Polymorphism and overriding a method from a class template in C++
What is object slicing?
Is cancer caused by vitamin B17 deficiency? Can the Earth's magnetic field be used to generate electricity? Fspy add-on not installing I would like to know how to put a time delay in a Python script. Which "href" value should I use for JavaScript links, "#" or "javascript:void(0)"? The following are two methods of building a link that has the sole purpose of running JavaScript code. Which is better, in terms of functionality, page load speed, validation purposes, etc.?    function myJsFunc() {     alert("myJsFunc"); } &lt;a href="#" onclick="myJsFunc();"&gt;Run JavaScript Code&lt;/a&gt;     or    function myJsFunc() {     alert("myJsFunc"); }  &lt;a href="javascript:void(0)" onclick="myJsFunc();"&gt;Run JavaScript Code&lt;/a&gt; Most MTP () devices show up in Windows File Explorer under their device name or a GUID, but they don't have a drive letter assigned.  How can I access the files on such devices from the command line? Using either cmd.exe or PowerShell. Best word for "unable to change" Strange behaviour of 'sudo chmod -rwx': Does not remove group write permissions Why is log-of-sum-of-exponentials $f(x)=\log\left(\sum_{i=1}^n e^ {x_i}\right)$ a convex function for $x \in\mathbb R^n$? How to prove $f(x)=\log\left(\displaystyle\sum_{i=1}^n e^{x_i}\right)$ is a convex function?  EDIT1: for above function $f(x)$, following inequalities hold:  $$\max\{x_1,x_2,\ldots,x_n\}\leqslant f(x)\leqslant\max\{x_1,x_2,\ldots,x_n\}+\log n$$  and I have tried proving its convexity via definition of a convex function with above inequalities, but that didn't work.  EDIT2: I have posted my answers below. Why can't a normal user `chown` a file? Logistic regression in R resulted in perfect separation (Hauck-Donner phenomenon). Now what? I'm trying to predict a binary outcome using 50 continuous explanatory variables (the range of most of the variables is $-\infty$ to $\infty$). My data set has almost 24,000 rows. When I run glm in R, I get:  Warning messages:   1: glm.fit: algorithm did not converge   2: glm.fit: fitted probabilities numerically 0 or 1 occurred    I've read the other responses that suggest perfect separation might be occurring, but I'm confident that isn't the case in my data (though quasi-complete separation could exist; how can I test to see if that's the case?). If I remove some variables, the "did not converge" error might go away. But that's not always what happens.  I tried using the same variables in a bayesglm function and got the same errors.  What steps would you take to figure out exactly what's going on here? How do you figure out which variables are causing the problems? What makes a spell being cast considered to be a {class} spell? My understanding is that when a spell is known or prepared via one of your class features, or if you cast it via a class feature, it's considered a "class spell" (sorcerer spell, cleric spell, etc.) for you. If you cast it via some method outside your class (items, etc.), it isn't considered a spell from your class.  For clarity, some class features care about whether or not a spell is a 'class' spell (emphasis mine):    Wild Magic Surge for Wild Magic sorcerers can only trigger "[...] immediately after you cast a sorcerer spell [...]". Overchannel for School of Evocation wizards can only be used "when you cast a wizard spell [...]" Empowered Evocation for School of Evocation wizards can also only be used on "[...] any wizard evocation spell you cast". Rod of the pact keeper gives a bonus "[...] to the saving throw DCs of your warlock spells".   Contrast with a feature like Blessed Healer for Life Domain clerics that just use the language of "When you cast a spell [...]", and you'll see why I believe there's an important distinction as to whether or not a spell instance is a 'class' spell.  However, comments on  made me question where my understanding of what makes a spell instance a 'class' spell comes from, and I'm not sure of a concise spot that explains it. What are the rules that govern what is or is not considered a class spell when cast?   Of particular concern is whether or not a spell is, in all instances, a class spell once you've obtained it from your class. For example, if you were a wizard that had magic missile both prepared and in your spellbook, would any instance of magic missile you cast be considered a wizard spell, even if it was cast by way of, say, a wand of magic missile? Why does shell Command Substitution gobble up a trailing newline char? As per the following example, and as in  In bash, where has the trailing newline char gone?, I want to know "why" it happens    x="$(echo -ne "a\nb\n")" ; echo -n "$x" | xxd -p  # Output is: 610a62  # The trailing newline from the 'echo' command #   has been "deleted" by Command Substitution   I assume there must be some very significant reason for a shell action, namely Command Substitution, to actually delete some data from the command output it is substituting... but I can't get my head around this one, as it seems to be the antithesis of what it is supposed to do.. ie. to pass the output of a command back into the script process... Holding back one character seems weird to me, but I suppose there is a sensible reason for it...  I'm keen to find out what that reason is... How do I programmatically set the docstring? Let $f \in C [a,b]$ such that $\forall x\exists y$ such that $|f(y)| \leq \frac{1}{2}|f(x)|$. Prove that $\exists c\in [a,b]$ such that $f(c) = 0$. I understand there has been so much on this topic but I am still confused. I get that if the person is the subject it is who and anything else is whom. However, I'm really struggling to work out this rule for the following sentence:     The scope of which his account of morality applies to is therefore restricted to those whom/who the ‘notion of justification to a being of that kind makes sense.’   Should it be who or whom? I can't work out the subject and object. Considering an ideal case(neglecting drag of air, damping etc.), a pendulum follows SHM if the angular displacement is small (upto 10 degrees). But, for large angular displacement(more than 10 degree), it does not follow SHM. Why? What force cause the pendulum not to follow SHM? How can I launch a GameObject at a target if I am given everything except for its launch angle? I am trying to launch an object at a target, given its position, its target position, the launch speed, and the gravity.  I am following this formula from :  $$ \theta = arctan \bigg( \frac{v^2 \pm \sqrt{v^4-g(gx^2 + 2yv^2)}}{gx} \bigg) $$  I have simplified the code to the best of my ability, but I still cannot consistently hit the target.  I am only considering the taller trajectory, of the two available from the +- choice in the formula.  Does anyone know what I am doing wrong?  using UnityEngine;  public class Launcher : MonoBehaviour {     public float speed = 10.0f;      void Start()     {         Launch(GameObject.Find("Target").transform);     }      public void Launch(Transform target)     {         float angle = GetAngle(transform.position, target.position, speed, -Physics2D.gravity.y);         var forceToAdd = new Vector2(Mathf.Cos(angle), Mathf.Sin(angle)) * speed;         GetComponent&lt;Rigidbody2D&gt;().AddForce(forceToAdd, ForceMode2D.Impulse);     }      private float GetAngle(Vector2 origin, Vector2 destination, float speed, float gravity)     {         float angle = 0.0f;          //Labeling variables to match formula         float x = Mathf.Abs(destination.x - origin.x);         float y = Mathf.Abs(destination.y - origin.y);         float v = speed;         float g = gravity;          //Formula seen above         float valueToBeSquareRooted = Mathf.Pow(v, 4) - g * (g * Mathf.Pow(x, 2) + 2 * y * Mathf.Pow(v, 2));         if (valueToBeSquareRooted &gt;= 0)         {             angle = Mathf.Atan((Mathf.Pow(v, 2) + Mathf.Sqrt(valueToBeSquareRooted)) / g * x);         }         else         {             //Destination is out of range         }          return angle;     } } Unable to change payment information to NONE in iOS Appstore I know that if you held an infrared remote in front of a digital camera, it'll flash a blue/purplish light when you press the buttons. Why?    (Image by  .)