Exception in thread "main" java.lang.NullPointerException in LU Decomposition Method
What is a NullPointerException, and how do I fix it?
How should a GM deal with "standing orders?" Difference between StringBuilder and StringBuffer What is the main difference between StringBuffer and StringBuilder? Is there any performance issues when deciding on any one of these? Prove $\frac{a+b+c}{abc} \leq \frac{1}{a^2} + \frac{1}{b^2} + \frac{1}{c^2}$. So I have to prove $$ \frac{a+b+c}{abc} \leq \frac{1}{a^2} + \frac{1}{b^2} + \frac{1}{c^2}.$$  I rearranged it   $$ a^2bc + ab^2c + abc^2 \leq b^2c^2 + a^2c^2 + a^2b^2 .$$  My idea from there is somehow using the AM-GM inequality. Not sure how though. Any ideas?  Thanks Is there a cross-browser onload event when clicking the back button? Dumbed-down explanation how scientists know the number of atoms in the universe? It is often quoted that the number of atoms in the universe is 10$^{70}$ or 10$^{80}$.  How do scientists determine this number?   And how accurate is it (how strong is the supporting evidences for it)?  Is it more likely (logically >50% chance) that the numbers are right, or is it more likely that the numbers are wrong? Some compound words are written without hyphens (nonaggression, nonbeliever), some with hyphens (well-intentioned), and others with spaces (post office).  Is there a rule or good guide as to which option should be used? Unable to locate package kubuntu-plasma5-desktop on 14.04 I am attempting to install kubuntu-plasma5-desktop on Kubuntu 14.04 amd64, following    sudo apt-add-repository ppa:neon/kf5 sudo apt update sudo apt install project-neon5-session project-neon5-utils project-neon5-konsole  sudo apt-add-repository ppa:kubuntu-ppa/next sudo apt-add-repository ppa:ci-train-ppa-service/landing-005 sudo apt update sudo apt install kubuntu-plasma5-desktop   Unable to locate package kubuntu-plasma5-desktop  How can I fix this error? Additional Drivers for Ubuntu 17.10 The Additional Drivers settings interface is no longer available in Ubuntu 17.10  How can I install proprietary drivers in Ubuntu 17.10?  I need drivers for Wifi &amp; Bluetooth (BCM43142) and Intel Graphics.  The earlier Additional Drivers program showed a package named jockey but it no longer seem to exist in repositories. Why won't vertical-align: middle work?  And yet, vertical-align: top does work.   span{   vertical-align: middle; } &lt;div&gt;   &lt;img src="https://via.placeholder.com/30" alt="small img" /&gt;   &lt;span&gt;Doesn't work.&lt;/span&gt; &lt;/div&gt; Clicking on the rep league lines that read like &quot;top 2% this quarter&quot; returns a 404 page. Example in point:  This report is split off as per request of Adam Lear from Bolding with ** isn't working properly Have a look at   One of the bolds works, and the other one just turns up as ** in the actual post.  This is the string that isn't working: **x**ml n**ib**  Which renders as: xml nib In the 3d viewport I am using a border region to only render things inside the selected region. I did this with CtrlB. I cannot get rid of the region. How can I make the border disappear? Is the integral $\int_0^\infty \frac{\mathrm{d} x}{(1+x^2)(1+x^a)}$ equal for all $a \neq 0$? Let $a$ be a non-zero real number. Is it true that the value of $$\int\limits_0^\infty \frac{\mathrm{d} x}{(1+x^2)(1+x^a)}$$  is independent on $a$? How do I fix a "Unknown configuration key `foreign-architecture' found in your `dpkg' configuration files." error? $AB-BA$ is a nilpotent matrix if it commutes with $A$ I saw this in a  and am putting it here for posterity.  Problem: Let $A$ and $B$ by square matrices and set $C=AB-BA$. If $AC=CA$, prove $C$ is nilpotent. Georeferencing vector PDF/SVG/DXF linework using QGIS? I want to  create a small web application to visualize election results on a per poll site basis for my city. The result is going to be very similar to what has been done for Berlin . Hopefully this helps in understanding what I'm going for.  The election raw data on the scale I need is published and I know how to visualize this on the grounds of a shapefile with separate polygons lining out the election districts. My problem is - as you could probably guess - that something like this doesn't already exist.  What actually is published though, is a PDF file lining out the borders of the districts I'm interested in:   I'm not keen on redrawing the linework myself, so I'm looking for a way to make a shapefile out of this. Luckily, the PDf includes the linework as separate vector objects, I extracted these into a SVG file:   I already tried converting the SVG to a DXF and importing it into qgis 2.0.1. This actually works, but (as expected) places the vectors in the atlantic ocean and I can't find a way to edit it and fix this.  What can I do now to georeference these vectors with open source tools and finally produce a shapefile? Automatically set description list `labelwidth` based on widest label? How do I create a description list where the item text is automatically indented to the width of the widest label?  This is the same question as  but I would like the width of the widest label to be automatically calculated.  For example, I'd like the following output:    to be produced by the following input:  \documentclass{article} \usepackage{calc} \usepackage{enumitem} \usepackage{lipsum} \usepackage[margin=1em,papersize={4in,2.2in}]{geometry}  \newenvironment{mydescription}{%   \begin{description}[     leftmargin=!,     labelwidth=\magicgoeshere,     ]% }{%   \end{description}% }  \newcommand{\text}{long long long long long long long long long long   long long long long long long long long long long long long long   long long long long long long long text}  \begin{document} \begin{mydescription} \item[The longest label] text \item[Short] \text \end{mydescription} \hrule \begin{mydescription} \item[Medium label] text \item[Short] \text \end{mydescription} \end{document} To prove $\left|\frac{p_n(z)}{q_m(z)}\right|\leq \frac{M}{|z|^{m-n}}$ for some $M>0$ How do I find out a name of class that created an instance of an object in Python if the function I am doing this from is the base class of which the class of the instance has been derived?  Was thinking maybe  might have helped me out here, but it doesn't seem to give me what I want. And short of parsing the __class__ member, I'm not sure how to get at this information. My opponent casts , which resolves, then he attacks with his creatures.  In my hand, I have a creature card with Flash. If I summon this creature before the declare blockers step, will it be affected by Predatory Rampage's blocking requirement?