Error "Non static method cannot be referenced from a static context"
What is the reason behind "non-static method cannot be referenced from a static context"?
su vs sudo -s vs sudo -i vs sudo bash What is the difference between the following commands:  su sudo -s sudo -i sudo bash   I know for su I need to know the root password, and for sudo I have to be in the sudoers file, but once executed what is difference?  I know there is a difference between su and sudo -s because my home directory is /root after I execute su, but my home directory is still /home/myname after sudo -s. But I suspect this is just a symptom of an underlying difference that I'm missing. Exporting Data From Salesforce - REST or SOAP? Why doesn't Zorn's lemma apply to $[0,1)$? I've already taken my calculus sequence and I'm interested in brushing up and staying sharp on the basics. So far, my calculus background is limited to single-variable calculus, which I applied in my physics sequence and engineering statistics. I learned a little bit of vector math in physics as well, but I'm not strong in it. My mathematical strengths lie in the discrete mathematics.  I'm particularly interested in studying for my IEEE Certified Software Development Associate exam - 10% of the exam is mathematics (calculus, differential equations, and statistics). Calculus is one of the mathematics knowledge areas that a software engineer should be competent in, so I'm looking for not only solidifying the courses that I've already taken, but moving forward with slightly more advanced topics, at an undergraduate mathematics level.  I'm currently using the textbook from my calculus sequence, but I'm interested to know what books other people used to learn calculus and if the book is potentially worth checking out.  What books are available to help me? $\|h(x)-h(y)\|\geq 3\|x-y\|$ prove that image of open is open Challenges with Key with Gaps? I've heard that i can travel to the US any time before my tourist visa expiry.  Is that true?  (please advise) What will I miss out on if I play Diablo 3 without Reaper of Souls? I own the base game of Diablo 3.  I didn't really like the "post-Inferno" content of the game, so I stopped playing shortly after I curb-stomped the final boss for the n-th time.    I understand now that a lot of things have changed in the base game.  There's also an expansion.  I don't plan to purchase the expansion, but some of these changes sound like they could make the game more fun for me.  I can guess that probably the new character and act are expansion-only content.  I know I'm probably , but if I go back and play now, what else will I be missing out on if I don't have the expansion? Different results for integration using Mathematica and MATLAB Sequential Update of Bayesian I am currently reading Murphy's ML: A Probabilistic Perspective. In CH 3 he explains that a batch update of the posterior is equivalent to a sequential update of the posterior, and I am trying to understand this in the context of his example.  Suppose $D_a$ and $D_b$ are two data sets and $\theta$ is the parameter to our model. We are trying to update the posterior $P(\theta \mid D_a, D_b)$. In a sequential update, he states that, $$ (1) \ \ \ \ \ \ \ \  P(\theta \mid D_{a}, D_{b}) \propto P(D_b \mid \theta) P(\theta \mid D_a) $$ However, I am slightly confused as to how he got this mathematically. Conceptually, I understand that he is saying the posterior $P(\theta \mid D_a)$ is now a prior used to update the new posterior, which includes the new data $D_b$, and is multiplying this prior with the likelihood $P(D_b \mid \theta)$. Expanding the last statement out, I have, $$  P(D_b \mid \theta) P(\theta \mid D_a) = P(D_b \mid \theta) P(D_a \mid \theta) P(\theta) $$  but are we allowed to say $P(D_a \mid \theta) P(D_b \mid \theta) = P(D_a, D_b \mid \theta)$ in order to make the connection in (1)? How much money did Harry Potter have? So, we know Harry . By descriptions from the books, it looks like he had enough money to spend during his school years with plenty to spare for later life.  Is there an estimate on how much money he had? How much would that be in muggle money? Was he extremely rich?  I'm thinking here that he could have received more than just an inheritance. For example, anonymous supporters could have given him money through the bank while he was a baby, or when he was about to go to Hogwarts, and he wouldn't have known (not even Dumbledore would have known). I compiled the following file (through MiKTeX which I have just updated all files), and I do not get the junk.pdf file inserted.  \documentclass{report} \usepackage{pdfpages} \begin{document} qwe \includepdf[pages=-]{./junk.pdf} \end{document}   The .log and junk.pdf file are there: ;   OK, yes it works with pdflatex, but I have to use latex->dvips->ps2pdf because of other constraints insertion of EPS figures). Beside, I do not know how to use the suggested lastpage option.  Using \includepdf[nup=2x2,frame,pages={1-13}]{./junk.pdf} I do correctly get 5 pages which should have included junk.pdf, but I get blank pages with a black dot in the center. In unix/linux, any number of consecutive forwardslashes in a path is generally equivalent to a single forwardslash. eg.  $ cd /home/shum $ pwd /home/shum $ cd /home//shum $ pwd /home/shum $ cd /home///shum $ pwd /home/shum   Yet for some reason two forwardslashes at the beginning of an absolute path is treated specially. eg.  $ cd ////home $ pwd /home $ cd /// $ pwd / $ cd // $ pwd // $ cd home//shum $ pwd //home/shum   Any other number of consecutive forwardslashes anywhere else in a patch gets truncated, but two at the beginning will remain, even if you then navigate around the filesystem relative to it.  Why is this? Is there any difference between /... and //... ? Hyperlinks are not visible in the generated PDF CV Sometimes when I am running a development version of Ubuntu, the Software Updater will tell me that a partial upgrade is needed when I check for updates.  What is a partial upgrade, and why are they necessary? Sometimes users run into problems when doing them, so when should I run a partial upgrade, if ever? Elementary central binomial coefficient estimates How can I prove that if $G$ is an Abelian group with elements $a$ and $b$ with orders $m$ and $n$, respectively, then $G$ contains an element whose order is the least common multiple of $m$ and $n$?  It's an exercise from Hungerford's book, but it's not homework. I could not solve it when I take the course on groups and I think it should be easy. There is a hint that says to first prove when $m$ and $n$ are coprimes. I did this part. But I have no idea how to solve the general case.  Thanks. Add a message when posting to old questions with more than N answers Are all eigenvectors, of any matrix, always orthogonal? Why does cancellation of dots $\frac{\partial \dot{\mathbf{r}}_i}{\partial \dot{q}_j} = \frac{\partial \mathbf{r}_i}{\partial q_j}$ work?