As a beginner I tried to make a simple DC circuit with an opamp on a single supply. This is what I came up with:         &ndash; Schematic created using   I use R3 and R4 as a voltage divider to get 1V between the inputs of the opamp, and R1 and R2 in the noninverting configuration. I tested this circuit in a few simulators and they show 3V at the output.  $$ Gain = 1 + \frac{R2}{R1}=1+\frac{560}{270}\approx3 $$    I built the circuit and measure 5.64V where I expected 3V. What am i doing wrong?
Simple enough question. Why not use a  in a target circuit or anyone's target circuit? What are the reasons not to use it? What might be the reasons to still choose this part?
Grep: unexpected results when searching for words in heading from man page I'm running into weird behavior when trying to grep a man page on macOS. For example, the Bash man page clearly has an occurrence of the string NAME:  $ man bash | head -5 | tail -1 NAME   And if I grep for name I do get results, but if I grep for NAME I don't:  $ man bash | grep 'NAME' $ man bash | grep NAME   I've tried other uppercase words that I know are in there, and searching for SHELL yields nothing whereas searching for BASH yields results.  What's going on here?  Update: Thanks for all the answers! I thought it worth adding the context in which I ran into this. I wanted to write a bash function to wrap man and in cases where I've tried to look up the man page for a shell builtin, jump to the relevant section of the Bash man page. There might be a better way, but here's what I've got currently:  man () {   case "$(type -t "$1")" in     builtin)       local pattern="^ *$1"        if bashdoc_match "$pattern \+[-[]"; then         command man bash | less --pattern="$pattern +[-[]"       elif bashdoc_match "$pattern\b"; then         command man bash | less --pattern="$pattern[[:&gt;:]]"       else         command man bash       fi       ;;     keyword)       command man bash | less --hilite-search --pattern='^SHELL GRAMMAR$'       ;;     *)       command man "$@"       ;;   esac }  bashdoc_match() {   command man bash | col -b | grep -l "$1" &gt; /dev/null } Displaying page construction guides Is there any way to overlay some lines and dimensions on the document so that one can see where the margins end and more easily examine the overall layout and ratios of elements on the page?  See for example, some of the illustrations of frameworks in this article on the  and this one on  (which displays dimensions). I wonder if there is any difference between mapping and a function. Somebody told me that the only difference is that mapping can be from any set to any set, but function must be from $\mathbb R$ to $\mathbb R$. But I am not ok with this answer. I need a simple way to explain the differences between mapping and function to a lay man together with some illustration (if possible).  Thanks for any help. How do I check if a list is empty? block all but a few ips with firewalld On a linux  networked machine,  i would like to restrict the set of addresses on the "public" zone  (firewalld concept), that are allowed to reach it. So the end result would be no other machine can access  any port or protocol, except those explicitly allowed, sort of a mix of     --add-rich-rule='rule family="ipv4" source not  address="192.168.56.120" drop'    --add-rich-rule='rule family="ipv4" source not  address="192.168.56.105" drop'   The problem above is that  this is not a real list, it will block everything since if its one address its blocked by not being the same as the other, generating an accidental "drop all" effect,  how would i  "unblock" a specific non contiguous set? does source accept a list of addresses? i have not see anything in my look at the docs or google result so far.     EDIT: I  just  created this:  # firewall-cmd  --zone=encrypt --list-all encrypt (active)   interfaces: eth1   sources: 192.168.56.120   services: ssh   ports: 6000/tcp   masquerade: no   forward-ports:    icmp-blocks:    rich rules:    But i can still reach port 6000 from  .123   my intention was that   if a source is not listed, it should not be able to reach any service or port What is a good way to catch the Mysterious Stranger? When ever I hear the music to indicate the Mysterious Stranger has arrived, I can never find him. It is almost like he is not in the vault.  What is a good way to catch the Mysterious Stranger? Where does he usually show up? `--no-install-recommends` only specified packages I want to install xfce4-goodies but I don't want Midori Browser. With --no-install-recommends I don't know how to specify only Midori. I want the rest of packages. How to do that? Thanks! Evaluating $\zeta(0)$ using the functional equation of Riemann-Zeta function. $$\zeta(it)=2it\pi it−1\sin(i\pi t/2)\Gamma(1−it)\zeta(1−it).$$ Everything on the RHS is never zero,  Does that means LHS has no zeros, since $\sin(s)$ has a simple zero at $s=0$ while $\zeta(1−s)$ has a simple pole at $s=0$  (the Laurent expansion), so the product $\sin(i\pi t/2)\zeta(1−it)$ is finite and nonzero at $t=0$.  My question is that from functional equation one can't get direct answer $\zeta(0)=−1/2$ unless using alternate infinite series ! Argue by contradiction to show that there is no surjection... from $A$ to $\{0,1\}^A$. When $A$ is any (possibly infinite) set  How does one go about this? Most common C# bitwise operations on enums For the life of me, I can't remember how to set, delete, toggle or test a bit in a bitfield. Either I'm unsure or I mix them up because I rarely need these. So a "bit-cheat-sheet" would be nice to have.  For example:   flags = flags | FlagsEnum.Bit4;  // Set bit 4.   or  if ((flags &amp; FlagsEnum.Bit4)) == FlagsEnum.Bit4) // Is there a less verbose way?   Can you give examples of all the other common operations, preferably in C# syntax using a [Flags] enum? unicode-math broken How can aperture be f/11 on a lens with an aperture range designation of 3.5-5.6? Are $10\times 10$ matrices spanned by powers of a single matrix? I don't know how to answer this question:     Is there a $10 \times 10$ matrix $A$ such that $$M_{10}(\mathbb{F})=\text{span}\{I,A,A^2,\ldots, A^{100}\}\textrm{,}$$ where $M_{10}(\mathbb{F})$ is the vector space of $10 \times 10$ matrices over $\mathbb{F}$?   I think there is a connection to Jordan normal form. Bootable USB of Ubuntu Minimal CD I want to burn Ubuntu Minimal CD ISO to an old, 1 GB USB thumbdrive. Regular ISO doesn't fit. I already tried Startup Disk Creator and Unetbootin but both failed. I tried installing GRUB and pointing it to boot like this:  insmod part_msdos linux /linux initrd /initrd.gz   but it doesn't work. I also tried dd but I ended up with not bootable drive.  Rufus worked on Windows with the same thumbdrive but I no longer use Windows.  What else can I do? I am trying to make a snowball that triggers a command when it hits a player in 1.15, but I don't know how to do that. When I do execute at @e[type=snowball] run gamemode spectator @a[distance=..2] it only runs the command if it goes right next to them. My Realtek NIC in my Windows Home Server (essentially w2k3) box refuses to run at 1000Mb/s even if I change the driver settings from Auto Negotion to 1000Mb/s full duplex. I've installed the latest driver and tried changing the speed setting but I'm having no luck. Not sure what to try next. Any ideas?  I have a Netgear GS605 v2 Switch supports 10/100/1000 D Link DIR 655 router.  All my machines bar one/2 have 1000Mb/s NICs (Old laptop/Xbox being the exceptions)  The reason I noticed the problem was because I was copying files between two machines and maxing one NIC out and only seeing 10% on the other machine. I do have a fairly lengthy cable between the switch and the router (maybe 20m) could that be the issue? Syntax error while defining an array as a property of a class Why does my shell script choke on whitespace or other special characters? Or, an introductory guide to robust filename handling and other string passing in shell scripts.  I wrote a shell script which works well most of the time. But it chokes on some inputs (e.g. on some file names).  I encountered a problem such as the following:   I have a file name containing a space hello world, and it was treated as two separate files hello and world. I have an input line with two consecutive spaces and they shrank to one in the input. Leading and trailing whitespace disappears from input lines. Sometimes, when the input contains one of the characters \[*?, they are replaced by some text which is is actually the name of files. There is an apostrophe ' (or a double quote ") in the input and things got weird after that point. There is a backslash in the input (or: I am using Cygwin and some of my file names have Windows-style \ separators).   What is going on and how do I fix it? How can I migrate a Windows 10 from BIOS/MBR boot to UEFI/GPT without reinstalling? Show $\operatorname{Aut}(C_2 \times C_2)$ is isomorphic to $D_6$ (the group with $x^3=1$, $y^2=1$ and $xy=yx^2$).  I'm not really sure how to express the elements of $\operatorname{Aut}(C_2 \times C_2)$. Would it be sufficient to show the elements of $\operatorname{Aut}(C_2 \times C_2)$, find their order and show they bijectively map to every element of $D_6$ and satisfy $xy=yx^2$?