Python constructor overload with different number of parameters
How to overload __init__ method based on argument type?
If $X$ is distributed $N(\mu_X, \sigma^2_X)$, $Y$ is distributed $N(\mu_Y, \sigma^2_Y)$ and $Z = X + Y$, I know that $Z$ is distributed $N(\mu_X + \mu_Y, \sigma^2_X + \sigma^2_Y)$ if X and Y are independent.  But what would happen if X and Y were not independent, i.e. $(X, Y) \approx N\big( (\begin{smallmatrix} \mu_X\\\mu_Y \end{smallmatrix}) , (\begin{smallmatrix} \sigma^2_X &amp;&amp; \sigma_{X,Y}\\ \sigma_{X,Y} &amp;&amp; \sigma^2_Y \end{smallmatrix}) \big) $  Would this affect how the sum $Z$ is distributed? How does the CS:GO ranking system work? This question is a sequel of sorts to my  about .  In the paper, the authors performed molecular dynamics (MD) simulations of parallel-plate supercapacitors, in which liquid resides between the parallel-plate electrodes.  The system has a "slab" geometry, so the authors are only interested in variations of the liquid structure along the $z$ direction.  In my previous question, I asked about how particle number density is computed.  In this question, I would like to ask about how the electric potential is computed, given the charge density distribution.  Recall that in CGS (Gaussian) units, the Poisson equation is   $$\nabla^2 \Phi = -4\pi \rho$$  where $\Phi$ is the electric potential and $\rho$ is the charge density.  So the charge density $\rho$ is proportional to the Laplacian of the potential.  Now suppose I want to find the potential $\Phi(z)$ along $z$, by integrating the Poisson equation.  How can I do this?  In the paper, on page 254, the authors write down the average charge density $\bar{\rho}_{\alpha}(z)$ at $z$:  $$\bar{\rho}_{\alpha}(z) = A_0^{-1} \int_{-x_0}^{x_0} \int_{-y_0}^{y_0} dx^{\prime} \; dy^{\prime} \; \rho_{\alpha}(x^{\prime}, y^{\prime}, z)$$  where $\rho_{\alpha}(x, y, z)$ is the local charge density arising from the atomic charge distribution of ionic species $\alpha$, $\bar{\rho}_{\alpha}(z)$ is the average charge density at $z$ obtained by averaging $\rho_{\alpha}(x, y, z)$ over $x$ and $y$, and $\sum_{\alpha}$ denotes sum over ionic species.  The authors then integrate the Poisson equation to obtain $\Phi(z)$:  $$\Phi(z) = -4\pi \sum_{\alpha} \int_{-z_0}^z (z - z^{\prime}) \bar{\rho}_{\alpha}(z^{\prime}) \; dz^{\prime} \; \; \; \; \textbf{(eq. 2)}$$  My question is, how do I "integrate the Poisson equation" to obtain equation (2)?  How do I go from  $\nabla^2 \Phi = -4\pi \rho$ to equation (2)?  In paricular, where does the $(z - z^{\prime})$ factor come from?   Thanks for your time. Fontconfig warning: "/etc/fonts/conf.d/90-fonts-unfonts-core.conf" I am getting the following error frequently. (Example: when running zenity,firefox etc. commands / applications.)  Fontconfig warning: "/etc/fonts/conf.d/90-fonts-unfonts-core.conf", line 11: Having multiple values in &lt;test&gt; isn't supported and may not work as expected   Here is contents of file /etc/fonts/conf.d/90-fonts-unfonts-core.conf:  &lt;?xml version="1.0"?&gt; &lt;!DOCTYPE fontconfig SYSTEM "fonts.dtd"&gt; &lt;fontconfig&gt;     &lt;match target="font"&gt;         &lt;test name="family" qual="any"&gt;             &lt;string&gt;은 바탕&lt;/string&gt;&lt;string&gt;UnBatang&lt;/string&gt;                 &lt;string&gt;은 돋움&lt;/string&gt;&lt;string&gt;UnDotum&lt;/string&gt;                 &lt;string&gt;은 궁서&lt;/string&gt;&lt;string&gt;UnGungseo&lt;/string&gt;                 &lt;string&gt;은 필기&lt;/string&gt;&lt;string&gt;UnPilgi&lt;/string&gt;                 &lt;string&gt;은 그래픽&lt;/string&gt;&lt;string&gt;UnGraphic&lt;/string&gt;         &lt;/test&gt;          &lt;edit name="antialias" mode="assign" binding="strong"&gt;&lt;bool&gt;true&lt;/bool&gt;&lt;/edit&gt;         &lt;edit name="hinting"   mode="assign" binding="strong"&gt;&lt;bool&gt;false&lt;/bool&gt;&lt;/edit&gt;         &lt;edit name="autohint"  mode="assign" binding="strong"&gt;&lt;bool&gt;true&lt;/bool&gt;&lt;/edit&gt;         &lt;edit name="hintstyle" mode="assign" binding="strong"&gt;&lt;const&gt;hintslight&lt;/const&gt;&lt;/edit&gt;     &lt;/match&gt; &lt;/fontconfig&gt;   How to solve it? How do you access browser history? Some e-Marketing tools claim to choose which web page to display based on where you were before. That is, if you've been browsing truck sites and then go to Ford.com, your first page would be of the Ford Explorer.  I know you can get the immediate preceding page with HTTP_REFERRER, but how do you know where they were 6 sites ago? Equicontinuity on a compact metric space turns pointwise to uniform convergence I know that   If $\{f_n\}$ is an equicontinuous sequence,  defined on a compact metric space $K$, and for all $x$, $f_n(x)\rightarrow f(x)$, then $f_n\rightarrow f$ uniformly.  I'm having trouble proving this.  I see the same problem  but am having trouble following the proof, particularly with part (3).  Can someone guide me through a proof of this result? Proving that $ 2 $ is the only real solution of $ 3^x+4^x=5^x $ Does iOS have a firewall? Does iOS support a built-in firewall like macOS does? I don't see anything about it in Settings. Suppose $f$ is continuous on $[a,b]$ and differentiable on (a,b). Does it follow that $f'$ is continuous on $(a,b)$? CSS to make HTML page footer stay at bottom of the page with a minimum height, but not overlap the page If everything in the universe doubled in size overnight, would it be noticeable? Show question ID When I want to close a question as duplicate using the app, I have to enter the question ID as usual. Problem is, as far as I can tell, the question IDs are shown nowhere! Please add the ID somewhere. Easy is to beginner as medium is to I want to display three levels in my game...but I don't know what the text should say.  easy -&gt; Beginner  medium -&gt; ?  hard -&gt; Expert   Basically, I want the form that describes the person playing the game, instead of the game itself. What adjective is best?  I have considered adept.  I doubt my users will know what adept means. Also, I need something in between expert and beginner. Adept falls into the expert category. Is there anything more common that I can use, that has the same impact as the other two words I mentioned?  Proficient would work, theoretically, but in day-to-day term, the levels "beginner - proficient - expert" won't sound great. In a family with two children, what are the chances, if one of the children is a girl, that both children are girls?  I just dipped into a book, The Drunkard's Walk - How Randomness Rules Our Lives, by Leonard Mlodinow, Vintage Books, 2008. On p.107 Mlodinow says the chances are 1 in 3.   It seems obvious to me that the chances are 1 in 2. Am I correct? Is this not exactly analogous to having a bowl with an infinite number of marbles, half black and half red? Without looking I draw out a black marble. The probability of the second marble I draw being black is 1/2. Imagine that a PC gets reduced to 0 hit points during a battle. The battle continues for a couple more rounds and they roll their death saves, one success and one failure (not sure if this part of the question is relevant).  Then the rest of the party defeats the last enemy and battle is over. Now what?    Does the downed PC keep rolling death saves until they strike 3 one way or the other? Does everyone else repeatedly roll for Medicine to stabalise the dying PC? Or (as we've been ruling it) they are just assumed to become stabilised because combat is over (I'm fairly certain this probably isn't RAW or RAI though).   I've looked through the PHB and I've only managed to find descriptions of being stabilised during combat, not after it.  Ideally I'd like a rule quoted (or a tweet or something) to point to where such a thing is outlined in the rules, if it is written anywhere. I'm a C++ guy learning Java. I'm reading Effective Java and something confused me. It says never to write code like this:  String s = new String("silly");   Because it creates unnecessary String objects. But instead it should be written like this:  String s = "No longer silly";   Ok fine so far...However, given this class:  public final class CaseInsensitiveString {     private String s;     public CaseInsensitiveString(String s) {         if (s == null) {             throw new NullPointerException();         }         this.s = s;     }     :     : }  CaseInsensitiveString cis = new CaseInsensitiveString("Polish"); String s = "polish";    Why is the first statement ok? Shouldn't it be   CaseInsensitiveString cis = "Polish"; How do I make CaseInsensitiveString behave like String so the above statement is OK (with and without extending String)? What is it about String that makes it OK to just be able to pass it a literal like that? From my understanding there is no "copy constructor" concept in Java? Is it possible to install an old version of Mac OS on a new Mac? How can I set up password-less SSH login? I want to be able to login to a remote via ssh without having to enter the password all the time.   How do I set it up? Is a different command required to execute a password-less session? What exactly happened with Dr. Crusher's husband and Captain Picard? How do I change the screen resolution using Ubuntu command line? I installed Ubuntu and the resolution of the desktop is so big that it only shows about 50% of the screen, but is shows up normal while using command line.   What should I type in the command line to change the desktop screen resolution?