This is pretty simple but I don't know how to describe it. There's a door that if left open half way it opens all the way by itself. I'm not sure if it's on an angle and gravity is doing it. How do I make it so the door stays where it is and doesn't open all the way? It's on 3 hinges and is on the inside of the building.
I have a normal door, and left to its own devices it will simply rest about 20-30 degrees. It won't swing shut on its own, nor stay open on its own. It hangs a bit in the middle. Convenient enough to catch you elbow when you're not looking.  I'd like the door to stay put wherever we leave it.  I've heard idea such as slipping cardboard in to the hinge to rebalance the door, etc. but no guidelines as to the thickness of that cardboard, or which hinge to change to move it in which direction.  I would hope you can appreciate how I'd rather not make this a task of trial and error and continually removing the hinge and putting it back on, etc.  I've also heard something about lightly bending one of the hinge pins, but not sure how I should go about that, or "how much" to bend it.  So, I'm looking for some tips on how to fix this (and other) door.
Boot error > no such device: grub rescue After an installation of Ubuntu 12.04, erasing an old partition with Ubuntu 10.10, I can't get grub to load. I can't access my Windows 7 partition either  I get the message:  &gt; error: no such device: 58ABF29C...   grub rescue&gt;   I suppose my master boot record got erased/corrupted. How can I check and fix this? Why does this cloth go down past the top surface of the cube? I was following a , and the presenter said that he did not change the default options other than enabling self-collision and increasing the collision object's friction from 5 to 10. His looks like the first image below, but when I tried that, the cloth goes down past the top surface and stops at the bottom surface (second and third images below). Why is it so?   I had a previous problem with cloth, and it was due to the objects' small size. This time, I made sure that both the cloth and the cube are large enough. (Cloth=7.68*8.22*1.99m, cube = 7.68*7.68*0.897m)  The project file can be . How is Angular Momentum Conserved when Mass is Released? I am not a physicist (math/comp-sci) but I understand that Angular Momentum is supposed to be conserved.  I find this confusing because there seems to be many simple, common cases where a restrained, revolving body, when released seems to lose it's angular momentum.  For example, let's say that a hammer thrower is revolving a 10kg hammer around herself at a 1 meter distance from their combined center of mass every second.  Taking the hammer as a point-mass, then before release, the hammer and the thrower each have an angular momentum of      $l\omega = (mr^2)*(2\Pi) = (10*1*1)*(2*3.14..) =~ 62.8 kg\text{-}m^2/s$   Now, after the hammer is released, the thrower still has her same angular momentum (also 62.8), but the hammer no longer seems to have any.  Yes, I know that the hammer is still rotating (spinning) as it did when it was revolving around the thrower, so that angular momentum seems to be conserved, but the angular momentum from revolution (orbiting) seems to be gone.  AFAIK, it's not transferred to it's spin angular momentum (observation seems to bear this out).  Nor is it transferred to the thrower.  Besides having no mechanism for this (she let go of it), if it did, we would have noticed hammer throwers being knocked over by having their angular momentum suddenly doubled.  So where does it go?  Or is it not actually conserved in this case? Toggle wireframe mode with hotkey How do I toggle in and out of wireframe mode with my keyboard? Is there a hotkey for this?  I'm a beginner (obviously). I thought I could find this in the "view" menu, but it either doesn't exist or I have horrendous eyesight. Thanks! Calculating optimal number of bins in a histogram I'm interested in finding as optimal of a method as I can for determining how many bins I should use in a histogram. My data should range from 30 to 350 objects at most, and in particular I'm trying to apply thresholding (like Otsu's method) where "good" objects, which I should have fewer of and should be more spread out, are separated from "bad" objects, which should be more dense in value. A concrete value would have a score of 1-10 for each object. I'd had 5-10 objects with scores 6-10, and 20-25 objects with scores 1-4. I'd like to find a histogram binning pattern that generally allows something like Otsu's method to threshold off the low scoring objects. However, in the implementation of Otsu's I've seen, the bin size was 256, and often I have many fewer data points that 256, which to me suggests that 256 is not a good bin number. With so few data, what approaches should I take to calculating the number of bins to use? Why does Math.Floor(Double) return a value of type Double? Size of files in Windows OS. (It's KB or kB?) Prove that the ideal $(X_1-a_1,...,X_n-a_n)$ is maximal in $K[X_1,\dots,X_n]$ Let $K$ be a field, and $a_1,\dots,a_n \in K$. Prove that the ideal $$(X_1-a_1,\dots,X_n-a_n)$$ is maximal in $K[X_1,\dots,X_n]$.   I tried proving that the only elements outside the ideal are the invertibles of $K$ (I should still prove that this implies maximality, but it shouldn't be too difficult).  Is there a better strategy, or another stategy? When to choose checked and unchecked exceptions In Java (or any other language with checked exceptions), when creating your own exception class, how do you decide whether it should be checked or unchecked?  My instinct is to say that a checked exception would be called for in cases where the caller might be able to recover in some productive way, where as an unchecked exception would be more for unrecoverable cases, but I'd be interested in other's thoughts. Why isn't Harry Potter punished for using magic outside of Hogwarts in Prisoner of Azkaban? Dimensions of Scale (Gamma) and Offset (Beta) in Batch Norm While implementing Batch Normalization for a particular layer 'L' with 'n' hidden neurons/units in a Neural Network, we first normalize the Activation values of that layer using their respective Mean and Standard Deviation, and then apply the Scaling and Offset factor as shown:     X-norm = (X - mu)/sd X' = (Y * X-norm) + B       where    mu = mean of X and it is a (n,1) vector          sd = standard deviation of X and it is also a (n,1) vector         X = Activation values of layer 'L' with dimension (n,m) if mini-batch    size = m   X-norm = normalized X with dimension (n,m)   Y = Gamma / Scaling factor   B = Beta / Offset factor   Now my question is, what are the dimensions of Gamma and Beta ? Are they (n,1) vectors or are they (n,m) matrices ? My intuition says that since they somewhat are analogous to the Mean and Standard Deviation, they should be (n,1) vectors. Update Eclipse with Android development tools v. 23 Let $\{a_n\}$ be an unbounded, strictly increasing sequence of positive real numbers and let $x_k=\frac{a_{k+1}-a_{k}}{a_{k+1}}$. Which of the following statements is/are correct? (CSIR NET December 2014)         For all $n\geq m, \sum\limits^{n}_{k=m}x_k&gt;1-\bf{\frac{a_m}{a_n}}$   There exist $n\geq m, \sum\limits^{n}_{k=m}x_k&gt;\frac{1}{2}$      My attempt:  Analysing question in light of $a_k=k\implies x_k=\frac{k+1-k}{k+1}=\frac1{k+1}$, I feel both are correct, I doubt if  I can generalise the result in light of this one example.   Any way to prove that this true for general case?    Note: Please do not confuse  with my question. The first two options are different, I've marked the difference in bold. What is the simplest organism that was observed to learn: change its behavior permanently in response to some event/stimuli in a way that this change persists even if the event does not happen again? Recovering data from a phone stuck in restore mode I have an iphone 4 that is stuck in restore mode after trying to update to ios 6 wirelessly.  Unfortunately, I do not have a recent itunes backup of this phone.  Is there any way to recover my photos from this device before I try to restore it?  Will restoring it wipe all the data on the phone? Copying prod multi-site installation to dev multi-site installation I am attempting to upgrade my Drupal 8.9.2 multi-site installation to D9. I was hoping to work this all out on a development installation, that is located in a subdirectory of my home directory on my NameCheap Shared Hosting plan. When I first installed this installation, I did so using the tarball method from years ago. I then followed the instructions given here (). I was able to get the current running prod version converted to use composer with out an issue. Before I go and start messing with the files, and attempting to upgrade to D9 through composer on a prod installation, I wanted to copy these files over to another installation where I can use it as a sandbox. To do this I:  copied the files on my server to a new directory made clone databases for the new installation truncated all the cache tables in the cloned DB changed all the database settings in the settings files to point to the cloned databases  I've done this before without any issues, and now I seem to be getting a WSOD error on all the sites running from the new installation. The error I'm getting is  PHP Fatal error:  Uncaught Error: Class 'Drupal\Core\Cache\DatabaseBackend' not found in ~/{new installation dir}/public_html/index.php:16.  If anyone has any thoughts what's going on I am all ears. Thank you in advance How to clone/copy all file/directory attributes onto different file/directory? I want to copy the attributes (ownership, group, ACL, extended attributes, etc.) of one directory to another but not the directory contents itself.  This does not work:  cp -v --attributes-only A B cp: omitting directory `A'              Note: It does not have to be cp. I understand that a black hole bends the fabric of space time to a point that no object can escape.   I understand that light travels in a straight line along spacetime unless distorted by gravity. If spacetime is being curved by gravity then light should follow that bend in spacetime.  In Newton's Law of Universal Gravitation, the mass of both objects must be entered, but photon has no mass, why should a massless photon  be affected by gravity in by Newton's equations?  What am I missing? In the discussion from a question I asked several days ago (), someone suggested that I use general.runalg() instead of processing.runalg() for running QGIS algorithms.    I've now used both, and haven't noticed a difference in either performance or syntax between them.  I'm just wondering what sort of differences there are between these two methods, and which one I should be using. I'm working on this problem from Elementary Analysis by Ross which is intuitive when sketched but keeps stymieing me when I try to write it out.  Let $f$ be a continuous function on $[a,b] \subset \mathbb{R}$. Define $f^\star (x)$ as:  $$ f^\star(x) = \sup \{f(y)\mid a \leq y \leq x \} $$ Prove that $f^\star$ is a continuous increasing function on $[a,b]$.  Things I've figured out: (these are mostly trivial)   $f$ is uniformly continuous on $[a,b]$. Since $[a,b]$ is closed and bounded there exists some $c \in [a,b]$ such that $f(c) \geq f(x)\ \forall x \in [a,b]$. (In words: the supremum is actually attained.) If $c \in [a,b]$ is as above, then $f^\star$ is constant (and hence continuous) on $[c,b]$ (which is possibly a singleton).   This seems completely obvious when you actually draw a continuous function but translating that to a formal proof eludes me...