If $2^x=0$, find $x$.
If $2^x=0$, find $x$. Solution: I know range of $2^x$ function is $(0,\infty)$. So $2^x=0$ is not possible for any real value of $x$ Hence, equation is wrong. We can't find value of $x$. Am I …
In languages that don't allow underscores in integer constants, is it a good practice to create a constant for 1 billion?
In languages that don't allow underscores in integer constants, is it a good idea to create a constant for 1 billion? e.g. in C++: size_t ONE_BILLION = 1000000000; Certainly, we shouldn't create …
Why arrow keys are not recommended in Vim
"Never use arrow keys in Vim!" I heard this from a random speaker, but didn't have the chance to ask him why. Also, if you don't use the arrow keys, how can you move the cursor in the Insert ...
explaining the derivative of $x^x$
You set the following exercise to your calculus class: Q1. Differentiate $y(x) = x^x$. A student submits the following solution: Let $g(a)=a^x$ and $f(x)=x$. Then $y(x) = g(f(x))$, so by …
Why does the email subject appear before the body when composing an email?
Note: I am not talking about reading experience, I am focusing on the experience of composing email. I am very aware of this issue since it happens to me all the time, and I am pretty sure that it …
Infinite series and its upper and lower limit.
I am learning analysis on my own and I am puzzled with the following question. Consider the series $$\frac{1}{2}+\frac{1}{3}+\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{2^3}+\frac{1}{3^3}+\cdots$$ ...
Players who want a dayjob for a megacorp. Should I allow it?
A player wants to work for EVO knowing the corp has a great reputation as an employer (according to Corporate Guide) and they have a great tolerance of technomancers. As part of the day job ...
Get the head, the tail, and the last element of a comma-separated list
I have a comma-separated list, stored in a macro. It is non-empty, and it has commas between the elements but not at the start or end. How can I get: the first element (a.k.a. the "head")? the last …
How to use wildcards for string conditionals using bash?
I want to see if a string is inside a portion of another string. e.g.: 'ab' in 'abc' -> true 'ab' in 'bcd' -> false How can I do this in a conditional of a bash script?
Why do some photographers cover up the brand-name on their camera?
I have a professional photographer friend. He works for news agencies. He covers up the brand name on his cameras. This was the only photo I could find from him with his camera but it shows the ...
Did the FBI agents responsible for killing Tamerlan Tsarnaev die together during a FBI training exercise?
A viral image is being passed around Facebook claiming that two FBI agents who fell from a helicopter to their deaths during a training accident were the same two who killed Tamerlan Tsarnaev (of the …
How do I factor this?
How do I factor $p^2+8pq+16q^2-9r^2$? I know how to group the first two terms, but I dont know what to do with the other half. Can someone help me with this problem?
What is the best way to prevent abuse of the gate spell?
The gate spell may be used for calling a extraplanar creature up to 39 HD for your service, e.g. Solar. That creature may be commanded to use wish spell for raising your attributes or for creating a …
Having used Mathematica as a “gateway” language, where to from here?
I have been using Mathematica for about a year. It is the first language that I have attempted to learn. I'm still very much a newbie, but there are moments I feel more like I am waving than drowning. …
Name of text describing an action in a play
I'm trying to find the name of an element of playwriting which describes actions performed by actors in a play. For example, Let me see. Picks up skull Alas, poor Yorick! The element …
\d is less efficient than [0-9]
I made a comment yesterday on an answer where someone had used [0123456789] in a regular expression rather than [0-9] or \d. I said it was probably more efficient to use a range or digit specifier ...
Should unreadability or sloppiness of students' work be reflected in their evaluation?
When evaluating and grading students' work in technical fields (like computer science or mathematics), I often face ones that are really messy, sometimes even unreadable (I mean structure, not - ...
Where does the function $f(x) = \frac{2x}{x - 7}$ have an increasing slope?
Where does the function $f(x) = \frac{2x}{x - 7}$ have an increasing slope? $a. x \le 0, x > 7$ $b. x<7$ $c. x > 7$ $d. x \in \Bbb R, x \neq 7$ This question is from a test of mine in a …
Why are reboot, shutdown and poweroff symlinks to systemctl?
In Arch Linux, if I do ls -l in /sbin, I can see that reboot, shutdown and poweroff are all symlinks to /usr/bin/systemctl. But issuing reboot, shutdown and systemctl commands obviously does not all …
Networking with VMware, physical adapters and iSCSI
New VMware user here, setting up my first environment. I have an ESXi host that has four physical NiCs (NiC0, NiC1, NiC2, NiC3). I have installed ESXi, the VCVA appliance, and several VMs ...
Meaning of inner product $\langle \vec{r} | \psi(t)\rangle $
I have come across the equation which comes out of the nothing in Zettili's book Quantum mechanics concepts and applications p. 167: $$\psi(\vec{r},t) ~=~ \langle \vec{r} \,|\, \psi(t) \rangle.$$ …
Is it OK to ask for detailed feedback even after I got an offer?
Is it OK to ask the hiring manager for feedback on myself even if I have already got the offer? I just really want to know how I perform, especially comparing to other candidates.Also I believe the …
Where do I connect a road to?
I'm trying to plan out my new fortress before I start construction, but I'm not sure where the road must go. I'd like to ensure that I don't need to construct a road right across the entire map. Is …
How to evaluate $\lim_{x\to 0} (1+2x)^{1/x}$
Good night guys! I'm having some trouble with this: $$\lim_{x\to 0} (1+2x)^{1/x}$$ I know that $\lim_{x\to\infty} (1 + 1/x)^x = e$ but I don't know if i should take $h=1/(2x)$ or $h=1/x$ Can ...
IMG tag vulnerability
Is it safe to display images from arbitrary domains? I.e. let's say I have an image on my page: <img src="http://badguy.com/image.gif" /> What if image.gif will return some js attack vector, …
Sequences with the following properties…
Suppose that $\lim_{n\to\infty}\frac{a_n}{b_n}$=1. And $\sum^{\infty}_{n=1}a_n$ converges, $\sum^{\infty}_{n=1}b_n$ diverges. Are such sequences $(a_n)$, $(b_n)$ exist?
Do I reset XP to zero on a new level?
In the D&D group I play with one of the players insists that when you reach a new level you have to zero your experience. However when I checked the PHB1 there is no reference to this. PHB1 uses …
Alternative to trains in Japan
So we all know about these pretty amazing trains they have in the "Land of the Rising Sun". They are always on time, clean, comfortable. But they are somewhat expensive for the average backpacker. …
Accumulation points of accumulation points of accumulation points
Let $A'$ denote the set of accumulation points of $A$. Find a subset $A$ of $\Bbb R^2$ such that $A, A', A'', A'''$ are all distinct. I can find a set $A$ such that $A$ and $A'$ are distinct, but not …
Should portfast be used on a port potentially connecting to an unmanaged switch?
I understand the basics of how spanning tree works and why you would want to use portfast on user access ports. When dealing with a topology with a large number of dumb switches under desks and ...
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