I have pretty much every single hard mode weapon, but I have killed a bunch of diabolists, and haven't got one! Is there a way to increase the drop chance?
Some items in Terraria drop only very rarely from certain enemies. It's a pain having to farm so many enemies to try to get these rare items. Is there any way to make them drop more often?
Are universal power supplies for laptops worth it? My laptop's cable broke and sadly it seems like I need to buy a new power supply.  What I wonder is, I've found that universal power supplies are much cheaper than the official HP ones. Are they really worth it?  Another question: the original supply has these specs: 65W, 18.5V, 3.5A. However the universal supplies are more powerful (90W, 100W) and come in integer voltages (17V, 18V, 19V, etc). Are they compatible? Should I set them to 18V or 19V? How to add a Login / Logout link in Main navigation menu? How can I add a Login link to the "Main navigation" menu?  When a user clicks on the link, it should take them to the /user/login page. Once they login, the link should change to say "Logout" instead of "Login".  Is there any way to add such a link? I'd like to implement a big int class in C++ as a programming exercise&mdash;a class that can handle numbers bigger than a long int.  I know that there are several open source implementations out there already, but I'd like to write my own.  I'm trying to get a feel for what the right approach is.  I understand that the general strategy is get the number as a string, and then break it up into smaller numbers (single digits for example), and place them in an array.  At this point it should be relatively simple to implement the various comparison operators.  My main concern is how I would implement things like addition and multiplication.  I'm looking for a general approach and advice as opposed to actual working code. Simplifying and evaluating $\cot 70^\circ+4\cos 70^\circ$ I'm reading through  for the , which contains this figure on page 16:    This is of course an instrumentation amplifier that apparently uses an inverting amplifier's output instead of a ground in the lower-right corner of the above figure, but what really perplexes me is the 100 k&Omega; resistors attached directly to the noninverting inputs of three of the four amps. I don't recall seeing an instrumentation amplifier circuit in books or application notes that have them, and all of the instrumentation amplifiers I've built using the three op-amp scheme works fine without them.  The datasheets specifies an input resistance of 1012 &Omega;, which is 10,000,000 times greater than 100 k&Omega;, so it doesn't seem to add anything to the already high-impedance JFET inputs. I thought perhaps it has something to do with input bias currents, but that's just me making a wild stab in the dark.  Curiously, figure 26 in the same datasheet (page 18) shows a two-op-amp version of an instrumentation amplifier without the 100 k&Omega; resistors at the noninverting op-amp inputs!  What's the purpose of the 100 k&Omega; resistors at the noninverting inputs in the above circuit? Am I missing something completely obvious? Non-empty intersection. Let $A_1,A_2,...,A_{2019}$ be sets s.t. $|A_i|$=45 for each $i=\overline{1,2019}$ and $|A_i\cap A_j|=1$ for every $i\neq j$. Is it true that $$\Big|\bigcap _{i=1}^{2019} A_i\Big|=1?$$ What I thought of doing is proving by induction by i, the base is obvious. However I'm stuck on the next step. Suppose we view fluids classically, i.e., as a collection of molecules (with some finite size) interacting via e&amp;m and gravitational forces. Presumably we model fluids as continuous objects that satisfy some differential equation. What mathematical result says that modeling fluids as continuous objects can accurately predict the discrete behavior of the particles? I don't know anything about fluid mechanics, so my initial assumption may in itself be wrong. How to understand the Ubuntu file system layout? Post Problem Analysis - Rod in a cylindrical time varying magnetic field? A metal rod of length $l$ is placed (as shown in figure) in a cylindrical time varying magnetic field. Find the potential difference across it.   My answer:  As electric fields as forming circles around the centre with magnitude $$\frac12r\frac{dB}{dt}$$ whose magnitude is same along any chord at a fix distance from centre: $$\Delta V=E.l=\frac12r\frac32at^{\frac12}.l$$ $$\Delta V=\frac34arlt^{\frac12}$$  My question: Is $\Delta V =V_M-V_N$ or $\Delta V=V_N-V_M$ $\bf OR$ equivalently which side is at high potential?  Possible    $(i)$ As Field lines are circular from $M$ to $N$, $M$ must be high potential. $(ii)$ As this field line apply a force on electrons- in the rod- towards left, then $M$ must have excess $e^-$ and $N$ must have deficiency; so $N$ would be high potential as $M$ is $(+)$ and $N$ is $(-)$. Idiom or expression that would imply "someone is a habitual liar" I'm looking for an idiom or expression for describing people who tell lies out of habit (so you cannot trust them at all).   I know that these people are called , but I'm not looking for psychological terms.  Is there any idiom or expression for describing such people?   For example:     "Did X tell that to you?! Come on, don't believe him/her. Don't you know he/she ___ (=is a habitual liar)?" Every nonzero element in a finite ring is either a unit or a zero divisor Let $R$ be a finite ring with unity. Prove that every nonzero element of $R$ is either a unit or a zero-divisor. TV identification: Short-lived TV show about a time traveller with a super-computer disguised as a credit-card It might have only been a pilot or a made for TV movie, but I remember a male time traveller who was for some reason in 90s US from a semi-distant future. He had in his possession a super-computer disguised as a regular credit card, which could hack things and I think spoke to him in a female voice.   Note: Not Quantum Leap - the time traveller and "credit card computer" might be keywords that people would hit upon, but 'Ziggy' the computer in QL was non-speaking, operated by a hologram and did not resemble a credit card - this one had its own voice and was disguised as a CC. Typesetting Chemical Formulas Is there a consensus in the mathematical community, or some accepted authority, to determine whether zero should be classified as a natural number?  It seems as though formerly $0$ was considered in the set of natural numbers, but now it seems more common to see definitions saying that the natural numbers are precisely the positive integers. I clicked on  to a comment in my email and it prompted a list of apps to open link. All browsers (Chrome, Firefox and etc) are in the list, but not SE app.  Most apps that can open site specific links get prompted for that app to open  the link, but not Stack Exchange links for some reason.    App Version: 1.0.95 Device Manufacturer: Asus Device Model: ASUS_Z010D   OS Version: 6.0.1 (WW_Phone-13.8.26.76-20161230) Does the logistic map have an attractor for a particular value of the parameter? Background:  Currently I am studying a course on non-linear dynamics. We have been studying about attractors only intuitively, so I do not have a definition for an attractor. Let me give you a couple of examples.  Consider a problem where a ball is slipping in a parabolic valley. It is clear intuitively and quantitatively that the lowermost point of the parabola is the attractor for it.   Say we are talking about a . We may not guess intuitively that there is an attractor, a priori, but using simulations for different values of initial conditions, we may qualitatively (and maybe quantitatively too) compare the trajectories for different initial conditions and convince ourselves that we have an attractor.  Problem:  Consider the  given as   $$x_n = ax_{n-1}{(1-x_{n-1})}.$$  Let us fix a value of the parameter where we "know" that the logistic map exhibits chaos. Say $a=3.9$.  Let us take the definition for the term attractor from :  An attractor is a subset $A$ of the phase space characterized by the following three conditions:   $A$ is forward invariant under $f$: if $a$ is an element of $A$ then so is $f(t,a)$, for all $t &gt; 0$. There exists a neighborhood of $A$, called the basin of attraction for $A$ and denoted $B(A)$, which consists of all points $b$ that "enter $A$ in the limit $t → ∞$". More formally, $B(A)$ is the set of all points $b$ in the phase space with the following property: For any open neighborhood $N$ of $A$, there is a positive constant $T$ such that $f(t,b) ∈ N$ for all real $t &gt; T$. There is no proper subset of $A$ having the first two properties.   How might we demonstrate/convince ourselves of/disprove the statement that the logistic map does have an attractor for a particular choice of the parameter at which the map exhibits chaos? I'm practicing proofs and given the following statement:  Let $\Sigma$ be an alphabet, $\epsilon$ the empty word and $\sigma:\Sigma^{*}\rightarrow\Sigma^{*}$ an operation which for $a\in\Sigma$ and $w\in\Sigma^{*}$ is defined as $$\sigma(\epsilon)=\epsilon,\\\sigma(wa)=a\sigma(w).$$  I would like to prove through induction that $\sigma$ is equal to the word reversal operation $rev$ meaning that $\sigma(w)=rev(w)=w_{n}...w_{1}$ for every $w=w_{1}...w_{n}\in\Sigma^{*}$.  My suggestion is as follows:  For $w=\epsilon$ we have $$\sigma(w)=\sigma(\epsilon)=\epsilon=rev(\epsilon)=rev(w).$$  Let $w=xa$ with $x\in\Sigma^{*}$ and $a\in\Sigma$, then $$\sigma(x)=x_{n}...x_{1}=rev(x).$$  Thus we also have $$\sigma(w)=\sigma(xa)=\sigma(x_{1}...x_{n}a)=a\sigma(x_{1}...x_{n})=ax_{n}\sigma(x_{1}...x_{n-1})=...=ax_n...x_{1}=rev(x_{1}...x_{n}a)=rev(xa)=rev(w).$$  Does that constitute a correct and sufficient proof? If not, I would very much appreciate your feedback. Why is defragmentation unnecessary? Sentence vs proposition What is Skynet's ultimate goal after defeating the resistance?