Scorching Ray as an attack of opportunity from War Caster
Can high level Eldritch blast be used with War Caster?
What is a "callback" in C and how are they implemented? From the reading that I have done, Core Audio relies heavily on callbacks (and C++, but that's another story).    I understand the concept (sort of) of setting up a function that is called by another function repeatedly to accomplish a task.  I just don't understand how they get set up and how they actually work.  Any examples would be appreciated. Modified Hamilton's Principle overconstraining a system by imposing too many boundary conditions In Hamiltonian Mechanics, a version of Hamilton's principle is shown to evolve a system according to the same equations of motion as the Lagrangian, and therefore Newtonian formalism. In particular, letting $\delta$ indicate a variation of the path through phase space, $$ \delta \int_{t_1}^{t_2} \big(p_i \dot{q}_i - H(p_i,q_i,t)\big)dt = 0 $$ is shown to generate the same motion equations as those found by the Legendre transform of the Lagrangian equations of motion. Essentially, when we calculate the Euler-Lagrange equations for the above integrand, we find $$ \dot{p}_i + \frac{\partial H}{\partial q_i} = 0\text{, } \dot{q}_i - \frac{\partial H}{\partial p_i} = 0. $$ Now, since these are both first-order equations of motion, we require $2n$ boundary conditions to obtain a solution, where $n$ is the number of particles. This is perfectly consistent with the Lagrangian formalism which had $2n$ boundary conditions due to its $n$ distinct second-order motion equations.   An important thing to note is that since $p_i\dot{q}_i - H(p_i,q_i,t)$ contains no $\dot{p}_i$ dependence, the variation in $p_i(t)$ need not be zero at the endpoints of the path. This is not the case with $q_i(t)$ because the $\dot{q}_i$ dependance results in the appearance of boundary terms that must be set to zero in order to obtain the motion equations.  Now, as far as the boundary conditions are concerned, this makes sense. For the path to be uniquely specified given Newtonian mechanics, we require $2n$ boundary conditions. These can either be the usual Newtonian choice of initial positions and velocities/momenta, or they can be the initial and final positions. Both are perfectly acceptable mathematically speaking. If we were required, in the modified Hamilton's principle variation, to enforce that the variations in the momenta also be zero at the initial and final times, this would mean $2n$ additional boundary conditions, which would generally over constrain a Newtonian system.   However, my confusion is this: when textbooks (Goldstein in particular) consider generating functions, they require that the integrand be invariant to the addition of a total time derivative of a function $F(q_i,p_i,t)$ of the phase space coordinates. However, adding such a function will in general add some $\dot{p}_i$ dependence to the integrand, which will then add boundary terms to the equations of motion unless we require that the $p_i(t)$ variations be zero at the boundaries. This is fine as far as it goes. We can always define the variation however we like. The point is just that it spits out the right motion equations at the end of the day. But my confusion lies in how this doesn't generally over constrain the system. If we specify all the positions and momenta at both the initial and the final times, might not the required path to connect those points in phase space be non-Newtonian? Does this only matter if you're actually trying to use the stationary action principle to find the paths, rather than just using it to find the motion equations? Why are all nonzero eigenvalues of the skew-symmetric real matrices pure imaginary? Assume that $A$ is an $n\times n$  real matrix, i.e. $$A^T=-A.$$  Since $\det(A-\lambda I)=\det(A^T-\lambda I)$, $A$ and $A^T$ have the same eigenvalues. On the other hand, $A^T$ and $-A$ also have the same eigenvalues. Thus if $\lambda$ is an eigenvalue of $A$, so is $-\lambda$. If $n$ is odd, $\lambda = 0 $ is an eigenvalue.  A curious search in Google returns  the nonzero eigenvalues of $A$ are all pure imaginary and thus are of the form $iλ_1, −iλ_1, iλ_2, −iλ_2,$ … where each of the $λ_k$ are real.   Here is my question:     How can I prove the fact that "the nonzero eigenvalues of $A$ are all pure imaginary"? Analyzing $\biggl\lfloor{\frac{x}{5}}\bigg\rfloor=\bigg\lfloor{\frac{x}{7}}\bigg\rfloor$ How many non negative integral values of $x$ satisfy the equation :$$\biggl\lfloor{\dfrac{x}{5}}\bigg\rfloor=\bigg\lfloor{\dfrac{x}{7}}\bigg\rfloor$$.   My try:  Writing few numbers and putting in the required equation.  $\underbrace{0,1,2,3,4}_{\implies 0=0},\underbrace{5,6}_{\displaystyle\times},\underbrace{7,8,9}_{\implies 1=1},\underbrace{10,11,12,13}_{\displaystyle\times} ,\underbrace{14}_{\implies 2=2},\underbrace{15,16,17,18,19,20}_{\text{LHS gives 3 but RHS gives 2}},\underbrace{21,22,23,24}_{\text{LHS gives 4 but RHS gives 3}}$.  The point which I wish to make here is that after $14$ we'll get $5's$ multiple before than $7's$, hence $\forall x \geq 15 \implies \biggl\lfloor{\dfrac{x}{5}}\bigg\rfloor&gt;\bigg\lfloor{\dfrac{x}{7}}\bigg\rfloor$  Hence the only solution are: $\{0,1,2,3,4,7,8,9,14\}$. Does these make sense?  I need to know other solutions that don't incorporate such analyzing, means using some properties and framing it to solve above. Why doesn't Mac OS X source ~/.bashrc? Can I mix sources from different ubuntu versions? As we know that we are using  for installing packages and repositories configuration file located at /etc/apt/sources.list.  I am using Ubuntu 12.10 (Quantal Quetzal) which reaches . That means no updates or support. So, the question is, can I use sources.list file from another version, say Ubuntu 12.04 LTS, and will it negatively affect the system. Why are all the textures in my file pink? I made a character, and its one of my first times texturing, and I saved my character into a new folder, and when I came back to the model ALL the textures were pink, I used to know what to do, but I stopped texturing, how do I bring my textures back? How do I figure out what package something is in without resorting to Google? I often find myself wanting to install something, but I'm unsure of what package it's in. This is a very common occurrence for me:  $ make html sphinx-build -b djangohtml -d _build/doctrees   . _build/html make: sphinx-build: Command not found make: *** [html] Error 127  $ sudo apt-get install sphinx E: Unable to locate package sphinx  $ sudo apt-get install sphinx-build E: Unable to locate package sphinx-build   googles  $ sudo apt-get install python-sphinx   Is there a better way? How to securely delete files stored on a SSD? Boot problem after hanging and manual power off ( Stopping User Manager for UID 121... ) My Ubuntu stalled while running Android's VirtualBox version, so I powered off the system. But after reset it stopped during this line:     Stopping User Manager for UID 121... _ So i googled it and have read  question and tried these steps:  Boot into Recovery Mode, drop to a root shell, and follow the steps below:   Run mount -o rw,remount / to mount the drive in Read-Write mode.Run sudo apt-get purge nvidia-* to purge the NVIDIA driver.You may also need to purge xserver-xorg and reinstall it, which will  require you to enable networking in Recovery.Reboot. You may have to add the nouveau.modeset=0 flag in GRUB to boot properly (Check my Q&amp;A for specifics).   You should be past the screen flicker and be at your desktop.  But in doing this step:  Now reinstall the NVIDIA drivers the proper way:sudo apt-get install  nvidia-367 (or 340, 352, 364, 370, whichever works).Reboot again.  I found i have not internet, and my WiFi is not in ifconfig list!!! By running :     Iw wlp2s0 scan   I get :  N180211 not found I also search for it and not understand why WiFi gone off. Now i thinking to use live USB of ubuntu to download NVIDIA and xserver-xorg and the install the by dpkg command during tty2. Update : in Ubuntu live i have this settings :  ubuntu@ubuntu:~$ sudo lshw -c video   *-display                         description: VGA compatible controller        product: HD Graphics 620        vendor: Intel Corporation        physical id: 2        bus info: pci@0000:00:02.0        version: 02        width: 64 bits        clock: 33MHz        capabilities: pciexpress msi pm vga_controller bus_master cap_list rom        configuration: driver=i915 latency=0        resources: irq:129 memory:a2000000-a2ffffff memory:b0000000-bfffffff ioport:6000(size=64) memory:c0000-dffff   *-display        description: 3D controller        product: GM108M [GeForce 920MX]        vendor: NVIDIA Corporation        physical id: 0        bus info: pci@0000:03:00.0        version: a2        width: 64 bits        clock: 33MHz        capabilities: pm msi pciexpress bus_master cap_list        configuration: driver=nouveau latency=0        resources: irq:128 memory:a3000000-a3ffffff memory:90000000-9fffffff memory:a0000000-a1ffffff ioport:3000(size=128)  and ubuntu@ubuntu:~$ sudo lshw -c display   *-display                         description: VGA compatible controller        product: HD Graphics 620        vendor: Intel Corporation        physical id: 2        bus info: pci@0000:00:02.0        version: 02        width: 64 bits        clock: 33MHz        capabilities: pciexpress msi pm vga_controller bus_master cap_list rom        configuration: driver=i915 latency=0        resources: irq:129 memory:a2000000-a2ffffff memory:b0000000-bfffffff ioport:6000(size=64) memory:c0000-dffff   *-display        description: 3D controller        product: GM108M [GeForce 920MX]        vendor: NVIDIA Corporation        physical id: 0        bus info: pci@0000:03:00.0        version: a2        width: 64 bits        clock: 33MHz        capabilities: pm msi pciexpress bus_master cap_list        configuration: driver=nouveau latency=0        resources: irq:128 memory:a3000000-a3ffffff memory:90000000-9fffffff memory:a0000000-a1ffffff ioport:3000(size=128)  and : ubuntu@ubuntu:~$  cat /etc/os-release NAME=&quot;Ubuntu&quot; VERSION=&quot;18.04.3 LTS (Bionic Beaver)&quot; ID=ubuntu ID_LIKE=debian PRETTY_NAME=&quot;Ubuntu 18.04.3 LTS&quot; VERSION_ID=&quot;18.04&quot; HOME_URL=&quot;https://www.ubuntu.com/&quot; SUPPORT_URL=&quot;https://help.ubuntu.com/&quot; BUG_REPORT_URL=&quot;https://bugs.launchpad.net/ubuntu/&quot; PRIVACY_POLICY_URL=&quot;https://www.ubuntu.com/legal/terms-and-policies/privacy-policy&quot; VERSION_CODENAME=bionic UBUNTU_CODENAME=bionic  please consider the above three output has token form Ubuntu live flash system. What do you suggest and what do you think about reason of this failure? Also do you think it must be reported by me in ubuntu site, or it will be done automatically? Thanks. Uses of the definite article (the) in generic noun phrases I was reading a paragraph about lions and I came up with a question about the definite article (the).  Let me tell you first what I know about it.     1->We use the before a singular noun (when we are sure about the noun.    And the listener and the speaker both know about it).      2->We use the before a plural noun (again when we are sure about the noun,   and we are not talking generally).   So, my question is why does the writer use the here as we are not talking about any specific lion or lions. We are talking generally.  The Paragraph:     Living in the grasslands, scrub, and open woodlands of sub-Saharan   Africa, the lion is the second largest cat in the world. It is dwarfed   slightly by the tiger, which is closely related and has a very similar   body type.    Can we re-write the paragraph something like this:     Living in grasslands, scrub, and open woodlands of sub-Saharan Africa,   lions are the second largest cat in the world. They are dwarfed   slightly by tigers, they are closely related and has a very similar   body type. Status-* tags - moderator only? Why is . not in the path by default? On UNIX-like systems over the years (most relevantly to me, Linux), I've noticed that . (current dir) is never in the $PATH by default.  Why is this?  I recall reading years ago that it was a security problem, but the article I read didn't explain what exactly the problem was.  Is it because someone could leave a malicious version of ls or cp in a directory, and I'd end up running it without realizing it was there? A generic list of anonymous class If H is a subgroup of a group G and K is a normal subgroup of G the show that K is a normal subgroup of HK. Note K is a normal subgroup of HK  I thought I could just prove K is a subset of HK and vice versa so as to prove it a normal subgroup but then how to do this I have no idea because I keep getting hk element again while trying to do so.  I just tried to implement the steps to find HK is a subgroup of G. "'key' is not valid for passed 'access_token', token not found" when trying to login using Google on Android SE app I bought two pieces of land. One from Morthal, and one from Falkreath. Morthal was the first plot of land I purchased. I only finished half of it. I bought the plot of land in falkreath because I liked the nature better. I finished the house completely in Falkreath. Every time I try to adopt a child off the streets it keeps saying "I have a place but no room for you" Even though I have the bedrooms in my Falkreath house. Why can I not adopt a child and have him/her live at my house in Falkreath? In the construction of types of numbers, we have the following sequence:  $$\mathbb{R} \subset \mathbb{C} \subset \mathbb{H} \subset \mathbb{O} \subset \mathbb{S}$$  or:  $$2^0 \mathrm{-ions} \subset 2^1 \mathrm{-ions} \subset 2^2 \mathrm{-ions} \subset 2^3 \mathrm{-ions} \subset 2^4 \mathrm{-ions} $$  or:  "Reals" $\subset$ "Complex" $\subset$ "Quaternions" $\subset$ "Octonions" $\subset$ "Sedenions"  With the following "properties":   From $\mathbb{R}$ to $\mathbb{C}$ you gain "algebraic-closure"-ness (but you throw away ordering). From $\mathbb{C}$ to $\mathbb{H}$ we throw away commutativity. From $\mathbb{H}$ to $\mathbb{O}$ we throw away associativity. From $\mathbb{O}$ to $\mathbb{S}$ we throw away multiplicative normedness.   The question is, what lies on the right side of $\mathbb{S}$, and what do you lose when you go from $\mathbb{S}$ to one of these objects ? Can a multiclass character use either of its spellcasting modifiers for spells? How do I diff two text files in Windows Powershell? I have two text files and want to find the differences between them using Windows Powershell. Is there something similar to the Unix diff tool available? Or is there another other way I haven't considered?  I've tried compare-object, but get this cryptic output:  PS C:\&gt; compare-object one.txt two.txt  InputObject                                                 SideIndicator -----------                                                 ------------- two.txt                                                     =&gt; one.txt                                                     &lt;=