What is the standard deviation and mean of the reciprocal of normal distribution in terms of the standard deviation and mean of the normal distribution?
My random variable $X$ is normally distributed with mean $b$ and variance $p$. I defined a new RV, $Y$, such that $Y=1/X$. Does anyone know how to find the mean of $Y$ and $Y^2$?
Showing that $\int\limits_{-a}^a \frac{f(x)}{1+e^{x}} \mathrm dx = \int\limits_0^a f(x) \mathrm dx$, when $f$ is even How to copy some, but not all files? So, you can use the * as a wild card for all files when using cp within context of a directory.  Is there a way to copy all files except x file? I'm fairly new to blender and not a graphics person by any stretch of the imagination. I've been having some success though modelling semi-reflective glass for a project I wish to build (physically) and I'm wondering if it is possible to model the effects of a lens. The lens I wish to model is a double-convex type. It has a diameter of 120mm and a focal-length of 301mm. Is this something that can be modelled in blender and if so, how? I'd like to be able to position the camera close to this lens and reproduce the magnifying effects of the lens on the scene behind the lens as well as depth-of-field effects.  Thanks a lot. Prove that the minimum number of cycles is $m-n+1$ The question I have is:   Prove that the minimum number of cycles is $m-n+1$ in a connected graph. Where one cycle is a path that starts that begins and ends at the same vertex. Where $m$ is edges and $n$ is the vertices.   I have no idea where to start. A few hints would be appreciated. Please do not provide me with the answer. Topical example:  'There was a scuffle outside the local pub. There appears to be no connection with religious extremists.'  ...but now you're wondering if there was. It's a nasty tactic used to raise fear and doubt - deliberately calling attention to something by explicitly denying it.  What's the term for this? Solve $f(x)f(2x^2) = f(2x^3+x)$ Blender image output is greyish and not white I already searched the internet but could not find a solution to this. Maybe it is the same question as  but there was no answer.  I want to render a video with tracking, but the output "loses" color information and gets kind of greyish. I first thought that it is related to the renderer, but it happens in Cycles and Eevee. Therefore i made a sample image, added it to the image sequence editor and rendered it as 1 frame. Resulting in the same problem.  I placed the original image beside blenders output so that you can see the difference. The only idea I came up with is that something with the lighting is not correct but I can't find a setting for that.  I am using Blender 2.80 with the default settings. Only set the output resolution to match the input resolution. Execute bash commands over SSH while staying in interactive mode afterwards Probably it is a weird thing I would like to achieve but: I would like to SSH to a remote host and then execute some bash commands like "alias" automatically to use them afterwards in an interactive mode. The remote host does not allow the personal environment.    Is this possible? Would "expect" do it? Or is there any other way to achieve this? Basically I would like to have my bashrc without modifying any files on the remote host. Do I need a UK visa? How and where to apply? I live in Germany since May 2013 as a spouse of German citizen. In Nov 2015 we divorced and I have German residence permit till Jan 2018. We have a son in this marriage and legally I have the right to live in Germany indefinitely. I would like to visit my brother and sister who are British citizens living in UK. What is the visa procedure for me to travel to UK for a week.  Do I need a visa to enter UK ? where do I use Database. Methods? Word to describe someone who goes to all the events in town! ConcurrentModificationException Woes I have a bunch of external and internal HDDs that I use on a Linux system. I only have Linux systems, so using a Linux file-system would only make sense, right? However I'm currently using NTFS everywhere, because it gives me the most usable space out of HDDs.  I would like to switch to Linux file-systems now though, mostly because of permissions and compability (e.g. I can't get my LUKS encrypted NTFS partition to resize under Linux, keeps telling me to chkdsk under Windows).  However when I formatted those HDDs I tried out a bunch of different filesystems and every Linux filesystem, even ext2 which as far as I know has no journaling, used a lot of space for itself. I don't recall exact values, but it was over 100GB that NTFS got me more on a 2TB HDD, which is a lot.  So my question is: Is there a way to make ext-filesystems use less space for themselves? Or is there another filesystem (I've tried ext2, ext3, ext4, NTFS and vfat - None of them came even close to the usable space NTFS offered me) with perfect Linux support and great usable space?  I'd love to hear about how and why filesystems (especially ext2 which has no journaling) use that much more space than NTFS and I don't know where else to ask. I'd mostly prefer a way to use ext4 without journaling and anything else that uses up this much space, if that's possible. Does a fighter's Action Surge trigger Extra Attack? Context  A player in my game will play a fighter with a greatsword. At 5th level he has Extra Attack and the option to use Action Surge. PHB p.72 states:     Action Surge. Starting at 2nd level, you can push yourself beyond your normal limits for a moment. On your turn, you can take one   additional action on top of your regular action and a possible bonus   action.      Once you use this feature, you must finish a short or long rest before   you can use it again. Starting at 17th level, you can use it twice   before a rest, but only once on the same turn.        Extra Attack. Beginning at 5th level, you can attack twice, instead of once,   whenever you take the Attack action on your turn.       The number of attacks increases to three when you reach 11th level in   this class and to four when you reach 20th level in this class.   Confusion  The questions and answers that I find on here deal with multi-classing or Two Weapon fighting specifically, which don't really give a clear yes or no on my question.  The way I read these two features is that when a fighter takes an Attack action, he gets the Extra Attack. After using Action Surge he gets the opportunity to take another Attack action, and with that another Extra Attack. This results in four attacks with the greatsword in one turn, which sounds amazing but also rather powerful. Is this correct, or am I missing something? Close Lightning Modal by clicking anywhere outside of it If $\sum_{n=1}^{\infty} a_n^{2}$ converges, then so does $\sum_{n=1}^{\infty} \frac {a_n}{n}$ Let $a_1,a_2,a_3,\ldots$ be reals. Prove that if $\sum_{n=1}^{\infty} a_n^{2}$ converges, then so does $\sum_{n=1}^{\infty} \frac {a_n}{n}$.   For this I have shown the case for when $ a_n^{2} \le\frac {|a_n|}{n}$ $\Rightarrow$ $ |a_n|\le\frac {1}{n}$ $\Rightarrow$ $\frac {|a_n|}{n} \le \frac{1}{n^{2}}$ and we know that $\sum_{n=1}^{\infty} \frac {1}{n^{2}}$ converges and hence $\sum_{n=1}^{\infty}\frac {a_n}{n}$ converges by the comparison test. Now considering $ a_n^{2} \ge\frac {|a_n|}{n}$ $\Rightarrow$ $\frac {|a_n|}{n} \le a_n^{2}$ $\rightarrow$ combining the two cases for any n we have: $\frac {|a_n|}{n}\le\frac{1}{n^{2}}+a_n^{2}$ Hence using the comparion test again we know that $\sum_{n=1}^{\infty} a_n^{2}$ converges and $\sum_{n=1}^{\infty} \frac {1}{n^{2}}$ converges hence the sum converges so we can conclude that $\sum_{n=1}^{\infty} \frac {a_n}{n}$ is absoluetly convergent $\Rightarrow$ convergent.  Not to sure if this is correct, any help would be much appreciated, many thanks. In Harry Potter and the Prisoner of Azkaban, Harry sneaks into The Three Broomsticks and overhears Madam Rosmerta, the Minister for Magic, and several Hogwarts teachers discuss his parents' death and the fact that the Potters were under the protection of the Fidelius Charm. Professor Flitwick explains the charm:     ‘An immensely complex spell,’ he said squeakily, ‘involving the magical concealment of a secret inside a single, living soul. The information is hidden inside the chosen person, or Secret-Keeper, and is henceforth impossible to find – unless, of course, the Secret-Keeper chooses to divulge it. As long as the Secret-Keeper refused to speak, You-Know-Who could search the village where Lily and James were staying for years and never find them, not even if he had his nose pressed against their sitting-room window!’   Prisoner of Azkaban - pages 152-153 - Bloomsbury - chapter 10, The Marauders Map   In Harry Potter and the Deathly Hallows, once Ron returns to Harry and Hermione after his and Harry's fight weeks earlier, he tells Harry and Hermione about the Taboo:     ‘NO!’ roared Ron, causing Harry to jump into the hedge and Hermione (nose buried in a book at the tent entrance) to scowl over at them. ‘Sorry,’ said Ron, wrenching Harry back out of the brambles, ‘but the name’s been jinxed, Harry, that’s how they track people! Using his name breaks protective enchantments, it causes some kind of magical disturbance – it’s how they found us in Tottenham Court Road!’   ‘Because we used his name?’   ‘Exactly! You’ve got to give them credit, it makes sense. It was only people who were serious about standing up to him, like Dumbledore, who ever dared use it. Now they’ve put a Taboo on it, anyone who says it is trackable – quick and easy way to find Order members! They nearly got Kingsley –’   Deathly Hallows - page 316 - Bloomsbury - chapter 20, Xenophilius Lovegood   So in hindsight the trio understands that it was the Taboo that caused the Death Eaters to find them at Tottenham Court Road, and then later, of course, they're caught by Snatchers because Harry says "Voldemort" out loud. However, the trio says "Voldemort" numerous times while they're staying at Grimmauld Place and Death Eaters appear and stake the place out (granted, it could be that the Death Eaters simply knew that Harry had inherited Grimmauld Place from Sirius after the Ministry examined Sirius's will). They cannot get inside the house, though. I'm completely unclear as to the status of Grimmauld Place and the Fidelius Charm -- the house was under the charm, but the Secret Keeper (Dumbledore) had died. Nevertheless, like eleventy-one people were privy to the secret by the time of Dumbledore's death, and I have never found a satisfactory answer (to me) to exactly how the Fidelius Charm works.   Would Voldemort's Taboo spell be able to trump the Fidelius Charm?  &#9733; I'm looking for a canon-based answer (Harry Potter novels, the three supplemental books, JKR interviews, and Pottermore) and do not prefer an answer from the HP Wikia or the Wikipedia. What is a combo update and how is it different than the regular update? Compact operators on an infinite dimensional Banach space cannot be surjective I am reading a book about functional analysis and have a question:      Let $X$ be a infinite-dimensional Banach-space and $A:X \rightarrow X$ a compact operator. How can one show that $A$ can not be surjective? What are the highest DC and AC voltages or currents that can be considered as safe?