Exception in thread main with no errors in Netbeans
What is a NullPointerException, and how do I fix it?
Wine or virtual machine (VirtualBox) to run apps (eg. Photoshop) I am wondering if it will be better (stability, convenience and speed) to run apps like Photoshop with Wine or a virtual machine like VirtualBox? Given Newton's third law, why is there motion at all? Should not all forces even themselves out, so nothing moves at all? When I push a table using my finger, the table applies the same force onto my finger like my finger does on the table just with an opposing direction, nothing happens except that I feel the opposing force. But why can I push a box on a table by applying force ($F=ma$) on one side, obviously outbalancing the force the box has on my finger and at the same time outbalancing the friction the box has on the table? I obviously have the greater mass and acceleration as for example the matchbox on the table and thusly I can move it, but shouldn't the third law prevent that from even happening? Shouldn't the matchbox just accommodate to said force and applying the same force to me in opposing direction? I know $[0,1]$ denotes the interval between 0 and 1 with the boundary. And $(0,1)$ denotes the interval between 0 and 1 without the boundary. Today, I encounter some expressions as $]0,1]$, $]-\infty,+\infty]$. What does $]0,1]$ mean? Thanks. Remove entire row in a file if first column is repeated I have a file containing two columns and 10 million rows. The first column contains many repeated values, but there is a distinct value in column 2. I want to remove the repeated rows and want to keep only one using awk. Note: the file is sorted with values in column 1. For example:    1.123 -4.0 2.234 -3.5 2.234 -3.1 2.234 -2.0 4.432 0.0 5.123 +0.2 8.654 +0.5 8.654 +0.8 8.654 +0.9 . . . .   Expected output  1.123 -4.0 2.234 -3.5 4.432 0.0 5.123 +0.2 8.654 +0.5 . . . . Value too great for base (error token is "09") Gauss law question with regard to this example I am really confused in Gauss law.  Why do E3 and E2 pointing up? and also E1 pointing down?  The lecture note said infer from symmetry and you will get the following but I dont really understand. Could anyone explain to me? I am new to gauss law. Finding $ \int^1_0 \frac{\ln(1+x)}{x}dx$ How do you update an Excel file (Data Refresh and update formulas) WITHOUT opening the file? I have an Excel file that want to update and save automatically with out having to open it or manually interact with.  Manually, I open the file up and hit data refresh which goes and does a SQL query and then hit F9 for the formulas to update and then I just close/save.    (I then would mail the file out to people using a perl script or use SAS JMP to run some numbers/charts and also mail them out.  Basically I need to script some things which require the XLS file to be updated.) I want to change my field from molecular biophysics to theoretical ecology. While they are basically required some same basic background (physics, math, programming), the rest is quite irrelevant. In my current draft of this part, about a half is about this the problem and the result of the work, another half is for my contribution and what I've learnt. Having said that, should I focus less on describing the work and leave space for the thing that will be useful for the next research?  Below is copy from .     What have you already done? What problems have you solved, or at least worked on? What independent projects have you been part of? What were your key contributions? What did you learn? What did you teach the world? How do your results compare to what was already known? What original ideas are you most proud of? Be specific, technical, credible, and confident (but not arrogant). Refer the reader to your web page for more details. Have a web page with more details: preprints, project reports, source code, videos, etc. Terence Tao, Analysis I, Ex. 5.5.2: Entry point needed Terence Tao, Analysis I, 3e, Exercise 5.5.2:     Let $E$ be a non-empty subset of $\mathbb{R}$, let $n \ge 1$ be an   integer, and let $L &lt; K$ be integers. Suppose that $K/n$ is an upper   bound for $E$, but that $L/n$ is not an upper bound for $E$. Without   using Theorem 5.5.9, show that there exists an integer $L &lt; m \le K$   such that $m/n$ is an upper bound for $E$, but that $(m-1)/n$ is not   an upper bound for $E$. (Hint: prove by contradiction, and use   induction. It may also help to draw a picture of the situation.)    does not do the trick for me, since I'm looking for the proof by contradiction, equipped only with the set of propositions and theorems covered so far.  What I'm actually looking for is an entry point to the proof, since I find it quite hard to negate the assumption.  My attempt is to induct over $n$. Assume I have been able to prove the statement for $n = 1$, is the following a valid negation of the assumption?  For all integers in the range $(L, K]$, at least one of the following statements holds:   $(m-1)/(n+1)$ is not an upper bound and $m/(n+1)$ is not an upper bound. $(m-1)/(n+1)$ is an upper bound and $m/(n+1)$ is not an upper bound. $(m-1)/(n+1)$ is an upper bound and $m/(n+1)$ is an upper bound.   If I were able to prove that there is an integer in the given range such that none of the above holds, am I done?       Theorem 5.5.9 (Existence of least upper bound). Let $E$ be a non-empty subset of $\mathbb{R}$. If $E$ has an upper bound, (i.e.,   $E$ has some upper bound $M$), then it must have exactly one least   upper bound.     I went through another loop considering  of Steve Kass, but I ended up wondering why the proof needs induction at all:  Assume for all integers $m$ where $L &lt; m \le K$ we have that $m/n$ and $(m-1)/n$ are upper bounds of $E$. Then $(m-1)/n = L/n$ is also an upper bound. But $L/n$ is no upper bound, by assumption. Assume $m/n$ and $(m-1)/n$ are no upper bounds. Then $m/n = K/n$ is also no upper bound. But $K/n$ is an upper bound, by assumption.   Hence, there is an integer in the range $(L, K]$ s.t. $m/n$ is an upper bound for $E$, and $(m-1)/n$ is not. I have a problem with derivation of some function. This is related to computing the Poincare Map of Logistic Population model with Periodic harvesting. This function is:  $\phi(t,x_0) = x_0 + \int_{0}^{t} f(s,\phi(s,x_0)) ds $,  where $\phi(t,x_0)$ is a function: $\mathbb{R}  \times \mathbb{R} \rightarrow \mathbb{R}$.  I'm trying to differentiate  equation of this function both sides  with respect to $x_{0}$. In book from this equation comes from the result of this differentiation is:  $\frac{\partial \phi}{\partial x_0} (t,x_0) = 1 + \int_0^{t} \frac{\partial f}{\partial x_0} (s, \phi(s,x_0)) \cdot \frac{\partial \phi}{\partial x_0} (s, x_0)ds$.  I can't understand expression under the integral. In this book it is explained that it is clear from chain rule.Could someone explain to me this transformation in easy way? I will be grateful for your help Best regards How can I explain why DRM cannot work? I am looking for the shortest comprehensive way to explain to people that are trying to use DRM as a technology to prevent users from using their data in some fashion deemed undesirable, why their solution cannot work by definition.  Ideally I'd like something that:   Covers why technically it is impossible to have people access local data, but only in such-and-such a way Imparts an understanding of why this is, to avoid follow-on "But what if" rebuttals Is intuitive enough and short enough that even a politician (j/k) could grasp it   When faced with this situation I try to be clear and concise, but I usually end up failing at least on one of these points. I'd really like to have a 'stock' answer that I can use in the future. How to use Launchctl for schedule application I try to work with Launchctl and have a question:  How can I set up an application to run in a few minutes using Launchctl? (for example, open the program MyApp.app with arguments "hello" "world" Every 10 minutes)  I know that it can easily be done by creating Launch Agent, I looking for a way to do it using Launchctl directly to programmatically. Is there an app that will notify me (in notifications center) if a process is using up a high percentage of CPU for a specified amount of time? The other day, I was sitting in a coffee shop working, when I looked down to find that 25% of my battery was left.   I looked at my Activity Monitor and saw that the time machine process was going at 90% for a while (as long as I was watching it).   Are there any apps that can notify me if a process is at a certain level for a certain amount of time? I'm having trouble understanding Cantor's diagonal argument.  Specifically, I do not understand how it proves that something is "uncountable".  My understanding of the argument is that it takes the following form (modified slightly from the  article, assuming base 2, where the numbers must be from the set $ \lbrace 0,1 \rbrace $):  \begin{align} s_1 &amp;= (\mathbf{0},1,0,\dots)\\ s_2 &amp;= (1,\mathbf{1},0,\dots)\\ s_3 &amp;= (0,0,\mathbf{1},\dots)\\ \vdots &amp;= (s_n \text{ continues}) \end{align}  In this case, the diagonal number is the bold diagonal numbers $(0, 1, 1)$, which when "flipped" is $(1,0,0)$, neither of which is $s_1$, $s_2$, or $s_3$.  My question, or misunderstanding, is: When there exists the possibility that more $s_n$ exist, as is the case in the example above, how does this "prove" anything?  For example:  \begin{align} s_0 &amp;= (1,0,0,\mathbf{0},\dots)\ \ \textrm{ (...the wikipedia flipped diagonal)}\\ s_1 &amp;= (\mathbf{0},1,0,\dots)\\ s_2 &amp;= (1,\mathbf{1},0,\dots)\\ s_3 &amp;= (0,0,\mathbf{1},\dots)\\ s_4 &amp;= (0,1,1,\mathbf{1},\dots)\\ s_4 &amp;= (1,0,0,\mathbf{1},\dots)\ \ \textrm{ (...alternate, flipped } s_4\textrm{)}\\ s_5 &amp;= (1,0,0,0,\dots)\\ s_6 &amp;= (1,0,0,1,\dots)\\ \vdots &amp;= (s_n \text{ continues}) \end{align}  In other words, as long as there is a $\dots \text{ continues}$ at the end, the very next number could be the "impossible diagonal number", with the caveat that it's not strictly identical to the "impossible diagonal number" as the wikipedia article defines it:     For each $m$ and $n$ let $s_{n,m}$ be the $m^{th}$ element of the $n^{th}$ sequence on the list; so for each $n$,      $$s_n = (s_{n,1}, s_{n,2}, s_{n,3}, s_{n,4}, \dots).$$      ...snip...      Otherwise, it would be possible by the above process to construct a sequence $s_0$ which would both be in $T$ (because it is a sequence of 0s and 1s which is by the definition of $T$ in $T$) and at the same time not in $T$ (because we can deliberately construct it not to be in the list). $T$, containing all such sequences, must contain $s_0$, which is just such a sequence. But since $s_0$ does not appear anywhere on the list, $T$ cannot contain $s_0$.      Therefore $T$ cannot be placed in one-to-one correspondence with the natural numbers. In other words, it is uncountable.   I'm not sure this definition is correct, because if we assume that $m = (1, \dots)$, then this definition says that "$s_n$ is equal to itself"&mdadsh;there is no "diagonalization" in this particular description of the argument, nor does it incorporate the "flipping" part of the argument, never mind the fact that we have very clearly constructed just such an impossible $T$ list above.  An attempt to correct the "diagonalization" and "flipping" problem:  $$s_n = (\lnot s_{m,m}, \lnot s_{m,m}, \dots) \quad \text{where $m$ is the element index and} \quad\begin{equation}\lnot s_{m,m} = \begin{cases}0 &amp; \mathrm{if\ } s_{m,m} = 1\\1 &amp; \mathrm{if\ } s_{m,m} = 0\end{cases}\end{equation}$$  This definition doesn't quite work either, as we immediately run in to problems with just $s_1 = (0),$ which is impossible because by definition $s_1$ must be $ = (1)$ if $s_1 = (0)$, which would also be impossible because...   Or more generally, with the revised definition there is a contradiction whenever $n = m$, which would seem to invalidate the revised formulation of the argument / proof.  Nothing about this argument / proof makes any sense to me, nor why it only applies to real numbers and makes them "uncountable". As near as I can tell it would seem to apply equal well to natural numbers, which are "countable".  What am I missing? Why does "start winword" work but just "winword" doesn't? Assume Microsoft Office is installed. Consider the following batch file:  REM the following line successfully launches Microsoft Word start winword  REM none of the following commands work to launch Microsoft Word winword winword.exe winword.com winword.bat winword.cmd winword.vbs winword.vbe winword.js winword.jse winword.wsf winword.wsh winword.msc   What is it about the "start" instruction that allows the launching of Microsoft Word using the name "winword"?  My curiosity stems from my interest in the mechanics of the "start" verb - I don't need suggestions on other ways to start Microsoft Office.  Please don't suggest that I add the Microsoft Office directory to my PATH environment variable - I know what that would do.    How is start finding "winword" when cmd cannot find it directly? Installing mysql-workbench in Ubuntu 19.04 The error looks like this:  Reading package lists... Done Building dependency tree        Reading state information... Done Package mysql-workbench is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package 'mysql-workbench' has no installation candidate   How do I install it? Offset a background image from the right using CSS What exactly happens when you browse a website in your browser? Is propagation of uncertainties linear?