How to make PHP input methods(get and post) safe by a simple code?
How can I prevent SQL injection in PHP?
Is there a way of finding a formula for $\sum\limits_{k=1}^n k^k$? Maybe I'm missing something really obvious, but I've looked around a bit on the Internet and I haven't been able to find anything.  So, what I'm looking for is a formula in closed form to generate the sequence $1,5,32,288,3413,\dots$ I'm looking for a word that can describe a person who does nice things for other people (e.g holding the door open, carrying someone's things) but only for self gain; this person only does nice things to make themselves look good in the eyes of others, but doesn't actually care about the well-being of the people they're helping. Roots of polynomials in field of prime characteristic p Let $F$ be a field of characteristic $p$, and let $\alpha \in F$. Let $f \in \mathbb{Z}_p[x]$ be such that $f(\alpha) = 0$. Apparently, we have $f(\alpha^p) = 0$. This was mentioned but not proved in my lectures. Can someone explain why please?  Thanks. "There are currently N bounties, worth X reputation" dynamic ad and the new sidebar width You've probably seen this sidebar ad on one or more -enabled Stack Exchange sites over the years:    The image is dynamically generated from a non-officially SE app that uses the Stack Exchange API to fetch the bounties from a given site.  As far as I understand, the rendered image automatically scales to the allotted ad space - when the sidebar ads were 220x250, it would render in the sidebar as a 220x250 image while still looking quite oversized in the  meta (as it does right here).  With the new 2016 campaign starting, can we test whether this awesome dynamic ad works with the new sidebar width? I'm hoping someone could check my work. I'm trying to simplify the equation for $x$. $$(\frac{x}{a})^{3.2} + (\frac{y}{b})^{3.2} = 1$$ $$\frac{a}{b} = \frac{174.1}{86}$$ Thus I began by substituting $a$ with: $$a = \frac{174.1}{86}b$$ $$((\frac{86}{174.1})(\frac{x}{b}))^{3.2} + (\frac{y}{b})^{3.2} = 1$$ $$((\frac{86}{174.1})(\frac{x}{b}))^{3.2} = 1 - (\frac{y}{b})^{3.2}$$ $$(\frac{x}{b})^{3.2} = \frac{(1 - (\frac{y}{b})^{3.2})(174.1)^{3.2}}{(86)^{3.2}}$$ $$x^{3.2} = \frac{(1 - (\frac{y}{b})^{3.2})(174.1)^{3.2}(b)^{3.2}}{(86)^{3.2}}$$ $$x^{3.2} = \frac{(1 - (\frac{y}{b})^{3.2})((174.1)(b))^{3.2}}{(86)^{3.2}}$$ $$x^{\frac{16}{5}} = \frac{(1 - (\frac{y}{b})^{3.2})((174.1)(b))^{3.2}}{(86)^{3.2}}$$ $$x = [\frac{(1 - (\frac{y}{b})^{3.2})((174.1)(b))^{3.2}}{(86)^{3.2}}]^{\frac{5}{16}}$$ Is my work correct, or am I completely off the board? Generate random numbers uniformly over an entire range Using find with grep, one can locate files that match a pattern:  # find | grep error ./solr-modifiedSolr4/SolrPhpClient/phpdocs/errors.html ./error_log ./includes/classes/error_log   However, using find alone the first file is not found:  # find . -name error* ./error_log ./includes/classes/error_log   Why doesn't find locate the errors.html file when not used with grep? How is find used to show this file as well? Why we won't extract heat from air temperature? How should I add users non-interactively? I have a set of users I need to add to a new system as part of a BASH script that preps my server. How can I non-interactively add the user, create their home directory, set the group, and enter a default password?  For example, if I needed to add the following users, how would I go about that?  user: node password: spoon group: ultraMegaPermissions  user:serve password: spoot group: sortaNotMega  user:watcher password: spoogle group: notMega I know that there are questions asking like "intersection of a infinite collection of sets" and I can understand that the answer for that one is a null set, but I got a question here, in which all sets are finite and nonempty. Please take a look at the pic below.  It's a True/False question.  What I'm confused about is that the "infinity" sign in the interception. Since all sets are finite, does it mean that there are many sets in the chain are the same? (because the symbol used is for subsets not for proper subsets). Please give me some hints how I should think about this question.  Thank you How to study/prepare for the Salesforce Developer Certification I am fairly new to Force.com development (less than a year). I did not learn it from the ground up. So I think it will be good to study for the developer exam to strengthen my basics and improve my overall knowledge of Force.com + it will be great to have this certification.  Now it's surprising that there is not a lot of great information on the web about how to go about obtaining this certification. Most other major certifications have dedicated study guide books available but there are few for Force.com and I don't think any of them are official.   The official page has little information. The Study guide gives a broad description of the topics in the test.   I see a lot of the esteemed members are here certified developers. I think if you guys could give us a little information, hints/tips and some advice on how to prepare for this exam, it will really be of great help. Also is DEV401 required/helpful?  Also if we could get recommendations for great resources(books, online training etc) and practice tests it will be awesome. Fixing scrolling in nano running in tmux in mate-terminal The problem:   I open a terminal (in Linux Mint, so mate-terminal) zsh is the shell Then I run tmux Edit a file with nano Scroll up and down that file with the cursor Issue: When scrolling down in nano, only the bottom half of the terminal window gets refreshed Issue: When scrolling up in nano, only the top half of the terminal windo gets refreshed   The complete nano view of file does not get refreshed in my terminal window when scrolling. Any tips?  Edit: my .tmux.conf  It seems that this line specifically is the culprit (as commenting it out fixes the problem):  set -g default-terminal "xterm-256color"   I'm pretty sure I added that line because I have issues even running nano during an SSH session.  Here is the full file:  set-option -g default-shell /bin/zsh  # Make sure tmux knows we're using 256 colours, for # correct colourised output set -g default-terminal "xterm-256color"  # The following were marked as "unknown", so # I do know what I'm doing wrong. #set -g mode-mouse on #setw -g mouse-select-window on #setw -g mouse-select-pane on  # Attempting to stop "alert" sound upon startup # but none of these are working... set-option bell-on-alert off set-option bell-action none set-option visual-bell off Why is Ubuntu using so much memory? I have just turned on my PC and have two applications running; Thunderbird and Firefox. Whatever else is running is part of Ubuntu's feature set (as well as a few indicators).  This has been ongoing for weeks, so I'm not sure if it's normal behaviour or not.  Right now, my memory usage indicator says that Ubuntu is using 41% of my 6GB of RAM. I haven't even opened Gimp or my other day-to-day things. I'll be buying another 6GB of RAM, this week, so that I don't run out when using Gimp or Openshot, for example.  An overview of my running applications shows that Nautilus is using the most, yet it isn't even open. This seems a little excessive, or am I missing something? If $A|B$ and $B|A$ then prove $A=\pm B$ If $A|B$ and $B|A$ then prove $A=\pm B$   So far I have $A|B \iff AX=B$ and $B|A \iff BY=A$ with $X,Y \in \mathbb{Z}$  Not sure how to finish, any help. HP Easy Scan - "HP Scanner 3" will damage your computer What would be the Slater's determinant representation for an excited state? Setup  Introducing this spinorbital notation:  \begin{align} \Psi_1=\chi_{(r1)}\alpha_{(\omega1)}  = 1 \\ \Psi_1=\chi_{(r1)}\beta_{(\omega1)}  = \bar{1} \end{align}  and the Slater's determinant, for a system of two electrons, is:  \begin{align} |\Psi\rangle = \frac{1}{\sqrt{2}} \Big|  \begin{array}{cc} 1 &amp; \bar{1}  \\ 2 &amp; \bar{2}  \\ \end{array}  \Big| = \frac{|1\bar{2}\rangle-|\bar{1}2\rangle}{\sqrt2} \end{align}  Question  Based on the example, what would be the Slater's determinant representation for an excited state like $\Psi_a^r$ (i.e. with parallel spins like: $|\bar{1}\bar{2}\rangle$) and $\Psi_{ab}^{rs}$ (feel free to use any number) ? Power series of a function I am wondering if there are any functions $f(x)$ such that it cannot be expressed as a power series of $x$? This might turn out to be a silly question, but I can't think of one at the moment.   Thanks! Fibonacci combinatorial identity: $F_{2n} = {n \choose 0} F_0 + {n\choose 1} F_1 + ... {n\choose n} F_n$ Can someone explain how to prove the following identity involving Fibonacci sequence  $F_n$  $F_{2n} = {n \choose 0} F_0 + {n\choose 1} F_1 + ... {n\choose n} F_n$ ? Compound possessives and yours Why can't we see the selected reasons when there are pending close votes for a question? When users vote to close a question, the original poster can't see the selected reason why until after the question is already closed.  If they could see this information, they might be able to edit the question to make it more acceptable and averting the need to close it.  For example, the owner of this  cannot see the reason why his question is being voted to close: