expects parameter 1 to be mysqli_result, boolean given
mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc... expects parameter 1 to be resource
Accessing my Windows 7 files from my Ubuntu account Is there a test to determine whether solder is leaded or lead-free? Perhaps conductivity/resistance? "Can't find Project or Library" for standard VBA functions How does the Schengen 90/180 rule work? I have searched the web a lot and could not find an answer that fits my situation. Here are two links that are quite contradictory:       My situation:  I've visited Portugal in December 2012 for 29 days on a Schengen visa valid from December 1st, 2012 to February 1st, 2013 for research purposes (I am a Ph.D. student). I want to visit Sweden from February 10th, 2013 to May 10th, 2013 (89 days). I have applied for a Schengen visa again (for research). How will the 90/180 rule work in my situation? Suppose someone from "Harry's world" married a Muggle, and they want to escort their child. Can the Muggle parent get through to the Hogwarts platform? Is it possible to switch from one area of graduate study to another in US universities? For example, suppose someone has enrolled in a computer science phd program. Can he switch over to math(or physics) phd program in the same school later?(or say from applied mathematics to pure mathematics?)  What are the steps for doing for doing that? If $a\neq 1$, find $(a+1)(a^2+1)(a^4+1)\ldots(a^{2^n}+1)$. If $a\neq 1$, find $$(a+1)(a^2+1)(a^4+1)\ldots(a^{2^n}+1)$$   Or i.e.     If $a\neq 1$, find $\prod_{i=0}^n(a^{2^i}+1)$.   It really does seem like $$(a+1)(a^2+1)(a^4+1)\ldots(a^{2^n}+1)=a^{2^n+2^{n-1}+\ldots+2+1}+a^{2^n+2^{n-1}+\ldots+2+1-1}+a^{2^n+2^{n-1}+\ldots+2+1-2}+\ldots+a^2+a+1$$  Or i.e. $$\prod_{i=0}^n(a^{2^i}+1)=\sum_{i=0}^{2^n+2^{n-1}+\ldots+2+1}a^i$$  Is there an interesting proof of this? I'd appreciate any help. Tags on badge question list I'm trying to get the Weed-Eater hat on Stack Overflow. To do so, I'm looking at the list of questions . The problem is, no tags show up there, and so it's rather difficult to see which ones I have a shot at. Any chance of showing the tags on this page?  I realize that getting this before Winter Bash is over would be difficult, but it would be good to keep such things in mind for the future. What free Remote Desktop (server) solutions are there? I know Ubuntu comes with a "Remote Desktop" option that appears to be a straightforward VNC server, and I'm trying to understand the alternatives. Here are the possibilities I've heard about so far:   VNC  VNC + SSH Tunnelling NX Server, free edition FreeNX NeatX X2Go X11 Forwarding over SSH xrdp    I'm coming at this from a Windows user's perspective: To the best of my experience, RDP (aka Terminal Services) is a reasonably secure (barring mitm/server spoofing), efficient desktop sharing protocol with well-supported clients, that can be exposed to the internet when necessary without major fears of intrusion. To the best of my knowledge straight VNC is none of those things, which is where I get confused - why wouldn't a better desktop sharing technology be developed or used in the open-source world? I know VNC can be wrapped with SSH, but that seems beyond the reach of a casual user. X11 forwarding over SSH may be more or less efficient, I have no idea, but is definitely even more complicated, and doesn't (as far as I know) give you access to already-running stuff (no desktop sharing as such, just remote application running).  So, I'd like any feedback/preferences amongst these or any other "Free" desktop sharing options, using these criteria and/or any others:   Security (esp. for access across internet) Efficiency (bandwidth usage, responsiveness, etc) Free-ness, as in Speech (not sure where RDP or FreeNX lie for this) Free-ness, as in Beer (are there any commercial solutions with usable dependable free offerings?) Ease of use (server and client side) Cross-OS Client availability Cross-OS Server availability Support for independent sessions and shared (and/or "Console") sessions Ongoing support/maintenance/development   Thanks! The question is raised from the viewpoint of a foreign language learner.  -ed is known to be added to a verb to mean past tense or past participle, but some phrases like four-legged animals, winged birds, are in the form of noun+-ed, why is it so? What is the logic behind such a structure? Difference between standard beta and unstandard beta distributions? What is the difference between standard beta and unstandard beta distributions? How to understand in an article if it is not described if it is standard or not? Calculating half derivative of $x$ using Cauchy's repeated integral formula As far as I know, Cauchy's repeated integral formula is defined as: $$(I^nf)(t)=\frac{1}{\Gamma(n)}\int_a^x (x-t)^{n-1}\space f(t)\space\space dt,\space\space n\notin Z_{\le 0}$$  I know that Gamma function is not defined for negative integers and $0$. I also know that differentiation and integration are inverse operators so I thought of finding $\frac{-1}{2}$th antiderivative of $f(x)=x$ so that I can find the half derivative of $x$. However it seems that it does not work. What is the problem with this? Am I missing something or is it not possible? I know some other ways of finding half derivative of $x$, so what I am asking is the problem about what I tried.  My attempt: $$\frac{1}{\Gamma\left(-\frac{1}{2}\right)} \int^x_0(x-t)^{-\frac{3}{2}}\space t\space dt=\frac{x}{2\sqrt{\pi}}\int^0_x u^{-\frac{3}{2}}\space (x-u)\space du$$  This definite integral is divergent and so I cannot get to a result. If $\mathfrak p \subset R$ is a prime ideal, prove that for every nilpotent $r \in R$ it follows that $r \in \mathfrak p$.   The only hint that my tutor gave me was to use induction. Can someone explain what he means by this?  Thanks for the help! For each positive even integer $n$, set   $$P_n = \displaystyle {{n} \choose {\frac{n}{2}}}\frac{1}{2^n}.$$  Show that $\displaystyle \lim_{n \to \infty} P_n$ exists and determine its value.   Here's what I have so far: each $P_n$ can be thought of as the probability of tossing a fair coin $n$ times, and obtaining exactly $\frac{n}{2}$ heads. My expectation is that $P_n \to 1$, since in any large trial, one would expect to record just about as many heads as tails. But I'm not sure how to mathematically justify this hunch.  Hints or solutions are greatly appreciated. I gave Google my phone number to verify it, not knowing that it would change it, and now my phone number is completely different? What have I done, and how do I unverify it and change my phone number back? A better answer was posted long after accepting another. Should I accept the new one? Why does `\texttt` repeat and shrink my equation? When I use \texttt with the caret symbol in an amsmath equation environment, I get a very weird result. Specifically, the text repeats itself four times while shrinking.  MWE:  \documentclass{article} \usepackage{amsmath}  \begin{document}  \begin{equation*}     \texttt{y^o} \end{equation*}  \end{document}   Compiling this document with pdflatex produces the following result:    The same result occurs even if I remove the o character. To fix it I could modify the offending line to \texttt{y$^o$}, but why is this repeating happening in the first place? For whatever reason, we do no longer need to be root (or using sudo) to run /sbin/shutdown, /sbin/reboot etc.  This seems to be because those executables are now symlinks to /bin/systemctl which handles everything as normal user.  However, what if I want shutdown and reboot to require root authentication again? How can I achieve this? How to work the BibTeX? I have searched the tutorials but have not been successful in understand them. The tutorials always mensionam concepts that I do not know. I would like to understand the basics of BibTeX.  By basics I mean:   How do I install BiBTeX? How to build a file in bib? For this question assume that I already have the bibtex format each reference provided by databases like MathSciNet. See observation 1 below. What I write commands in the file format. Tex to call call the format file bib? How to exploit the format of the bibliography that comes out in PDF? The commands are made in the preamble of the file. Arquifo bib or format. Tex? What must be the BiBTeX with biblatex? Is there any tutorial (in pdf or video) that teaches step by step how to operate BiBTeX?   Observation 1 I already have the bibtex format each reference provided by databases like MathSciNet:   @article {MR2373353,  AUTHOR = {Avila, Artur and Lyubich, Mikhail},  TITLE = {Hausdorff dimension and conformal measures of {F}eigenbaum {J}ulia sets},  JOURNAL = {J. Amer. Math. Soc.},  FJOURNAL = {Journal of the American Mathematical Society},  VOLUME = {21},  YEAR = {2008}, NUMBER = {2},  PAGES = {305--363},  ISSN = {0894-0347},  MRCLASS = {37F35 (37F10 37F25)},  MRNUMBER = {2373353 (2009i:37112)},  MRREVIEWER = {Feliks Przytycki},  DOI = {10.1090/S0894-0347-07-00583-8},  URL = {http://dx.doi.org/10.1090/S0894-0347-07-00583-8}, } Whenever I create a document in Microsoft Word, it complains about a lot of my sentences being in passive voice. But, when I read that sentence aloud, it sounds fine to me. I am not sure if it is just me and will a statement in passive voice sound strange to a native speaker?  So, my question is, is it considered bad form to use passive voice generally? Or in some specific cases like written communications only?  Edit: If it is ok to use passive voice, then why does MS-Word complain?