OSX zsh - Why do binaries only execute with the full path? I'm just writing some small C scripts and testing them. Why dose  ~ Desktop: gcc test.c -o test ; /Users/xx/Desktop/test ;   work just fine while   ~ Desktop: gcc test.c -o test ; test ;   dose not work? Why dose OSX/ZSH need the full path to execute the binary?
Mac OS X 10.6 executable not found without full path I just installed Apache via MacPorts. It seems that my Mac was absolutely confused about which version of the Apache executables to run.  After moving the Apache executables that ship with the Mac to a directory that is not listed in the PATH variable, trying to run the httpd built by MacPorts fails even though the correct directory (/opt/local/apache2/bin) is listed in the PATH variable.  If I navigate to the directory /opt/local/apache2/bin and type the command httpd I still get the error message     -bash: httpd: command not found   If I type the command with the full path /opt/local/apache2/bin/httpd it works fine.  I've run the command alias to see if something was clashing but the only thing listed is:  alias wget='curl -O'   How do I find what is intercepting the command and preventing the executable being found in the directory, even when I'm inside the same directory?  By the way, the httpd file is executable:  -rwxr-xr-x  1 root      admin  442496  9 May  2012 httpd
How can I find the following limit :$$\lim_{n\to\infty}\left(1-\frac{1}{3}\right)^2\left(1-\frac{1}{6}\right)^2\left(1-\frac{1}{10}\right)^2\cdots\left(1-\frac{1}{\frac{n(n+1)}{2}}\right)^2$$There are four options $(a)\frac1{3}(b)\frac1{9}(c)\frac1{81}(d)0$ Thanks! Some of you might insist that it was not a murder, as we know that a rebounding spell had hit Ariana, as shown in .  However, a death in such a well known family would not go uninvestigated, I presume. Were the Dumbledore brothers investigated? How did they get away with their sister suddenly dropping dead?  I'd think that Ministry of Magic has means to recognize a death caused by magical means. That's how we know that Tom Riddle Snr. was killed by Avada Kedavra. So Ariana's failing health might be a poor excuse. Confusion with floating point numbers How to prevent "Delhi Belly"? Why are airline passengers asked to lift up window shades during takeoff and landing? I have always wondered why the windows shades have to be raised during take off and landing. I can't think of any safety issues by having a closed window. Variance of the distribution of difference scores What does this triangle/diamond schematic symbol represent? How does SQL Server handle logins when the user is a part of multiple groups with various privileges? I'm trying to wrap my head around how SQL Server decides to grant certain rights based on a users login privileges.  If a user is part of a group "READ ONLY" which has access to DB1, but they are also a part of a group "SysAdmin" which has full db owner rights to the same DB1, which rights are they given when they log in?  On a similar note. What if they are part of a group but also have a standalone account with other middle of the road privileges? I've tried everything I can think of. Resetting the router, changing the channel number and band.   The internet connection is fine, and then just hangs for a minute or 2, then returns to normal.   The wifi icon remains connected, and I have the latest 10.10.4 update installed. At first I thought it was a DNS bug with Yosemite, and have played with the settings such as changing DNS provider, changing the IPV6 to IPV4 only etc.  Driving me nuts. Has anyone had a similar problem? I've checked the surroundings with wifi scanners and have chosen the best channel available.     One thing I have noticed, it seems a lot more reliable on 5GHz as opposed to 2.4Ghz It seems to affect my Macbook Pro Retina 13in Early 2015 a lot more than the other devices on the network. I'm using a Virginmedia  1. I would like to take a picture of a street during the day to depict how much traffic and cars there are on the street.  Is there anyway to do this with a long exposure photograph?  I have a Nikon D90 and I set the f stop down to 1/16 (the lowest of my lens) and set the time to 2 seconds. Doing this, the exposure is almost saturated when taken around 5pm with the sun setting behind a tree. Doing this, the cars passing by were very hard to make out against the stationary background, being visible as a blur in the color of the car.  Perhaps this is not possible and I should just do this at night where the cars lights are much brighter than the background.  Please suggest how else I might depict the traffic in a photograph?  Are daytime long exposure photographs even possible? .NET How to check if path is a file and not a directory? I have a path and I need to determine if it is a directory or file.    Is this the best way to determine if the path is a file?  string file = @"C:\Test\foo.txt";  bool isFile = !System.IO.Directory.Exists(file) &amp;&amp;                           System.IO.File.Exists(file);   For a directory I would reverse the logic.  string directory = @"C:\Test";  bool isDirectory = System.IO.Directory.Exists(directory) &amp;&amp;                              !System.IO.File.Exists(directory);   If both don't exists that then I won't go do either branch.  So assume they both do exists. Every Function in a Finite Field is a Polynomial Function From a bank of past master's exams I am going through:     Let $F$ be a finite field. Show that any function from $F$ to $F$ is a polynomial function.   I know that finite fields are fields of $p$ elements for $p$ prime [EDIT: It's actually $p^n$ for $p$ prime; see comment below]. Since I have $p$ choices for the $p$ elements to map to, then I have $p^p$ distinct functions. I think every function can be written in the form $f(x) = a_{p-1}x^{p-1} + \dots + a_0x^0$. For then given the values $f(0), f(1), \ldots f(p-1)$, I can solve for the coefficents by the linear system of equations  $$ a_0 + \sum_{i=1}^{p-1} n^i a_i = f(n).$$  This then gives me a $p-1 \times p-1$ square matrix over the field $\mathbb{F}_p$:  $$\left( \begin{array}{ccccc} 1&amp; 0 &amp; 0 &amp; \ldots &amp; 0 \\ 1&amp; 1 &amp; 1 &amp; \dots &amp; 1 \\ 1&amp; 2 &amp; 4 &amp; \dots &amp; 2^{p-1} \\ \vdots &amp; \vdots &amp; \vdots &amp; &amp; \vdots \\ 1 &amp; p-1 &amp; (p-1)^2 &amp; \dots &amp; (p-1)^{p-1} \end{array} \right) \left( \begin{array}{c} a_0 \\ a_1 \\ a_2 \\ \vdots \\ a_{p-1} \end{array}\right)  = \left( \begin{array}{c} f(0) \\ f(1) \\ f(2) \\ \vdots \\ f(p-1) \end{array} \right)$$  If I can show this matrix is invertible, then I can always find the $a_i$. But I am a bit stumped on how to show this (partially because I don't think I've ever done linear algebra in a vector space over a finite field). It does not seem easy to show linear independence, or nonzero determinant, or full row rank.    Alternatively (I just thought of this), can I show this is true by arguing that the map between the two sets (the set of polynomials of degree $p-1$; and the set of functions $F \to F$) is injective, and that it must be a bijection because the sets have the same cardinality $p^p$? First off, here is some code:  int main()  {     int days[] = {1,2,3,4,5};     int *ptr = days;     printf("%u\n", sizeof(days));     printf("%u\n", sizeof(ptr));      return 0; }   Is there a way to find out the size of the array that ptr is pointing to (instead of just giving its size, which is four bytes on a 32-bit system)? In the early '80s, I read a story about a Terran man on another planet, where the natives develop skin lesions and eventually die, but are happy, as they become part of the planet they live on. I remember that the protagonist is not developing the lesions, because he hates the planet. Once he starts loving the planet, he starts having the lesions as well. In this story, the planet is "alive".  I have read about "" and "". They do not match my memory. Thank you. Does the Polyjuice Potion Dark Mark work? I was just reading Harry Potter and the Deathly Hallows, and I was wondering, when Hermione Granger changed into Bellatrix Lestrange, she should've obtained the Dark Mark, temporarily.  Now, my question is: would the Dark Mark work if pressed? Where do I ask where to ask? If I have a specific question I want to ask about, but I don't know which Stack Exchange site would be on topic for asking that question, where can I ask where to ask that question?  Is there any generic place where we can ask for advice? Is it here?  This is not about a specific question but in general.  For example: "Where should I ask for advice about fishing?", or if I need to know where I should ask "What would be the best fishing rod to fish for salmon?" (regardless of how good/bad these examples are) What license to use while putting papers on the Arxiv? I am new to this and not sure what to make of all the options available. I am interested in putting a machine-learning-related preprint, which will potentially be submitted to places like NIPS/ICLR/ICML in the future.   arXiv.org perpetual, non-exclusive license to distribute this article (Minimal rights required by arXiv.org)  Creative Commons Attribution license (CC BY 4.0)  Creative Commons Attribution-ShareAlike license (CC BY-SA 4.0)  Creative Commons Attribution-Noncommercial-ShareAlike license (CC BY-NC-SA 4.0)  Creative Commons Public Domain Declaration (CC0 1.0) It's often the case that I want to change name servers because my site is messed up.  Well, it takes a very long time for the name server to propagate.  Is there something in DNS, or registrar or anything I can do to speed that up.  Flushing my dns server using  and it rarely works indicates that the water pipes should bonded to the electrical ground even if a grounding rod is used. How would one normally tell if that is the case? Is that bonding required to be accessible, or can it be hidden behind walls or buried? Where in the water system would it normally be bonded (e.g., before the main water shutoff, after, at the hot water tank)?  I recently had my electrical panel relocated and replaced, and don't recall seeing anything running from the panel to a water pipe - in the old panel or new. The electrician put in an intersystem bonding bridge, so the new ground rod, ground from the panel, and ground from the cable service are connected to it. I suppose that's where the bond from the water pipe would go? How to create a site in a sitecollection on a remote SPServer using C#