I'm studying some notes on latches and flip flops. After the introduction of the D flip flop, the notes go on to explain its function - how it works. However, the first circuit diagram contains this weird circuit symbol :     Does anyone recognize it?   In case it helps, here's the full circuit diagram :     Could it be just a symbol replacing the whole D flip flop? In that case the inverters seem to be there so that we can get the 2 complementary Q outputs. I don't get the whole feedback thing though.
Could someone please tell me what the symbol ringed in red represents?     I know it has ON Switch pointing to it, but the symbol has other lables in different parts of the document.
Equivalent of *Nix 'which' command in PowerShell? How do I ask PowerShell where something is?    For instance, "which notepad" and it returns the directory where the notepad.exe is run from according to the current paths. Simulating draws from a Uniform Distribution using draws from a Normal Distribution I recently purchased a  in which one of the probability questions was as follows:     Given draws from a normal distribution with known parameters, how can you simulate draws from a uniform distribution?   My original thought process was that, for a discrete random variable, we could break the normal distribution into K unique subsections where each subsection has an equal area under the normal curve. Then we could determine which of K values the variable takes by recognizing which area of the normal curve the variable ends up falling into.   But this would only work for discrete random variables. I did some research into how we might do the same for continuous random variables, but unfortunately I could only find techniques like inverse transform sampling that would use as input a uniform random variable, and could output random variables from some other distribution. I was thinking that perhaps we could do this process in reverse to get uniform random variables?  I also thought about possibly using the Normal random variables as inputs into a linear congruential generator, but I'm not sure if this would work.  Any thoughts on how I might approach this question? Use 'import module' or 'from module import'? Hide textfield blinking cursor I have a list of cards for a deck I want to build or buy. What should I do to check whether that deck is legal in a particular format (Standard, for example)? Prove that a product of two complex numbers has zero imaginary part This is my homework, which reads as follows: Let $z_1, z_2$ be complex numbers.  Prove that when $z_1z_2 \neq -1$ and $|z_1| = |z_2| = 1$, then the imaginary part of $$ \frac{z_1 + z_2}{1 + z_1z_2} $$ is zero.  I've tried to approach this in several ways, but whichever one I try, at some point the expression gets too large and doesn't simplify (at least I cannot find a way to simplify it).  The way I tried to approach this problem is to:   Set $z_1 = a+bi$, $z_2 = c+di$, then $z_1+z_2=(a+c)+(b+d)i$, and in polar form, $\sqrt{(a + c)^2 + (b + d)^2}\times (\cos\theta + i\sin\theta)$, $\tan \theta = \frac{b+d}{a+c}$. Find $\tan \phi$, where $\phi$ is the angle of $\frac{1}{1 + z_1z_2}$. Substitute into $\tan(\theta + \phi) = \frac{\tan(\theta)+\tan(\phi)}{1-\tan(\theta)\tan(\phi)} = 0$.   The problem is $\tan(\phi)$ is a huge expression, and I cannot get it to simplify, so I cannot also show that the last formula is actually true.  Since this is a homework, and we are expected to do this with pan and paper (not even a calculator...), I don't believe we are to do this many calculations by hand.  Hence, there must be some "trick" to get this to simplify, or a completely different approach.  Would you care to give me a hint? How to have a one-to-many relationship with a privileged child? In Bash, two integers can be compared using conditional expression     arg1 OP arg2      OP is one of -eq, -ne, -lt, -le, -gt, or -ge. These   arithmetic binary operators return true if arg1 is equal to, not equal   to, less than, less than or equal to, greater than, or greater than or   equal to arg2, respectively. Arg1 and arg2 may be positive or negative   integers.   or arithmetic expression:     &lt;= &gt;= &lt; &gt; comparison      == != equality and inequality   Why do we have two different ways for comparing two integers? When to use which?  For example, [[ 3 -lt 2 ]] uses conditional expression, and (( 3 &lt; 2 )) uses arithmetic expression. Both returns 0 when the comparison is true  When comparing two integers, can these two methods always be used interchangeably? If yes, why does Bash have two methods rather than one? Three-columns text with figures of 2\columnwidth How to delete file(s) in secure manner? Is there a way to make sure that a deleted file can not be recovered?   As you know, deleting a file by pressing shift-del or using trash doesn't mean that file is gone forever. It resides somewhere in the computer.  In day to day life, law enforcement or thieves use recovery programs to reveal our private data or something else.   They can recover all data that resides on hard disk, in RAM, and even USB.  To protect us from these people, what should one do? Which program should one use?  Note: I don't want an answer like first use a recovery program then erase that file with shred. With just one program, I want to erase all unused/deleted files on my computer. How do I disable overlay scrollbars? It looks like Ubuntu 11.04 will come with  by default. I do like them, but I don't like the current mix of scrollbar types as many applications don't yet use those overlay scrollbars.  Is there a way to disable overlay scrollbars (without removing the overlay-scrollbar package)? Sunlight Sensitivity looks pretty bad — Disadvantage to attack rolls and Perception checks whenever you, your target, or what you're trying to perceive are in direct sunlight. I hope I'm missing something, since no other PC race has a comparable hindrance.  Are there any ways you have used to mitigate this flaw to make players of this race not at a severe disadvantage (or, if it doesn't need mitigation, explain why it's already balanced without any action required)? Prove or disprove an inequality involving complex numbers Consider following inequality:     $|z_1 + z_2|\ge|z_1| - |z_2|  \  \ \ \ \ \  z_1,z_2 \in \mathbb{C}$   Is that true always? I tried many examples and it was correct but I don't know how to prove that if it's right. How do I start a process from C#? How do I start a process, such as launching a URL when the user clicks a button? Thermodynamics of supercooled water Now that it's been freezing outside for the last few days, I experimented a bit with supercooling. I've left a bottle of clean water outside for a few hours, and behold, when I shook the bottle, the liquid began to freeze rapidly, as expected.   However, not all of the water froze, only about half of it. This got me thinking.  I reasoned that happens because freezing releases heat, and that heat raises the temperature of the ice and remaning water to 0$^\circ$C, at which point the freezing stops.  To try to quantify this, set   $H_f = 334000 \frac{J}{kg}$, the "freezing heat" (enthalpy of fusion) of ice, $c_i = 2110 \frac{J}{kg\cdot K}$, specific heat of ice, $c_w = 4181 \frac{J}{kg\cdot K}$, specific heat of water, $M$, initial mass of supercooled water, $T_0$, initial temperature of supercooled water, $m$, mass of ice at a given moment, $T$, temperature at a given moment.   We suppose that the energy released by the freezing of a $\textrm dm$ mass of ice is used up by raising the temperature of both the already frozen ice ($m$) and the remaining water ($M-m$):  $$ \textrm dm \cdot H_f = c_i m \cdot\textrm dT + (M-m)c_w \cdot\textrm dT$$  By rearranging we get a linear differential equation for $m(T)$:  $$\frac{\textrm dm}{\textrm dT}+\frac{c_w-c_i}{H_f}m = \frac{c_w}{H_f}M$$  The solution of this equation, using the initial condition that at $T=T_0$, $m=0$:  $$ m = M \frac{c_w}{c_w-c_i}\left[ 1-e^{-\frac{c_w-c_i}{H_f}(T-T_0)} \right]$$  This looks neat, however, plugging in the actual values of the constants, $T = 0^\circ$C and $T_0 = -6^\circ$C, I get that little more than 7% of the water should freeze - as opposed to more than half, as I've observed. What's worse, the formula can be used to calculate the starting temperature required to freeze all the supercooled water: $$T_{all} = \frac{H_f \log\frac{c_w}{c_i}}{c_i-c_w}=-110.26^\circ \textrm C$$ which seems absurd.  Where is the error in the calculation above?  I've made a number of assumptions which may or may not hold:   the constants are really constant. I think this is a good approximation for $c_w$, a not that good but still acceptable approximation for $c_i$, and I suppose it holds to $H_f$ to some extent as well. there is no heat transfer with the environment, i.e. the bottle is a closed system. The process seemed fast enough (a few seconds at most) for this to be a good approximation. the system is in a thermal equilibrium at all times and the heat released by the freezing of the ice is distributed evenly in the emerging ice-water mixture. Now this is where I have doubts. Precisely because of the process happening so fast, this might not be true at all. However, acknowledging the presence of temperature variations makes the problem order of magnitudes harder: one has to solve a system of partial differential equations that take heat transfer, the shape of the bottle and \$deity knows what else into account. Algebra - Solving for three unknowns. Find all possible solutions of $$2^x + 3^y = z^2.$$    My approach.   First I substituted $x = 0$, and got the solution, then for $y = 0$. And for $x &gt;  0$ and $y &gt; 0$ , I just know the Pythagorean triple and got the solution as $(4,2,5)$ and $(4,2,-5)$. Please help me to solve it properly. A secretary with ____ good knowledge of English: "a" or no article? I'm trying to pass a test on "Articles exercise" as they call it . Reviewing my answers I got stuck about the two I posted on the picture below.  As I understand both words are uncountable (according to the ), so it looks like (or said for example ) I can't say a/an with an uncountable noun.  But this test says the opposite. Is there some trick? Or am I just dumb? Please help me to understand why I need to use "a" article in these cases?        We need a secretary with ____ good knowledge of English.          a  (marked as the correct answer)   the     a / the     no article is needed (the answer I think is correct)        We're having ____ terrible weather.         a (marked as the correct answer)     the     a / the     no article is needed (the answer I think is correct) How can one prove the Bohr-Sommerfeld quantization condition $$ \oint p~dq ~=~2\pi n \hbar $$ from the WKB ansatz solution $$\Psi(x)~=~e^{iS(x)/ \hbar}$$ for the Schroedinger equation? With $S$ the action of the particle defined by Hamilton-Jacobi equation $$ \frac{\partial S}{\partial t}+ \frac{(\nabla S)^{2} }{2m}+V(x)~=~0 .$$ Should I test private methods or only public ones? If a function can only be defined implicitly does it have to be multivalued?