Color Image to Grey scale and RGB to CMYK Conversion
Is there a way to convert an image to grayscale?
Why do the $n \times n$ non-singular matrices form an "open" set? Why is the set of $n\times n$ real, non-singular matrices an  open subset of the set of all $n\times n$ real matrices? I don't quite understand what "open" means in this context.  Thank you. How to turn off "unread messages" feature on Windows XP login screen? In Windows XP, if you have logged onto Windows Live Messenger at some point, then it'll start displaying how many unread messages on the Windows login screen. How can I turn it off? I know I can only use the gym feature after hitting level 5, but are there any other privilege or rewards for the levels above 5?  For example, in Ingress, some items are only available for the higher level player. How about Pokemon Go? I know you can export the asset as a PSD and open it in Photoshop. Is there a more seamless way?  Update:  I'm an idiot.  Someone else created the logo, and the shadow was it's own layer on multiply and not a normal drop shadow effect. Is a NVIDIA GeForce with Optimus Technology supported by Ubuntu? How to get my own IP address and save it to a variable in a shell script? Is a differentiable function always continuous? Continuous Functions are not Always Differentiable. But can we safely say that if a function f(x) is differentiable within range $(a,b)$ then it is continuous in the interval $[a,b]$ . If so , what is the logic behind it ? Understanding how references and labels work I'm trying to understand why I cannot effectively reference figures or equations that I have defined with labels.  For example:  \begin{figure}   \label{fig:area_Treasuries}   \caption{Treasuries as a portion of total financial flows.}   \centering   \includegraphics[width=0.75\textwidth]{graphs/Area_Treasuries.png} \end{figure}  \paragraph{} Figure~\ref{fig:area_Treasuries} presents Treasuries (both flowing into and out of the United States) as a share of total financial flows.  From 1985 to 2010, Treasuries account for, on average, 53.2\% of total financial flows.   With the above code, I get this warning:      LaTeX Warning: Reference `fig:area_Treasuries' on page 37 undefined on   input line 477.   The result is "Figure ?? presents Treasuries..."  Why is this happening?  Related, I don't understand why I can't reference, say, an equation before (I mean physically above in the text) the actual equation.  Isn't this what compiling multiple times and cross references is supposed to take care of? I'm very confused about tenses.  I have examples in two different situations here. Situation 1: I went to New York two months ago and was talking to someone about it.  A. This is the first time I've been to New York. B. That was the first time I'd been to New York.  Which is correct in a daily conversation?  Situation 2: I'm going to New York next month and talking to someone.  A. This will be the first time I've been to New York. B. This is the first time I've been to New York. C. This will be the first time I go to New York.  Which sentence is appropriate?  According to a grammar article I've read before, I think it says that I can use this sentence in both cases:  This is the first time I've been to New York.  But I'm not sure if this is really so. So I'd like to know which tense I should use in each case. Could you explain it? Boot screen in low graphics/text mode My ubuntu boot screen shows up in a strange low resolution, almost text mode, instead the usual and sleek white "ubuntu" over dark background. It's not a big issue because when GDM loads everything becomes ok, but If there's an easy way to fix it I would like to give it a try. Every time since a few days ago after I caught Mespirit, when I go to the portal in the Nameless Cavern and I press A to interact. All that happens is a short dialog sequence and nothing else. I know the requirements are along the lines of having 3 max happiness Pokemon with you in your party which I do. I have also downloaded the recent update/patch from the eShop if that helps at all. How can I make Uxie and Azelf appear in the cavern? Proof: Show there is set of $n+1$ points in $\mathbb{R}^n$ such that distance between any two distinct points is $1$? I have a question about subsets $$ A \subseteq \mathbb R $$ for which there exists a function $$f : \mathbb R \to \mathbb R$$ such that the set of continuity points of $f$ is $A$. Can I characterize this kind of sets? In a topological,measurable or in some way? For example, does there exist a function continuous on $\mathbb Q$ and discontinuous on the irrationals? I have played the game Othello (Reversi) numerous times but I never approach it with a specific logic or algorithm to apply on each move in my mind. I won many times and lost as much. How would one approach this game? How would one work in his mind to prune the possible moves and choose the &quot;right&quot; one in each step? I see that most Othello CPUs more or less &quot;think&quot; the same at each move, how should I think on each move? How many irreducible monic quadratic polynomials are there in $\mathbb{F}_p[X]$? Can some of you help me with my homework?     I had to count the irreducible, quadratic, monic polynomials in $\mathbb{F}_p[X]$ for arbitrary $p$.    I will show you what I tried myself.  Research effort  First of all the set $\{X^ 2 + bX +c : b, c \in \mathbb{F}_p \}$ contains $p^2$ elemenst. We need to substract the amount of elements that is reducible. These elements are exactly the set $A = \{(X+c)(X+d) : c, d \in \mathbb{F}_p \}$. There are $p(p-1)$ pairs of $(a,b) \in \mathbb{F}_p \times \mathbb{F}_p$ such that $a \neq b$, and there are $p$ pairs such that $a=b$.     When $a$ and $b$ are unequal, whe know that $a$ and $b$ can be swapped without changing anything to the polynomial $(X+a)(X+b)$, so I obtained that $|A| \leq p +(p-1)- \frac{1}{2}(p-1)=p-\frac{1}{2}(p-1)$.  In other to find out these are the elements, or that there are still less, I thought I had to assume that $(X+c)(X+d) = (X+\gamma)(X+\delta)$, to deduce some information about the realation between $(c,d)$ and $(\gamma, \delta)$, but this led to taking square roots in $\mathbb{F}_p$, and I am not familiar with that.  Could you please provide me some more information? "Fatal error: Class name must be a valid object or a string in C:\xampp\htdocs\uc\includes\common.inc on line 7506"  The error above showed up unexpectedly. I was adding a "Long text" field to a content-type, but when I expected to be brought to a saved field configuration page, I instead got a Fatal error on every page.  I had a look at includes\common.inc:  /**  * Get the entity controller class for an entity type.  */ function entity_get_controller($entity_type) {   $controllers = &amp;drupal_static(__FUNCTION__, array());   if (!isset($controllers[$entity_type])) {     $type_info = entity_get_info($entity_type);     $class = $type_info['controller class'];     $controllers[$entity_type] = new $class($entity_type); // Line 7506   }   return $controllers[$entity_type]; }   However, I just don't understand Drupal at a low enough level to understand the relationships between these variables and functions.  I also searched Drupal for people with a similar problem:  (1)  who claims that I have to install the submodule "Relation Endpoints Field", but searching Drupal, .  (2) :  DELETE FROM cache; DELETE FROM cache_filter; DELETE FROM cache_menu; DELETE FROM cache_page; DELETE FROM watchdog;   (via , misleading name, I know.)  Clearing those tables from the cache did not help.  (3) And another user . Because I can't find a module specifically pertaining to old search facets, I went into MySQL system table, and marked the Search module's line with a 0 status, indicating to stop loading the module altogether.  On that same link as (3), one user suggested enabling the , so I dropped all the tables, imported the latest stable .sql, and installed the module, but after recreating the problem (trying to add a field to a content-type), that as well concluded fruitless.  Still, the problem remains  The Fatal error shows up on every page, making the site completely non-functional. Any help or direction would be immensely appreciated. Thank you for looking. Explaining Horizontal Shifting and Scaling I always find myself wanting for a clear explanation (to a college algebra student) for the fact that horizontal transformations of graphs work in the opposite way that one might expect.  For example, $f(x+1)$ is a horizontal shift to the left (a shift toward the negative side of the $x$-axis), whereas a cursory glance would cause one to suspect that adding a positive amount should shift in the positive direction. Similarly, $f(2x)$ causes the graph to shrink horizontally, not expand.  I generally explain this by saying $x$ is getting a "head start". For example, suppose $f(x)$ has a root at $x = 5$. The graph of $f(x+1)$ is getting a unit for free, and so we only need $x = 4$ to get the same output before as before (i.e. a root). Thus, the root that used to be at $x=5$ is now at $x=4$, which is a shift to the left.  My explanation seems to help some students and mystify others. I was hoping someone else in the community had an enlightening way to explain these phenomena. Again, I emphasize that the purpose is to strengthen the student's intuition; a rigorous algebraic approach is not what I'm looking for. What is involved in moving over to Lightning Web Components? Performance of a Trigger vs Stored Procedure in MySQL Wrong pluralization on accounts tab of user profile Under accounts tab of a user's profile, words questions and answers are used even when count is 1. For live example, you can go to my profile &amp; click accounts tab. Scroll down to Drupal Answers row where you can find &quot;1 answers&quot; which should be &quot;1 answer&quot;. Or, scroll down to Server Fault row to see both &quot;1 questions&quot; and &quot;1 answers&quot;.