let $z$ be a complex variable and $z=0+0i$ , it is clear at all if want to compute $\arg(z)$ then should be check the value of $\tan^{-1}(y/x)$  then $\tan^{-1}(0/0)$ could be $0$ since $0 |0 $ using the divisibility notion or Is it possible to say that $\arg(0)= \infty $ since it's not undefined  ? Where is the approach definition ?
When $z\neq 0$, $\arg z$ is defined to be the set $\{\theta \in \mathbb{R} : z=|z|e^{i\theta}\}$.  What if $z=0$? Usually does one leave the argument of $0$ undefined? Or is $\arg 0 = \mathbb{R}$?
We have been using Notes and Attachment to store files related to the record. I also read about Files in salesforce.   How are Files different from Attachment? Are there any limitations or benefits of using Files instead of Attachments?  Are Files available for all editions of Salesforce?  Is it possible to link Files to particular records so they are visible as related list? I tried looking into the content version  but cant seem to find anything to relate to a record Suppose that we have a vector space $V$ and the subspaces $U=\{(x,x,y,y)\in F^4:x,y\in F\}$ and $W=\{(x,x,x,y)\in F^4:x,y\in F\}$. Then how comes $$U+W=\{(x,x,y,z)\in F^4:x,y,z\in F\}?$$ I'm not sure if this is possible architecturally, but when judging whether to set a bounty and how much it should be, it would be nice to see the impact based on our previous questions. If you're not visiting the site throughout the day, there is no way to tell how effective that bounty might be--particularly for increasing traffic. There is a similar question with adding and removing tags that increase the visibility in the right places, and the effect on views that may have. Regarding running Watir scripts for UI Automation from Jenkins CI - How to hook up Jenkins and watir-automations My account has 20 (!) sites associated to it.  I only use it for 3-5 sites.  To reduce clutter, I would like to delete my profiles that I do not use much.  I have went through , but when I enter the profile URL as:  http://russian.stackexchange.com/users/5772/alex   it gives the error message:     oops! this isn't a link to a valid profile   What procedure do I go through to delete my profile only on certain sites? Encode URL in JavaScript? Linear regression in a loglog-plot with fixed slope Goal: create a plot to compare the empirical convergence rate of a numerical method with the one expected from the theory.  Accordingly, given a loglog-plot, I would like to add the line which has a prescribed slope (in this case, the convergence of the method) and the best intercept to fit the data (e.g., in a least-square sense).  Question: how to do a linear regression with fixed slope in pgfplots?  What I have done so far is the following: (1) compute the regression line (of the logarithm of the quantities), (2) save the intercept, (3) plot the line with the slope expected from the theory and this intercept.  This is a good approximation of what I am looking for, provided the data are in agreement with the theory.  Thanks  MdFB I'm a citizen of an EU member state traveling to a small city in Vermont. Looking at flight data, it seems that it would be quite a bit quicker to fly into Montreal (Canada) and then drive a rental car to my final destination in Vermont (and back), rather than getting a connecting flight into a small local US airport. I am slightly worried about the trouble I might get myself into by crossing a land border twice, though.  Can anyone give me an idea of what I'd be getting into in terms of:   Crossing time Discomfort Additional paperwork required   For both the outbound (Canada/US) and the return leg (US/Canada) of my journey, when compared to crossing the border at an international airport?  Also, do I need to take any special actions when I'm arranging a rental car if I intend to drive it over to the US and back? I am constructing a thought experiment about a spinning object that is floating in intergalactic space.  I assume that this object is about the size of a planet so that it will have enough gravity so that a Foucault pendulum will work, although I'm not sure that this is necessary for the thought experiment.    I can easily determine that this object is spinning if I stand on the object and observe the galaxies around me rise and set.  Similarly, I can determine the axis of rotation.    For simplicity, I go to one of the poles of my object, and I set up my Foucault pendulum.  What will I see?  And why will I see it?  I assume that in intergalactic space, the gravity is very small (galaxies are very far away, and the mass of my object is very small compared to the mass of a galaxy) so that there will be little coupling between the gravitational field of my object and the gravitational field of the galaxies around me. It's time to remove the bounty delay What are Virtual Methods? Why would you declare a method as "virtual".   What is the benefit in using virtual? Range of $(a_{1}-a_{2})^2+(a_{2}-a_{3})^2+(a_{3}-a_{4})^2+(a_{4}-a_{1})^2$ is If $a_{1},a_{2},a_{3},a_{4}\in \mathbb{R}$ and $a_{1}+a_{2}+a_{3}+a_{4}=0$ and $a^2_{1}+a^2_{2}+a^2_{3}+a^2_{4}=1.$ Then Range of $$E =(a_{1}-a_{2})^2+(a_{2}-a_{3})^2+(a_{3}-a_{4})^2+(a_{4}-a_{1})^2$$ is  Try: From $$(a_{1}-a_{2})^2+(a_{2}-a_{3})^2+(a_{3}-a_{4})^2+(a_{4}-a_{1})^2$$ $$=2(a^2_{1}+a^2_{2}+a^2_{3}+a^2_{4})+2(a_{1}a_{2}+a_{2}a_{3}+a_{3}a_{4}+a_{4}a_{1})$$ $$=2-2(a_{1}+a_{3})(a_{2}+a_{4})=2+2(a_{1}+a_{3})^2\geq 2$$ and equality hold when $\displaystyle a_{1}=-a_{3}$ and $a_{2}=-a_{4}$ Could some help me how to find its upper bound, Thanks How do I copy to the clipboard in JavaScript? What is the best way to copy text to the clipboard (multi-browser)? I have tried: function copyToClipboard(text) {     if (window.clipboardData) { // Internet Explorer         window.clipboardData.setData(&quot;Text&quot;, text);     } else {         unsafeWindow.netscape.security.PrivilegeManager.enablePrivilege(&quot;UniversalXPConnect&quot;);         const clipboardHelper = Components.classes[&quot;@mozilla.org/widget/clipboardhelper;1&quot;].getService(Components.interfaces.nsIClipboardHelper);         clipboardHelper.copyString(text);     } }  But in Internet Explorer it gives a syntax error. In Firefox, it says unsafeWindow is not defined. A nice trick without using : How to automatically resize the vertical bar in a set comprehension? I have a simple command which I use to write set comprehensions so that the braces automatically resize with respect to size of the enclosed arguments, e.g.  \usepackage{amsmath} \newcommand{\set}[1]{\left\lbrace #1\right\rbrace}  \begin{equation*} \set{x \in X \mid x &gt; \frac{1}{2}}   \end{equation*} % Produces something like: { x : X | x &gt; 1/2 }   However, the \mid vertical bar wont resize like the braces { .. } do. How can I get the \mid to resize as well? I am using Ubuntu 11.10 (64 bits) and I do not want to mount automatically USB thumb drives in my system. I tried the command dconf-editor and gconf-editor but there isn't the icon to disable it in nautilus preferences (apps|nautilus|preferences|media_automount).  Thanks. How to parse a date? Windows Power Options Clarification So I was looking through the Windows 7 power options via Control Panel today, and I realized I had a couple of unresolved questions as to the nature of various choices. I was wondering if someone could give me a clear and concise explanation of the difference between the following four selections:   Sleep Mode Hibernate Mode Standby Mode Turn off hard disks after...   For example, regarding option 4 - does this mean that after the elapsed time limit, the computer will go into standby, hibernate, sleep, or just turn off? Below is an image of the options (albeit on a Windows XP system, but I think the same concepts should apply): If you draw two cards, what is the probability that the second card is a queen? "World's Hardest Easy Geometry Problem" Evaluating $\int_0^{2 \pi} e^{\cos x} \cos (nx - \sin x) \,dx$ using complex analysis I'm taking a complex analysis course and doing some practice computing residues &amp; evaluating integrals. I pulled out an old book called     On page 196-197, there are some interesting integrals to evaluate. I'm at 5.4.3.10.: I was able to do question 1, but was stumped at how to even begin with question 2:     Evaluate the integral   $$\int_0^{2 \pi} e^{\cos x} \cos (nx - \sin x) \,dx ,$$   where $n$ is an natural number.   The answer is simply $\frac{2 \pi}{n}$. Any hints?