Blank images on copy paste from pdf to image editor or LibreOffice Lately I have to extract few specific images from .pdf files and save them as image file. For example, the following is the image copied from a PDF (right click and copy image using Ctrl+C).    When I paste the same either in LibreOffice Writer or an image editor like KolourPaint, I end up with a blank image something like this. Can anyone suggest how I can work around this issue?
Extracting embedded images from a PDF Before I started using Ubuntu I used Nitro PDF reader to automatically extract images from PDF files. Is there a PDF reader for Linux that does this?  I would like to be able to extract images faster/easier than when taking a snapshot.
Links in [link text][number] format don't work properly if they follow a tag using the new [tag:tagName] format. Here's the result of [tag:python] [gold badge page][1]:      [gold badge page]   Putting the tag inside the link is worse. Here's the result of [[meta-tag:bug] some text][2], where [2] is google.com:        The part of the link outside the tag just disappears silently.  EDIT: To be more precise, the entire link to [2] disappears. The markup that is produced contains (invalid) nested anchor tags, as shown here from Firefox's "View Source":  &lt;a href="http://google.com" rel="nofollow"&gt;&lt;a href="/questions/tagged/bug" class="post-tag required-tag" title="show questions tagged 'bug'" rel="tag"&gt;bug&lt;/a&gt; some text&lt;/a&gt;   So the tag is still a link, but it is a link to the tag page, which is the behavior it would have if the link to [2] didn't exist at all. The user's desired behavior in this case is... ambiguous, to be charitable.  EDIT 2: I briefly included markup from Firebug here, but it turned out to be irrelevant. It has now been removed to improve readability. See  if you're interested. Jordan Canonical Form determined by characteristic and minimal polynomials in dimension $3$, but not beyond Why and how is the  of a matrix in $M_3(\mathbb C)$ fully determined by its characteristic and minimal polynomials? And why does it fail for $n &gt;3$?   Thanks. Deriving the speed of the propagation of a change in the Electromagnetic Field from Maxwell's Equations I've been told that, from Maxwell's equations, one can find that the propagation of change in the Electromagnetic Field travels at a speed $\frac{1}{\sqrt{\mu_0 \epsilon_0}}$ (the values of which can be empirically found, and, when plugged into the expression, yield the empirically found speed of light)  I'm really not sure how I would go about finding $v = \frac{1}{\sqrt{\mu_0 \epsilon_0}}$ simply from Maxwell's equations in the following form, in SI units --  $$\nabla \cdot \mathbf{E} = \frac {\rho} {\epsilon_0}$$  $$\nabla \cdot \mathbf{B} = 0$$  $$\nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}} {\partial t}$$  $$\nabla \times \mathbf{B} = \mu_0 \left( \mathbf{J} + \epsilon_0 \frac{\partial \mathbf{E}} {\partial t} \right)$$  Is what I believe true? (that the speed of propagation is derivable from Maxwell's Equations)  If not, what else is needed?  If so, can you provide a clear and cogent derivation? When is $(p - 1)! + 1$ a power of $p$? A friend asked me this question:     If $p$ is a prime, prove that $(p - 1)! + 1$ is a power of $p$ if and only if $p = 2, 3$ or $5$.   Clearly one direction is obvious, namely that $p=2,3,5$ implies $(p - 1)! + 1$ is a power of $p$.  The other direction is not clear to me. Since by Wilson's theorem $p$ divides $(p - 1)! + 1$ so we need to show that if there are no other prime factors then $p=2,3,5$. Can someone give me a hint for establishing this?  Thanks Best word wrap algorithm? Word wrap is one of the must-have features in a modern text editor.  How word wrap be handled? What is the best algorithm for word-wrap?  If text is several million lines, how can I make word-wrap very fast?  Why do I need the solution? Because my projects must draw text with various zoom level and simultaneously beautiful appearance.  The running environment is Windows Mobile devices. The maximum 600&nbsp;MHz speed with very small memory size.  How should I handle line information? Let's assume original data has three lines.  THIS IS LINE 1. THIS IS LINE 2. THIS IS LINE 3.   Afterwards, the break text will be shown like this:  THIS IS LINE 1. THIS IS LINE 2. THIS IS LINE 3.   Should I allocate three lines more? Or any other suggestions? ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ In my .bib file, I have two entries with exactly the same author names:  @article{Seshadrinathan2010A-Subjective-St,     Author = {K. Seshadrinathan and R. Soundararajan and A. C. Bovik and L. K. Cormack}, ....  @article{Seshadrinathan2009Study-of-Subjec,     Author = {K. Seshadrinathan and R. Soundararajan and A. C. Bovik and L. K. Cormack}, ....   When cited after each other, and typeset with the IEEEtran bibliography style, the .bbl file reads:  \bibitem{Seshadrinathan2010A-Subjective-St} K.~Seshadrinathan, R.~Soundararajan, A.~C. Bovik, and L.~K. Cormack, ``A   subjective study to evaluate video quality assessment algorithms,''   \emph{SPIE Proceedings Human Vision and Electronic Imaging}, 2010.  \bibitem{Seshadrinathan2009Study-of-Subjec} ------, ``Study of subjective and objective quality assessment of video,''   \emph{IEEE Transactions on Image Processing}, 2009.   As you can see, the author names have been replaced with ------. It looks like this in the final PDF:    Is this normal behavior? Randomly populating procedural shape (or Image Texture) in Cycles TL;DR  How to take a shape or Image Texture and multiply it with random Location, Rotation and Scale along object:    Background  I have created my first procedural shape on my own from this function: $(x^2 + y^2 - 1)^3 - x^2y^3 = 0$   (big yay for math idiot)   Here is the result:    And I want to do something useful with it.  Research  I've tried to find something similar over the web (this is trending right now) and I'm surprised that this question wasn't asked before or I'm looking with wrong terms. I've tried random pattern, duplicating texture, populating image, random tiles, custom tiles and such. There is a lot about tiling textures but each and every Q&amp;A I've stumbled upon are about non overlapping ones. For example:            Tryout:  The only way I can think of this is to duplicate shape as a group and manually change values in Mapping Nodes:    As you can see this is... Well. Bad.  I've tried messing with Modulo, mixing Noise between vectors, using custom node groups for LocRotScale (thanks Gandalf) but results was none, thus nothing even to show.  Question  I want to populate this shape (or any other) along the object with random Location, Rotation and Scale - with control over its number/density and maybe variation strength.  Edit: I'm not looking for alternative methods of creating this setup such as Particles, Image Textures generated in 3rd party software, OSL shaders (CPU only) and such. My intention is to use this in procedural texture generation in Cycles with GPU support.  Blend file  Nothing really needed for this question but here - have this heart from me :) How do I correctly tag my questions? Here are some tips for tagging questions. These guidelines will help you more accurately tag your questions, which in turn will help them get more attention and lead to better answers faster.     For more information, see "" in the . On the usage of "the" article with acronyms and initialisms I've read  and  I know that  1. The article is often used with initials that are pronounced letter by letter (initialisms).  2. The article is often NOT used with initials that are pronounced as a word (acronyms).  I used 'often' because I'm not sure about possible exceptions.  In my field of study (Operations Research), initials are frequently used to represent optimization problems (e.g., the TSP). I discussed this point with my university supervisor who makes comments on my reports (English is not his native language). He responded that:  "What I learned from [...] was that whenever we use (specific) acronyms, we don't use 'the' when they are within a sentence, and we use 'the' when a sentence starts with them. For instance,  (i) The HCP is an NP-Complete problem.  (ii) We developed a new algorithm to solve HCP."  HCP stands for the Hamiltonian Cycle Problem. It is really confusing me because I do not know when to use and when not to use the article. For example, on , the author Jane Watson writes:     Use a definite article with an initialism if the spelled out term begins with “the” but is not covered in the initialism.   which implies that I should use the article with "HCP". What do you think? Find a circle's radius with three known tangent lines I need to find the equation for a circle (mainly its radius) which is tangent to the following three lines:  $y = 0$  $y = \tan(70)x$  $y = -1.428148x + 0.790201$  For the last tangent line equation, I know that it is tangent at the point $(0.371272, 0.259968)$ However, for the other two I do not know the exact point of tangency, only that the circle is tangent to them. Should 'Hi', 'thanks', taglines, and salutations be removed from posts? I edit a lot of posts every day. I often run across posts with 'Hi' and 'Thanks' on the top and the bottom of the post respectively. I also run across things like:     --User   Should these items be removed during the editing of the post by an editor? facing difficulty to create dynamic xpath for City field of UTest website I am beginner in automation field, I am trying to automated one of the module, I have tried many different XPATH to fetch proper XPATH for City field o UTest site. Im trying to automate registration module as one of my assignment. I have tried my different xpath example below:  //xpath="//body/div[@class='pac-container pac-logo']/div/span[2]/span" //div[@class='pac-item']/span[3] //div[@class='pac-item']/span //div[@class='pac-container pac-logo']/div/span[2]/../span[3]   the following code written:  //xpath to send data in field @FindBy(xpath="//input[@placeholder='Enter a location']") WebElement city;  //xpath for list to appear @FindBy(xpath="div[@class='pac-item']/span") List&lt;WebElement&gt; City;  public void EnterSignupTwo(String CiTy) throws Exception {     city.clear();     city.sendKeys(CiTy);     Thread.sleep(3000);     System.out.println("the size of List " +City.size());//printing list size      for(int i=0; i&lt;City.size(); i++ ) {         String cities = City.get(i).getText(); //storing list element in String         System.out.println("Converted value of city :"+cities); //print of total list      if(cities.contains(CiTy)) //if parameterized match with Available then click     {         System.out.println("enter specific value of city :"+City.get(i).getText());         City.get(i).click();         break;     } }   kindly refer the I have created screenShot() method to take the screenshot of the web page. When I used this method in my code first time it will capture the screen and it will save the image with image1 name. When I used the same method screenShot() to capture screens for other pages with the use of this.screenShot(); this will again capture the current web page screen but it stores With the same name image1 in the same folder (which overrides to previously captured screen image1).  Now, I have to take screenshots for the number of web pages &amp; want to store it into the same folder with different names like image1, image2, image3...etc. by using the same method screenShot().  public void screenShot() throws IOException, InterruptedException {     File scr = ((TakesScreenshot)driver).getScreenshotAs(OutputType.FILE);     File dest = new File("filPath/image1.png");     FileUtils.copyFile(scr, dest); }   Any workaround to achieve this scenario? distribution upgrade 14.04 to 15.04 halted due to multiple errors When is it ok to remove the intercept in a linear regression model? I am running linear regression models and wondering what the conditions are for removing the intercept term.   In comparing results from two different regressions where one has the intercept and the other does not, I notice that the $R^2$ of the function without the intercept is much higher. Are there certain conditions or assumptions I should be following to make sure the removal of the intercept term is valid? How can you detect if users have created sock puppet accounts? How many users have created more than one profile on SO to vote themselves on their other original profile? There are some benefits when you have more reputation and sometimes you don't want a single -1 vote on your question or answer. In this case you may have an extra account to convert that -1 vote into 0 vote and  upvote for each of your questions and answers to gain reputation. I think it is not a good thing to do as a good developer.  Is there any way to recognize this situation? I think there should be some stats in each user's profile about how many votes are posted by each user on him/her or something like that.  So how many users have more than one profile? How to handle this situation? I have not created one yet but............ I don't think so :) How To quickly do derivatives with respect to matrices Whats a quick way to work the below (and problems similar) out?   For me to take this derivative it involves a lot of time and boring calculation, there has to be a better way.    This is taken from the solutions to Chris Bishop's Pattern Recognition and Machine learning: I noticed that I can only perform certain actions such as commenting a finite number of times in a given period of time. Obviously, rate limiting is in place to prevent accidental misuse or intentional abuse of certain features.  Where else is rate limiting applied on Stack Exchange sites, and what are the limits? Eclipse error: "The import XXX cannot be resolved" 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 ...