Attempt to invoke interface method on a null object reference finishComposingText()
What is a NullPointerException, and how do I fix it?
Conventions for function notation I'm in year 11 right now and I just had a brief discussion with my maths teacher about function notation in trigonometry.  For a test, I wrote this,   sin(50)^2   I assumed that would be interpreted as sin(50)*sin(50)  But I was told the correct notation for this is is  sin^2 (50)   or optionally  (sin (50))^2   I'm curious if that is the 'proper' mathematical convention, or just how things are taught in high schools?  I'm Australian, in case there are some regional differences.  Thanks for the help! what does the ldapadd error: "additional info: objectClass: value #2invalid per syntax mean? While CtrlX works fine in vim under windows, CtrlA selects all (duh).  Is there a way to increment a number with a keystroke under windows? I want to know the general formula for $\sum_{n=0}^{m}nr^n$ for some constant r and how it is derived.  For example, when r = 2, the formula is given by: $\sum_{n=0}^{m}n2^n = 2(m2^m - 2^m +1)$ according to   Thanks! Can any one tell me the advantage of synchronized method over synchronized block with an example? How to shrink Windows 7 boot partition with unmovable files Any idea why the piece of code below does not add the script element to the DOM?  var code = "&lt;script&gt;&lt;/script&gt;"; $("#someElement").append(code); Clipping image with Basic (ArcView) level license of ArcGIS Desktop? Is there a way to trim a geo-referenced air photo to an irregularly shaped boundary?    I tried the clip tool shown in my attachment, but it didn't work.  It looks as though the output extent field requires a rectangularly shaped polygon as the clipping feature.    Can I even do this in ArcView?    I've never had a request to do anything like this before.        I do use Photoshop and other similar software packages.  I could just go in to an environment like this &amp; start painting everything outside of my boundary in white, but then I would have to come back in and geo-reference the image again, and it just strikes me that there must be a faster and easier way (even though I only have ArcView 9.3). How did Jaqen H'ghar get caught? Following a recent 9gag post:    Did Jaqen H'ghar end up in that cage because he knew that he would meet and "recruit" Arya, or was it some strange coincidence? Is it described somewhere in the books, or left unexplained? I'm wondering a point about N'Zoth. He will summon my dead deathrattle minions, but will he do it in a specific order (death order, mana cost order, ...) ? Or randomly ?  If there is already a few minions on my side of the board, I'd like to predict which minions will be summoned and which ones will not (because board is full). If it's by death order, this generally means lower cost minions (like fire bat) will be summoned before the interesting big drops (sylvanas, highmane or so). I am trying to perform stepwise regression for variable selection in R.  In matlab, the stepwisefit function is able to work in n &lt; p problems. Trying to use step() for such problems i get the error message AIC is -infinity for this model, so 'step' cannot proceed. Is there a way to modify parameters so i can use step function? Reproject GeoJSON from EPSG:3857 to EPSG:4326 I am using this  to convert a GeoJSON point from EPSG:3857 to EPSG:4326.   My command fails. What am I doing wrong?   $ echo '{"type":"Point","coordinates":[-13720479.997764934,5688254.733325758]}' | reproject --from=EPSG:3857 --to=EPSG:4326   /usr/local/lib/node_modules/reproject/cli.js:98             throw new Error("Could not find definition for CRS \"" + crsName + "\".");                   ^ Error: Could not find definition for CRS "EPSG:3857".     at lookupCrs (/usr/local/lib/node_modules/reproject/cli.js:98:10)     at Object.&lt;anonymous&gt; (/usr/local/lib/node_modules/reproject/cli.js:25:1)     at Module._compile (module.js:456:26)     at Object.Module._extensions..js (module.js:474:10)     at Module.load (module.js:356:32)     at Function.Module._load (module.js:312:12)     at Function.Module.runMain (module.js:497:10)     at startup (node.js:119:16)     at node.js:901:3 give space above and below a DIV Can "mustn't" be used for conclusions? I heard this sentence in an American film a while ago as I was watching it on DVD (the part after but is verbatim):  "I'm doing my best but I mustn't be doing it right."  This is something I occasionally hear in American films: phrases like "he mustn't have done it" or "she mustn't be studying now", where a logical conclusion is expressed. So far I've thought that the normal thing to say is "he can't have done it" or "she can't be studying now".  My question is: Can mustn't be used to express a logical conclusion when the speaker is certain that something didn't happen or isn't happening, at least in informal speech? Is this an American usage? (I've never heard this usage in British English, but this doesn't mean it doesn't exist.) Is there a change going on in the usage of the particular modal verb?  Note: All the references I've checked don't even mention this use of mustn't. Google books aren't of help either.   EDIT: I should clarify that I'm asking this question because if I wanted to express that I'm certain I'm not doing something right (as in the sentence quoted from the film) I'd say "I'm doing my best but I can't be doing it right". I would think that the use of mustn't/must not wouldn't be standard usage (although the meaning is perfectly clear to me; I never mistook it for an injuction). “...than I am” vs. “...than me” I read an English grammar article in which the author talked about the correct use of pronouns.  He writes:     If the extended sentence is “She’s more likely to ask him than I am,” in which the comparison is between the subject and the writer, I is correct. However, if the intent is to convey that the man referred to as him is more likely to be asked something by the subject than the writer is, the correct pronoun form is me, but that distinction should be clarified with a revision like “She’s more likely to ask him than ask me.”   Before reading this piece, I thought that the two sentences had the same meaning. While the second example is quite clear for me (“She’s more likely to ask him than ask me”), I don't think that I have correctly understood the first one. Could anyone explain it to me, please? I am working on a BLDC sensorless motor. I need to detect BEMF Zero-cross event. My Motor is working on 24 Volt power.  Now I need to detect the back E.M.F. As refered in .  My MCU is working on 5V. And ADC range is 0 to 5V. I need to convert the BEMF feedback signal to ADC channed in this.  As we know voltage divider rule says:   In Figure I :-- Now signal (U) which I need to feed is applied at the middle of the two resistors R1 &amp; R7. So what is the value of voltage VU ?   In Figure II :-- Sum of U,V,W  is applied at the middle of the two resistors R11 &amp; R15. So what is the value of voltage VN ?  Also, what are the roles of capacitors C1 &amp; C4?  Please can someone explain the MATH behind this ? If $Ax = Bx$ for all $x \in C^{n}$, then $A = B$. Let $A$ and $B$ are $n\times n$ matrices and $x \in C^{n}$.  If $Ax = Bx$ for all $x$ then $A = B$. To prove this I have selected  $x$ from Euclidean basis B = {$e_{1},e_{2},...,e_{n}$}. Then $Ae_{i} = Be_{i}$ implies $i^{th}$ column of A = $i^{th}$ column of B for all $1 \leq i \leq n$. Hence $A = B.$    Is this proof complete? What does Superman do with his regular clothes after changing in the phone booth? We all know that Superman changes in the phone booth. But where does he put his regular clothes while he's on a mission? He doesn't throw it out, because he changes back. But we don't see him carrying a bag of dirty laundry while he's on a mission.  ("In his right hand, Superman has Lois Lane, and in his left hand he seems to be holding... boxers??)  And I can't imagine he leaves it in the phone booth.  So where does Superman leave his regular clothes after he changes? I want to be able to have LinkedList.contains() return true for a custom comparator.  Suppose that I have 1 LinkedList and 2 objects  LinkedList&lt;MyObject&gt; myList = new LinkedList&lt;MyObject&gt;();  MyObject a = new MyObject("HELLO"); MyObject b = new MyObject("HELLO");   Technicaly, both objects are identical in terms of comparison (MyObject implements Comparable)   ( a == b ) == true  however, when I do the following, myList does not return true for myList.contains(b)  myList.add(a) myList.contains(b) // == false   I think its because contains will check object reference and see that a and b are 2 distinct objects. Is there any way I can make it so I don't have to extend LinkedList to compare those objects? How to delete a non-empty directory in Terminal?