Return derived object through base class reference parameter
What is object slicing?
have lived vs have been living Prove that : $a_n>0$, Then, $\sum_{n=1}^\infty a_n$ converges iff $\sum_{n=1}^\infty \sin(a_n)$ converges. I am given the problem: Let $a_n&gt;0$, prove $\sum_{n=1}^\infty a_n$ converges if and only if $\sum_{n=1}^\infty \sin(a_n)$ converges.  We have this problem in a homework, and I don't believe it can be true. The statement being biconditional implies that when $\sum_{n=1}^{\infty} \sin(a_n)$ converges, so too does $\sum_{n=1}^\infty a_n$, but if we take $a_n=\pi n$ or even $a_n=\pi$, then $\sum_{n=1}^\infty \sin(a_n)$ converges while $\sum_{n=1}^\infty a_n$ diverges. Is my thinking incorrect? Can I disable pinch to show all open tabs in Safari? Ubuntu 16.04 has been hanging on me ~1x per day.  This happens when I am in the middle of web browsing or using a desktop application, not when booting.  When it does, the mouse pointer will still move freely, but clicking or keystrokes have no effect on my system until I do a hard reboot.  What is the best way for me to debug this?  Here is some information:  selah@selah-Precision-Tower-5810:~$ uname -a Linux selah-Precision-Tower-5810 4.4.0-59-generic #80-Ubuntu SMP Fri Jan 6 17:47:47 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux   Also, in case it is relevant, I have a "very big" monitor, a Dell 42" at 3840x2160 resolution.  selah@selah-Precision-Tower-5810:~$ lspci | grep VGA 03:00.0 VGA compatible controller: NVIDIA Corporation GM107GL [Quadro K2200] (rev a2)     UPDATE:  Following Artyom's advice I found the following message in my error logs:   Apr 27 09:47:25 selah-Precision-Tower-5810 kernel: nouveau 0000:03:00.0: fifo: SCHED_ERROR 0a [CTXSW_TIMEOUT] Apr 27 09:47:29 selah-Precision-Tower-5810 kernel: nouveau 0000:03:00.0: fifo: SCHED_ERROR 0a [CTXSW_TIMEOUT] Apr 27 09:47:33 selah-Precision-Tower-5810 kernel: nouveau 0000:03:00.0: fifo: SCHED_ERROR 0a [CTXSW_TIMEOUT]   Which has let me to this bug which describes similar behavior: Are mixed geometry types allowed in shapefiles? Does the shapefile support mixed geometry types (ie. point and polygon all in the same file)? Can't do comparison on PageReference In my page constructor I call a method isFirstPageLoaded, to  check if the loaded page is the first page of the wizard.   private final PageReference FIRSTPAGE = Page.Maintenance_Lock_1;   private void isFirstPageLoaded() {          if(ApexPages.currentPage()!=this.FIRSTPAGE) {              throw new MaintenanceLockException(this.FIRSTPAGE + ' --- ' + ApexPages.currentPage());          }      }   The problem is: Even if I open the first page of the wizard, the exception is thrown. How can I compare two PageReferences? I would like to avoid to parse the URLs and remove parameters etc... How to read the content of a file to a string in C? Is it a good practice to show a sign-up or registration form as seperate parts rather than in one go? I am designing a registration form for a site with multiple sets of information required from the user. I have categorized the data fields into relevant groups. Now should I present the form sections in one go or follow a wizard-like approach? What things should I keep in mind while deciding on this? Complement of maximal multiplicative set is a prime ideal In-universe explanation for single line of planetary entry/departure in Star Wars Show discontinuity of $\frac{xy}{x^2+y^2}$ From the  article on Wikipedia, the following with regard to the Coriolis Effect on a rotating sphere:     By setting vn = 0, it can be seen immediately that (for positive φ and ω) a movement due east results in an acceleration due south. Similarly, setting ve = 0, it is seen that a movement due north results in an acceleration due east. In general, observed horizontally, looking along the direction of the movement causing the acceleration, the acceleration always is turned 90° to the right and of the same size regardless of the horizontal orientation.   My intuitive (but possibly incorrect) understanding is that if there are two points, Point A and Point B, at different latitudes in the Northern hemisphere, the Eastward velocities of these points are different because they are at different distances from the Earth's axis of rotation, and this causes the Coriolis effect for a rotating sphere.  If a projectile is fired due North from Point A near the Equator towards Point B near the North Pole, the projectile will start off with the higher Eastward velocity of Point A, and will land to the East of Point B, which is moving East at a slower velocity than the projectile.  Firstly, is that correct?  If that IS correct, that brings me to the quote off Wikipedia. The quote implies that, if a projectile is fired due East, it will experience a Coriolis force to the South. My intuitive explanation based on differences in velocities between origin and destination does not account for a Southwards movement at all, since the Point A and Point B velocities are identical if the points are on the same latitude.  What am I missing? Would a projectile fired due East or due West experience any North or South drift caused by the Coriolis effect (or anything else for that matter)?  Why? Why do diamonds shine? When editor does not respond to the request for withdrawal I submitted a manuscript to a journal, but due to some issue with that I asked the Editor-in-Chief and Associate Editor to withdraw the manuscript from further consideration. Despite several emails, they are not still responding me nor ended the process.  Now, what should I do? Can I submit the manuscript to another journal? How to disable auto brightening LCD "In a while" vs. "for a while" 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; Is there a case where including the same header twice is actually helpful? One of the new features in SQL Server 2012 codenamed Denali is the   I know a good bit about regular old row-store indexes, like the b-tree structure, differences in storage between the leaf level and b-tree pages, affects of included fields, optimizing to use them, order of keys, etc.  I'm having difficulty getting any good info on the internals of a columnstore index.     How is it structured? Is there a b-tree?  Some other structure in place? How is data organized? What sorts of specific operators are best suited to use it? Any other anti-patterns to be avoided when using them?   A lot of what I can find out about them are basically the exact opposite of a "normal" index, i.e. no ordering of keys, no included fields, nonclustered ONLY.  Any insights are appreciated. Some observations I made is for $\frac{a}{b}+\frac{b}{a}$, is either:   the denominator has to be one, the numerator has to be a multiple of the denominator or  the numerator and denominator have to be the same.    Obviously, with the given conditions case 3 is eliminated since  $a \neq b$.  For case 1, if $b=1$, then $a=1$ which is a contradiction to the given condition that says $a \neq b$.  For case 2, I would think of examples. For example if $b=2$ then a multiple is $4$, so $a=4$. Then we have:  $$\frac{a}{b}+\frac{b}{a}=\frac{4}{2}+\frac{2}{4}=\frac{10}{4}$$  which is not an integer, but how would i proceed to show this case for all integers.