&gt; &lt;ul&gt; &lt;?php foreach ($retrieve_data as $retrieved_data){ ?&gt; &lt;li&gt;&lt;?php echo $retrieved_data-&gt;id;?&gt;&lt;/li&gt; &lt;li&gt;&lt;?php echo $retrieved_data-&gt;naam;?&gt;&lt;/li&gt; &lt;?php  } ?&gt; &lt;/ul&gt; Wrong nameserver set by resolvconf and NetworkManager What rules govern forced removal from flights (due to overbooking)? I was recently surprised to see  because his flight was overbooked.  He was reportedly a doctor who needed to see patients the next morning, so he did not really want to get off, justifying the use of force.  I knew that airlines could overbook flights and deny boarding to some passengers, but I thought that kind of boarding denial would happen at the gate and that once folks had been let on, those denied boarding would be those arriving later to the gate.    Why or in what conditions is this kind of forcible removal considered OK?    Clarification following close votes from people who think this question is primarily opinion-based: By "OK" I mean the sense of "legally OK," "officially accepted," "instantiated as policy," "sanctioned by authorities," or "OK according to the regulations and policies and laws and whatever other formal rules govern forced removal from flights due to overbooking." Whether or not you personally consider it socially acceptable does not matter as an answer, unless you have formalized that into a citeable adopted form that governs what happens and want to explain the reasoning behind that rule. In $\mathbb{R}^n$, locally lipschitz on compact set implies lipschitz I need to prove:  Let $A$ be open in $\mathbb{R}^m$, $g:A \longrightarrow \mathbb{R}^n$ a  locally lipschitz function and $C$ a compact subset of $A$. Show that $g$ is lipschitz on $C$.  Can anyone help me? How to stop kernel messages from flooding my console? I'm using Centos 6, rsyslog logging. Console is flooded with kernel messages.  Klogd is not running (I'm using rsyslog) Rsyslog config does not direct anything to the console Even tried stopping rsyslog altogether  Still something is flooding my console with kernel log messages. What it is and how do I make it stop? Update: These are the messages generated by the kernel (hardware, iptables, etc.), stuff that goes out of /proc/kmsg, like this:  Shorewall:pub2loc:DROP:IN=br0 OUT= MAC=xxx SRC=xxx DST=xxx LEN=60 TOS=0x00 PREC=0x00 TTL=128 ID=15731 DF PROTO=TCP SPT=63767 DPT=3493 WINDOW=8192 RES=0x00 SYN URGP=0 Can you create a strong blockcipher with small blocksize, given a strong blockcipher of conventional blocksize? Suppose I want a strong 20-bit blockcipher.  In other words, I want a function that takes a key (suppose the key is 128 bits), and implements a permutation from 20 bits to 20 bits.  The set of permutations should be close to a randomly-chosen subset of size $2^{128}$ of all $2^{20}!$ permutations on 20 bits.  I don't want you to build a new blockcipher from scratch.  Instead, assume you have a "strong" blockcipher like AES (128-bit blocksize, 128-bit keysize) and use this to build your 20-bit cipher.   Of course, your construction should be practical (i.e., you should be able to run it in both directions with reasonable amounts of time and memory). Using dconf-editor I tried enabling   org -&gt; gnome -&gt; nautilus -&gt; list-view -&gt; use-tree-view     but even after the check box is selected, plus a reboot, it still doesn't switch to the tree view on the side bar.  In previous versions of Nautilus / Ubuntu the side-pane-view setting used to be in the window-state section (which is now missing)    I'm I missing something, or is there no way to enable Tree View on the side bar in 14.04?  Is there a way to manually create the missing entry back in window-state ? Animations with movie15 and swf files I am trying to use movie15 to embed vector animations in my presentation. The trouble is that embedded SWF files refuse to display on Acrobat Reader X sometimes with a "This Media requires an additional player" message. Eg. this  doesn't work. Animated GIFs won't display either, with no error message.   Maybe this is an Acrobat issue but I tried the flashmovie package with the same SWF files and that does work (but only with the embedded player option so no controls are visible). But flashmovie is supposedly unstable with beamer so I was wondering if someone had run into the same problem with movie15.  I am using Windows 7, Acrobat 10.1.2 and MiKTeX. Ambiguity of "quite" The adverb "quite" has the following meanings :     1: wholly, completely ("not quite   finished")      2: to an extreme : positively "quite   sure" —often used as an intensifier   with a "quite a swell guy" "quite a   beauty"      3: to a considerable extent : rather   ("quite near")   My understanding is that #1 and #2 conflict with #3. For example, when you say "She's quite right", do you mean "She's completely right" or "To a considerable extent, she's right"? Notice that in the latter case you're not saying that she is completely right.  Another example is "I'm quite sure". Does it necessarily mean "I'm completely sure"?   Does the word really have conflicting meanings that can possibly cause ambiguity? Or am I missing something? The system L0 is defined as follows:  Axioms: A1 (α → (β → α))  A2 2. (α → (β → γ) → ((α → β) → (α → γ))  A3 ((¬β → ¬α) → ((¬β → α) → β))  In one of my problem sheets, I am told that I am allowed to use the following theorem: if   ⊢ (α → α)    ⊢ (α → α) → (α → α)  My attempt to solve/prove the second one  ⊢ (α → α) → (α → α) choose 2 axioms which match.  α →α   β→α  γ→α  (α → (α → α) → ((α → α) → (α → α))  I'm struggling to see an obvious way of proving the theorem.  Is it provable? And if so, can you point me in the right direction?  Thanks a lot! Define $\sigma(m) = \sum$ d : d|n.  Prove that $p^j$$q^i$ cannot be a perfect number for $p, q$ odd, distinct primes.  Attempt at Solution: I have shown that $p^k$ can never be a perfect number, and im trying to use the multiplicative property of $\sigma$ to generalize to $p^j$$q^i$ Change the default-view of Media Library in 3.5? When inserting media into a post, is there a way to change the default-view of the Media-Library from "All media items" to "Uploaded to this post"?    There is another thread where this question was extracted from: Why Java needs Serializable interface? What are the possible catch bonuses and how much experience do they reward? I found , earlier, and found out that I can throw a curveball at pokémon to earn an increased experience bonus.  I have since noticed two more bonuses: "Great" and "Nice". I had assumed the bonuses were for throwing a pokéball with the 'catch circle' closer to the center, which according to the FAQ, increases the chances of actually catching the pokémon.  However, I have since noticed that the 'catch circle' is actually bigger in cases where I have earned a "Great" bonus. Despite appearing to be a less powerful throw, I earn more experience than when I earn a "Nice" bonus. "Great" nets me 50 experience, while "Nice" only nets 10 experience.  What are the possible catch bonuses, and how much experience do they reward?  For bonus points, every so often I am awarded an additional 10 experience points that are not accounted for on the experience screen. The screen lists my bonuses, and tells me how much experience I have earned, but I am clearly rewarded additional experience when it is added to my player. Assuming this is another catch bonus, what could this be?