At or in? What's the difference? Which is more preferable? Which one is correct and what's the difference?  What would you say if someone asked you what you were doing yesterday:     I was shopping at a convenience store yesterday.       I was shopping in a convenience store yesterday.      I was doing the shopping at a convenience store yesterday.      I was doing the shopping in a convenience store yesterday.   or what you did yesterday:     I did the shopping at a convenience store yesterday.       I did the shopping in a convenience store yesterday.
Should I say "She is in the park" or "She is at the park"? I am really confused.  Which preposition is correct?     She is in/at the park.   They are in/at the park.   I am in/at the park.   Should I use in or at in these sentences?
Can anyone point me to a reference (preferably either something online or something a small liberal arts school would be likely to have in its library) that goes through a derivation of the minimum uncertainty wavefunction in more detail than in the Griffiths?  Edit I've moved the second part of my original question to a separate post: Undefined reference to static class member I have the loop tools addon enabled and when I click the circle button with these verts selected, it just disappears. Why is that?  You can see the selected options in the bottom screenshot. It is worth noting that all the verts are flat on the x plane. Locking in X or not does not change the effect.   When I use the to sphere operator it squishes the verts on Z and stretches super wide on Y, not making a cirlce.    EDIT:  here is the blend When should I make explicit use of the `this` pointer? When "Questions that may already have your answer" (similar questions) appear as a right column, it overflows and overlaps the footer.  (shown in the figure)        This happens on all SE network sites on which I have asked questions.  Also this happens to other columns also like "How to Format". Greets  This is exercise 15.d chapter 3 of Stein &amp; Shakarchi's "Complex Analysis", they hint: "Use the maximum modulus principle", but I didn't see how to do the exercise with this hint rightaway, instead I knew how to do it with the Casorati-Weiestrass Theorem, here is my answer:  Define $g(z)=f(1/z)$ for $z\neq{0}$,then by the hypothesis we must have that for any $\epsilon&gt;0$ $g(D_{\epsilon&gt;0}(0)-\{0\})$ is not dense in $\mathbb{C}$, then the singularity at $0$ of $g$ is not essential, this implies $f$ must be a polynomial, but if $f$ is a non-constant polynomial, it is easy to see that its real part must be unbounded, so $f$ must be constant.  I would like to know an answer with the the maximum modulus principle.  Thanks How to perform hard / cold reboot of iPhone or iPad? I understand that when I press and release the power button on the top of my iPhone or iPad, it stays on but turns off the screen.  Whereas if I press and hold the power button, a "slide to turn off" control appears on the screen.  Sliding this, as I was told, does turn the unit off, but it does so by suspending the RAM to disk (flash memory, actually.) So, when turning on the iPhone or iPad, it isn't so much rebooting the OS as it is resuming it from flash storage.  How to force the OS to completely reboot on these devices? Can I use an inner tube that's too narrow for the tyre? I recently got a puncture and when I went to replace the inner tube I discovered that I'd bought the wrong size tube. My tyre is 700 x 40c, the tube is 700 x 28-35c.  What is likely to happen if I use this tube? Will the tube explode when I attempt to inflate it? I have just updated (through Software Update) to Ubuntu 16.04 LTS from 15.10. There are random instances of screen flickering throughout usage. After noticing this issue, I installed Compiz Config Settings Manager, selecting Force fulls screen redraws (buffer swap) on repaint, which did nothing.   Is there any way this could be related to compiz settings or is this another issue?    EDIT: not fixed after clean install, upgrade to kernel 4.5.2, however screen flickering is reduced, it is every now and then (10 minutes apart). I will see if upgrading to kernel 4.6.0-994-generic will fix this.     EDIT: fixed as of kernel 4.6.2 generic,  currently running 4.7.2 without any issues. Would a backpack or cargo rack be better for commuting? Right now I use a backpack to hold all of my supplies including spare tubes, pump, patch kits, tools, my change of clothes for work, etc.  This is the backpack I use:    It's about as comfortable as a backpack can get without getting into the hiking backpacks with frames. Altogether I would say it weighs no more than 10 lbs max. The muscles in my back get slightly irritated during my commute.  Would it be more comfortable to use a rear cargo rack on my bike instead? Will adding more weight to the bike change how the bike rides and feels?  EDIT: After doing some research I came across  that explains the different methods of carrying your gear on commutes and how it affects your body. It's worth a look.  EDIT #2: Having tried both for a couple of weeks now, I can say that (for me personally) the backpack is the better way to go given the relatively light weight I have to carry.  If you do use a backpack, make sure that the straps are tightened enough so that it's positioned higher up on your back and to the point to where there is little to no movement on your back. This makes a world of difference when it comes to comfort. Can 'AMD-only' RAM really be restricted to AMD chipsets, and if so, why? Is my processor 64 or 32 bit? Some mesh-edges in object-mode aren't displayed So I have been extruding a cube to make a low poly banana and when I go from edit to object mode half the edges don't appear as well as half is dark.      I tried looking for an solution couldn't find one and its making me feel like I am doing something wrong so I decided to come here. Does the force of kinetic friction increase with the relative speed of the objects involved? If not, why not? Does deleting iCloud photos affect them on devices? Using Integration By Parts results in 0 = 1 I've run into a strange situation while trying to apply Integration By Parts, and I can't seem to come up with an explanation.  I start with the following equation:  $$\int \frac{1}{f} \frac{df}{dx} dx$$  I let:  $$u = \frac{1}{f} \text{ and } dv = \frac{df}{dx} dx$$  Then I find:  $$du = -\frac{1}{f^2} \frac{df}{dx} dx \text{ and } v = f$$  I can then substitute into the usual IBP formula:  $$\int udv = uv - \int v du$$  $$\int \frac{1}{f} \frac{df}{dx} dx = \frac{1}{f} f - \int f \left(-\frac{1}{f^2} \frac{df}{dx}\right) dx$$  $$\int \frac{1}{f} \frac{df}{dx} dx = 1 + \int \frac{1}{f} \frac{df}{dx} dx$$  Then subtracting the integral from both sides, I've now shown that:  $$0 = 1$$  Obviously there must be a problem in my derivation here...  What wrong assumption have I made, or what error have I made?  I'm baffled. It seems like I'm doing something wrong when using foreach variables to indicate node numbers. The two foreach loops are anchoring the paths to the east of each node. Why does this happen?    \documentclass{article}  \usepackage{tikz} \usetikzlibrary{backgrounds,fit,patterns,decorations.pathreplacing,calc}  \makeatletter \tikzset{   labelnode/.style={draw=none, fill=none, black},   latentnode/.style={draw, minimum width=5mm, shape=circle, ultra thick, black},   dagconn/.style={arrows=-&gt;, black, thick}, } \makeatother  \begin{document} \begin{tikzpicture}[scale=1]  \pgfmathsetmacro{\colgap}{1.6}  \pgfmathsetmacro{\rowgap}{1.3}   \node[labelnode] (x1) at (\colgap*0,\rowgap*1) {$X_1$};  \node[labelnode] (x2) at (\colgap*1,\rowgap*1) {$X_2$};  \node[labelnode] (x3) at (\colgap*2,\rowgap*1) {$X_3$};   \node[latentnode,blue] (x4) at (\colgap*0,\rowgap*0) {$X_4$};  \node[latentnode,red] (x5) at (\colgap*1,\rowgap*0) {$X_5$};  \node[labelnode] (x6) at (\colgap*2,\rowgap*0) {$X_6$};   \foreach \c in {1,...,2} {    \foreach \r in {1,...,2} {      \pgfmathsetmacro{\st}{(((\r-1)*3)+\c)}      \pgfmathsetmacro{\en}{\st+1}      \draw[dagconn] ([xshift=0.2cm]x\st) to ([xshift=-0.9cm]x\en);    }  }   \foreach \c in {1,...,3} {    \foreach \r in {1,...,1} {      \pgfmathsetmacro{\st}{((\r-1)*3)+\c}      \pgfmathsetmacro{\en}{\st+3}      \draw[dagconn] (x\st) to (x\en);    }  } \end{tikzpicture} \end{document} Why is the CDF of a sample uniformly distributed I read  that given a sample $ X_1,X_2,...,X_n $ from a continuous distribution with cdf $ F_X $, the sample corresponding to $ U_i = F_X(X_i) $ follows a standard uniform distribution.  I have verified this using qualitative simulations in Python, and I was easily able to verify the relationship.  import matplotlib.pyplot as plt import scipy.stats  xs = scipy.stats.norm.rvs(5, 2, 10000)  fig, axes = plt.subplots(1, 2, figsize=(9, 3)) axes[0].hist(xs, bins=50) axes[0].set_title("Samples") axes[1].hist(     scipy.stats.norm.cdf(xs, 5, 2),     bins=50 ) axes[1].set_title("CDF(samples)")   Resulting in the following plot:    I am unable to grasp why this happens. I assume it has to do with the definition of the CDF and it's relationship to the PDF, but I am missing something...  I would appreciate it if someone could point me to some reading on the subject or help me get some intuition on the subject.  EDIT: The CDF looks like this: Is it okay to use the phrase "try and"? Is it grammatically correct? e.g. "I will try and answer ..." I read the following sentence in book (App).     I will try and answer any questions you ask.   Why don't they use the following? (it is much common):     I will try to answer any questions you ask.   Is there any difference in meaning?  Update:  I noticed that a lot of books and news websites are using this phrase:        Although Katty will try and answer as many questions as she can.    He puller would have a chance to try and answer the question on her own ... How to update libavcodec on ubuntu 14.04? On Ubuntu 14.04.5 I just upgraded firefox to version 50.0; now there is a message on some pages which reads:   libavcodec may be vulnerable or is not supported, and should be updated to play videos   So how can I update libavcodec?  A simple   sudo apt-get install libavcodec   gives the following output:  Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package libavcodec   So maybe I don't have libavcodec installed in the first place? So why do I get this message...?