I would like to draw the following two images. I heard using tikz may be of some help.
I would like to typeset some easy polyomino puzzles and therefore need a suitable LaTeX package. I could not find an easy to use package (other than using TikZ of course). Is there any approach other than using TikZ/PSTricks?  For anybody not aware of what polyominos are:   Edit: With a polyomino puzzle, I mean something like this:   So my intention is to put a set of polyominos into a given shape.
Lazy Eye in Infants, Preparations for Seeing a Specialist My youngest (14 months) has started showing signs of either strabismus or ambylopia (both commonly referred to as "lazy eye", where one eye seems to track differently than the other when the child is tired or isn't focusing).  We're going to see an ophthalmologist once the pediatrician weighs in and recommends one, and I'm interested in suggestions for what I should look for in an ophthalmologist, and in what we should do to prepare for the visit.  Particularly, how important is it that we find one that specifically mentions these conditions as things they specialize in?  They're fairly common conditions (affecting over 4% of children), so I would expect most pediatric ophthalmologists to have as one of their main purposes helping to diagnose and treat lazy eyes; but many do not mention them in their list of specializations.    And, in terms of preparation, do we need to keep track of time or length of lazy eye bouts?  Should we take any videos?  Our pediatrician hasn't noticed this in her periodic checks, but I suspect that he's more focused during these visits (a person he's not that used to, who is talking a lot to him).  I worry the ophthalmologist will have the same problem - not be able to diagnose because of lack of presentation during the visit. I've created a bash script but when I try to execute it, I get   #!/bin/bash no such file or directory   I need to run the command: bash script.sh for it to work.  How can I fix this? All I want to do is to check whether an element exists in the vector or not, so I can deal with each case.  if ( item_present )    do_this(); else    do_that(); Good books on "advanced" probabilities Effect of switching response and explanatory variable in simple linear regression Let's say that there exists some "true" relationship between $y$ and $x$ such that $y = ax + b + \epsilon$, where $a$ and $b$ are constants and $\epsilon$ is i.i.d normal noise. When I randomly generate data from that R code: x &lt;- 1:100; y &lt;- ax + b + rnorm(length(x)) and then fit a model like y ~ x, I obviously get reasonably good estimates for $a$ and $b$.  If I switch the role of the variables as in (x ~ y), however, and then rewrite the result for $y$ to be a function of $x$, the resulting slope is always steeper (either more negative or more positive) than that estimated by the y ~ x regression. I'm trying to understand exactly why that is and would appreciate it if anyone could give me an intuition as to what's going on there. I have Ubuntu 14.04 installed on my laptop. Can I clone the entire system with apps, settings, etc on a USB 3 pendrive, and then boot from that on other computers as a portable Ubuntu installation to take around with me?  I am trying a function that Timeshift has that's called "Clone the current system on another device". I've selected the pendrive as the target device. Timeshift was talking about this being bootable. But is it going to bootable on only this laptop, or on any system? For example, on an Intel Mac, or a Windows computer without the grub bootloader? Is that Timeshift function what I am looking for, or do I have to do something else?  Edit: The Timeshift clone failed to boot on the first system I tested it on. (A Dell Hackintosh that usually boots from USB just fine.) using Ajax with 3 consecutive drop down lists depending on eachother long long implementation in 32 bit machine As per c99 standard, size of long long should be minimum 64 bits. How is this implemented in a 32 bit machine (eg. addition or multiplication of 2 long longs). Also, What is the equivalent of long long in C++. I am writing a client-side Swing application (graphical font designer) on Java 5. Recently, I am running into java.lang.OutOfMemoryError: Java heap space error because I am not being conservative on memory usage. The user can open unlimited number of files, and the program keeps the opened objects in the memory. After a quick research I found  and others saying on Windows machine the JVM defaults max heap size as 64MB.  Given this situation, how should I deal with this constraint?  I could increase the max heap size using command line option to java, but that would require figuring out available RAM and writing some launching program or script. Besides, increasing to some finite max does not ultimately get rid of the issue.  I could rewrite some of my code to persist objects to file system frequently (using database is the same thing) to free up the memory. It could work, but it's probably a lot work too.  If you could point me to details of above ideas or some alternatives like automatic virtual memory, extending heap size dynamically, that will be great. Why are there $1 / 1.602176634 \times 10^{-19}$ electrons in a coulomb? Why that exact number of electrons in one coulomb? who decided it? there is nothing wrong with the number, it just seems slightly messy. Why didn't the scientific community just settle on an easier number, such as $1\times10^{-19}$ for example? If I have example.com, and blog.example.com, do search engines see those as one site or two? Will using subdomains hurt SEO? I have some technical reasons why I can't use example.com/blog. How to inline expand wildcard in bash? I remembered bash can do the following:  Suppose there are 3 files: a,b,c in the current directory, when I input:  $&gt; somecommand *   and then press a key or key combinations or a key sequence, the wildcard * online expanded as:  $&gt; somecommand a b c   but I cannot remember and cannot google out the key sequence! help! How do I remove all sub-directories from within a directory? This question is kind of a phase II to the first question I posted at   I have a directory that contains a bunch of sub-directories, .zip files, and other random files not contained within a sub-directory.  I'd like a command line script to remove all sub-directories from within the parent directory, but keep all zip files and loose files that don't belong to any sub-directories. All of the sub-directories have content, so I believe I'd need to force their deletion with the -f command.  So basically, a command that looks inside the parent directory (or the current directory), deletes all folders from within it, but keeps all other content and files that are not a folder or contained within a folder.  I understand that deleting items from the command line requires special care, but I have already taken all necessary precautions to back up remotely. Why does do-release-upgrade on Xubuntu running version 18.04 not offer to update to 20.04.1? I've understood that when I run the Software Updater GUI program, or when I execute do-release-upgrade on the command line, it should offer to upgrade to the latest LTS release if (1) I've got the release update behaviour set to lts, and (2) if the first point release of a newer LTS release is available. I have a couple of machines running the Xubuntu LTS release 18.04. The contents of file etc/update-manager/release-upgrades on all these machines is [DEFAULT] Prompt=lts  That satisfies condition (1). Also, it seems that Xubuntu 20.04.1 is already released, satisfying condition (2). However, neither do-release-upgrade nor the Software Updater offers to upgrade to that release. Why? Edited to add: It seems this question is a duplicate of . How to get distance when acceleration is not constant? I have a background in calculus but don't really know anything about physics.  Forgive me if this is a really basic question.  The equation for distance of an accelerating object with constant acceleration is:  $$d=ut        +\frac{1}{2}at^2$$  which can also be expressed  $$d=\frac{\mathrm{d}x}{\mathrm{d}t}t+\frac{\mathrm{d^2}x}{\mathrm{d}t^2}\frac{t^2}{2}$$  (where x(t) is the position of the object at time t)  That's fine for a canonball or something like that, but what about a car accelerating from 0 to cruising speed?  The acceleration is obviously not constant, but what about the change in acceleration?  Is it constant?  I suspect not.  And then what about the change in the change of acceleration, etc. etc.?  In other words, how does one know how many additional terms to add in the series?  $$d=\frac{\mathrm{d}x}{\mathrm{d}t}t+\frac{\mathrm{d^2}x}{\mathrm{d}t^2}\frac{t^2}{2}+\frac{\mathrm{d^3}x}{\mathrm{d}t^3}\frac{t^3}{3}+\frac{\mathrm{d^4}x}{\mathrm{d}t^4}\frac{t^4}{4}\cdot etc. \cdot ?$$ How to start applications such as xcompmgr at start up? I've been trying to make xcompmgrto autostart in Lubuntu 11.10 but it just doesn't, I have to start it manually.  I have added the next lines to the autostart script in ~/.config/openbox/  #Run a composite manager xcompmgr &amp;   But whenever I log in it doesn't do anything, I don't really need any special parameters for it I just want it to start at log in.  How can I make it run automatically at login? Photoshop CC 2019: Pixelated Brush Stroke For some reasons my brush stroke suddenly looks like this:     As the picture showed, the edges are jagged and pixelated. It doesn't happen before and it's just one of the built-in inking brush.  I know there are a lot of similar questions here but please don't mark this as duplicate. I double checked all the thing the other answers suggested: It's brush tool, not pencil, and my mode of brush and layer is Normal, not Dissolve. It's pixelated even if I draw with mouse so it's not tablet driver issue. I disabled GPU render but nothing changed. How do I fix this? I am working on a git repository with a master branch and another topic branch. I have switched to topic branch and modified a file. Now, if I switched to master branch that same file is shown as modified.   For example:  git status in git-build branch:  # On branch git-build # Changes to be committed: #   (use "git reset HEAD &lt;file&gt;..." to unstage) # #       modified:   cvsup_current #   Switch to master branch  [root@redbull builder_scripts (git-build)]# git co master M       builder_scripts/cvsup_current Switched to branch "master"   git status in master branch  [root@redbull builder_scripts (master)]# git status # On branch master # Changes to be committed: #   (use "git reset HEAD &lt;file&gt;..." to unstage) # #       modified:   cvsup_current #   Why is that the file is shown as modified in master branch even though it was modified in git-build branch?   My understanding was that the branches are independent of each other and when I change from one branch to another the changes do not "spill over" from one branch to another. So I am obviously missing some thing here.   Anyone got a clue stick? How do I create an immutable Class? Why do we use "dried up" instead of just "dried"? The creek has dried up.   In this example sentence, you should say "dried up." If you say just "dried," it sounds incomplete. Is this an example of an idiom or is there a grammatical rule governing this instance? If so, what is it?