Computing Definition and 732 Threads

Below the error on photometric galaxy clustering under the form of covariance : $$ \Delta C_{i j}^{A B}(\ell)=\sqrt{\frac{2}{(2 \ell+1) f_{\mathrm{sky}} \Delta \ell}}\left[C_{i j}^{A B}(\ell)+N_{i j}^{A B}(\ell)\right] $$ where ##_{\text {sky }}## is the fraction of surveyed sky and ##A, B##...

Solution attempt: we make the substitution ##\frac{s}{2}=u## and ##ds=2du## to compute...

In a self learning project I am fooling around book https://faculty.washington.edu/rjl/fdmbook/ I want to do some of the computation myself to better understand the concepts but the book is Matlab based and Matlab is too expensive. Does anyone by any chance have some of the codes provided by...

Question: Diagram: So the common approach to this problem is using polar coordinates. The definition of infinitesimal rotational inertia at O is ##dI_O=r^2\sigma\, dA##. Therefore the r. inertia of the triangle is $$I_O=\int_{0}^{\pi/3}\int_{0}^{\sec\theta}r^2r\,drd\theta$$ whose value is...

I can't seem to understand how to solve this problem. Please help

I have a 2-dimensionsal smooth function ##f(x,y,t)##. There may be multiple traveling waves across the domain. None of them are precisely traveling waves (the shape of the wave changes as it travels). Here is how one of these waves would look in 1-dimension: I want to find the speed of these...

Hi. I have a collection of points in 3D space. I'm using MATLAB to find all pairs of points within a certain range from one another. Right now I'm using rangesearch(X,X,r), where X is the collection of points and r is the range. These points are the locations of atoms and I am attempting to...

Hi. I have graph which I am analyzing in MATLAB. I would like to determine sections of the graph which could be removed from the rest of the graph by removing only 2 edges. (The graph represents the network of atomic bonds from a simulation of silica, and I am attempting to locate strands of...

Hi. For some background, I am running molecular dynamics simulations of silica fracture in LAMMPS. Each point represents the location of a broken bond. I would like to find regions where many bonds are breaking, which I speculate would be locations of crack formation. These computations are...

Hi, Here is the question. Answer given is d. But i don't understand how is that computed? I am working on this question. Meanwhile any member knowing the correct answer may help me in finding out correct answer.

Hello, I was watching a video lecture from MIT 8.04 (Allan Adams)– lecture #24 (around the 38 minute mark give or take) The topic is quantum computing, Dr. Adams is deriving / explaining how to get various computing operations. For the “NOT” operation he explains that the operator $$ U_{Not}...

We know that the non-relativistic propagator describes the probability for a particle to go from one spatial point at certain time to a different one at a later time. I came across an expression (lecture notes) relating ##\Psi(x,t)##, an initial wave function and the propagator. Applying the...

Hi all. We are computing the second fundamental form corresponding to a surface. The correct answer should give the coefficients 2, 0, and -2 for IIuu, IIuv, IIvv We have only been able to compute IIz, and not IIx, IIy where we have functions instead of 2, 0 and -2. We are 99% certain that...

Hi! The topic is electrodynamic but it's a question about Nabla identity. Given $$ F = (p \cdot \nabla)E $$ How does one compute F? Is this correct? $$ F = \sum_{i} p_i \partial_{i} E_{i} e_{i} $$

Hi all Simple question: How I can compute the value of \(a = \sin \left( 2017 \sqrt[5]{2} \right) \) under following assumptions: No use of advanced numerical libraries is allowed. Only accepted operations are: comparisons, absolute value, addition, subtraction, multiplication and division...

Hi all, Checking my answers here as it doesn't seem to match with the answers given to me. Would appreciate if anyone could point out the mistakes I made. First I will compute Rth. Offing all independent sources, applying a known voltage across R (in this case 1v) and using mesh analysis...

Hi, I'm learning Reinforcement Learning, and computing q values is challenging. I'm not sure if the question wants me to follow this formula since I'm not given the learning rate \( \alpha \), and also because Q- Learning doesn't need a transition matrix. I'm really not sure where to begin...

h(x) = 0 for x ≤ 0 h(x) = x^2 for x>0 But my book says h(x) = 0 for x<0 h(x) = x^2 for x≥0 Can my solution (the first one) work as well? Because the actual function value at x = 0 is zero. I feel like my solution is more elegant.

I stumbled upon the following problem on instagram: $$L = \left (\frac{-1+i\sqrt{3}}{2}\right )^6+\left (\frac{-1-i\sqrt{3}}{2}\right )^6+\left (\frac{-1+i\sqrt{3}}{2}\right )^5+\left (\frac{-1-i\sqrt{3}}{2}\right )^5$$ The idea is to compute it. Using a calculator, it is supposed to equal 1. My...

I want to compute the Riemann Tensor of the following metric $$ds^2 = dr^2+(r^2+b^2)d \theta^2 +(r^2+b^2)\sin^2 \theta d \phi^2 -dt^2$$ Before going through it I'd like to try to predict how many non-trivial components we'd expect to get, based on the Riemann tensor basic rule: It is...

Properties 1) If ##(\gamma^{\alpha}\gamma^{\beta}...\gamma^{\mu}\gamma^{\nu})## contains an odd number of ##\gamma##-matrices $$Tr(\gamma^{\alpha}\gamma^{\beta}...\gamma^{\mu}\gamma^{\nu})=0$$ 2) $$Tr(\not{\!A}\not{\!B})=4AB$$ 3) $$Tr(\not{\!A}\not{\!B}\not{\!C}\not{\!D})=4\Big(...

I've been studying different scattering processes (from Mandl & Shaw QFT's book, chapter 8) and there's always a common step I do not understand: the showing-up of the trace. Let me give two specific examples. Lepton Pair Production ##( e^+ (\vec p_1, r_1) + e^- (\vec p_2, r_2) \rightarrow l^+...

To elaborate a little on what I think I do understand / accept: 1. I don't think I have a problem accepting the "weirdness" of quantum concepts. So, for example, I am willing to accept the concept that a quantum system can "exist" in a large number of different states simultaneously. 2. I...

Hello I am trying to choose a school and am interested in quantum computing theory in the physics department. I haven't decided whether or not I want to stay in academia so I would like the option to go into industry maybe at Google, IBM or a startup. Ideally I'd like the reputation/research to...

During a quantum computation, all possible solutions exist in a state of superposition. How is the relevant one selected?

The book's procedure for the "shooting method" The point of this program is to compute a wave function and to try and home in on the ground eigenvalue energy, which i should expect pi^2 / 8 = 1.2337... This is my program (written in python) import matplotlib.pyplot as plt import numpy as...

Hi guys, I am an absolute beginner in quantum computing. I am really curious about its mechanics but my lack of knowledge in mathematics makes me struggle. I cannot entirely understand why numbers |1> cancel each other out while double Hadamard gates are applied. If the rule is to cancel out the...

REMARK: First of all I have to say that this Lagrangian reminds me of the Lagrangian from which we can derive Maxwell's equations, which is (reference: Tong QFT lecture notes, equation 1.18; I have attached the PDF). $$\mathcal{L} = -\frac 1 2 (\partial_{\mu} A_{\nu} )(\partial^{\mu} A^{\nu}) +...

Good Morning I have googled this issue (the difference between Grid and Cloud computing, as per subject line), but I find many of the definitions overlap each other and leave a lot of ambiguity. A lot of the examples focus on manipulation of data (versus independent processes). But BEFORE I...

I need to apply, with CAMB code, a correction on ##\sigma_{8}## between linear and non-linear regime to keep it fixed (I make change the values of cosmological parameters at each iteration). I have to compute ##\sigma_{8}## from the ##P_{k}## and found the following relation (I put also the text...

The arrival of quantum computing reminds me of "the manhattan project" and "the sputnik alert" when physicists are highly demanded. And this makes me wonder if the age of quantum computing means the better future for physicists since the development of quantum computers needs at least...

The formula for the Damping Tail in the CMB BAO analysis generally has the form: $$\mathcal{D} (k)=\int_{0}^{\eta_0}\dot\tau e^{-\left[\frac {k}{k_D(\eta)} \right]^2}d\eta $$I can’t make sense of this. ##\dot\tau## is the Thompson (Differential) Opacity; the product of electron density, cross...

Hello dear friends, I need your help with this probability problem. I have random variable x1 which is normally distributed with mean m1 and standard deviation sigma1. The vector of random variables X0 is of N elements, where each element is normally distributed with zero mean and standard...

In this clip www.youtube.com/watch?v=ZGtUGuAY63E&t=25s starting from 00:25, the engine comes to a stop and reverses. If you watch the boiler, you see that it appears to bend under its own inertia like the boiler on a cartoon engine might when reversing in a hurry. If you play that again and...

I would like to compute the triple integral of a function of three variables $f(x,y,z)$in R. I am using the package Cubature, Base, SimplicialCubature and the function adaptIntegrate(), Integrate and adaptIntegrateSimplex(). The integrand is equal to 1 only in certain domain(x<y<z, 0 otherwise)...

This is a hypothetical question, but.. How much computing power would all the computers in the world combined have? Would you have a at least one YottaFLOP?

Assume ##P_1## and ##P_2## are two projection operators. I want to show that if their commutator ##[P_1,P_2]=0##, then their product ##P_1P_2## is also a projection operator. My first idea was: $$P_1=|u_1\rangle\langle u_1|, P_2=|u_2\rangle\langle u_2|$$ $$P_1P_2= |u_1\rangle\langle...

Two KL functions $f_1:\mathbb{R}^n\rightarrow \mathbb{R}$ and $f_2:\mathbb{R}^n\rightarrow \mathbb{R}$ are given which have KL exponent $\alpha_1$ and $\alpha_2$. What is the KL exponent of $f_1+f_2$?

What sensor to would i use to measure the difference in wave length periods. I want to make a rendered image of somthing that field of view that is being obstructed.

This is an exercise from "Quantum search as a quantum simulation " in Chapter "Quantum search algorithms". The circuit is shown as the following picture. For small time interval, the effect of the operation in the problem statement could be written as ## exp \left ( -i \left | \psi \right >...

Problem Statement: Computing AC voltage Relevant Equations: cut off frequency, ac voltage. Hey guys, Amazing to be in this group ! Please find attached the diagram of the problem. E = 10kV at 60Hz, C1 = 60pF and R1 = 1k. I have to compute the ac voltage in reference to ground at point [1]...

I am confused about the vector notation of quantum states when I have a 2 qubit system. For 1 qubit, I just write l1> = (0 ;1 ) for representing 1, and l0> = (1;0) for representing 0. Dirac notation is straightforward However when it comes to representing two qubits in linear algebra I...

My project for obtaining my master's degree in computer science involved ray tracing in Schwarzschild spacetime in order to render images of black holes. These light rays had to be computed numerically using the geodesic equation. However, I ran into a problem. The geodesic equation is given as...

Suppose p(λ)=(λ-1)^3 for some diagonalizable matrix A. Calculate A^25. I'm confused as to how to approach this question without A being given. I thought perhaps I could use the characteristic equation in some way although I am still unsure. I think I could start with using λ=1. Would my...

I have computed the total length of a 3D triangle and its area. The code is shown below. I want to use file output instead of cout. The file name, cw2task1output, was just given as part of the task, in this case should I make an empty text file named cw2task1output then attach it to the resource...

Homework Statement I have successfully opened and discarded the headers. Then I calculated the distances between point 1 and others and the minimum distance as well. However, I am not sure how to make the code work for more than 4 points. The attached text file is what I am trying to read and...

Homework Statement Homework Equations $$F = \nabla \phi$$ $$| F | = \sqrt{F \cdot F}$$The Attempt at a Solution I want to compute ##| F | = \sqrt{F \cdot F}## $$| F | = \sqrt{F \cdot F} = \sqrt{\frac{(km)^2 (r-r_0)^2}{|r-r_0|^6}} = \sqrt{\frac{(km)^2}{(r-r_0)}} =...

Hi everyone, I'm a computer scientist (not a physicist), so I will ask a computer scientist's question. In all the descriptions I found of Grover's algorithm, there is an element that is puzzling the computer scientist in me: it seems that you need to tell the Oracle about the position of the...

Homework Statement Compute ##S(n,3)##. Homework EquationsThe Attempt at a Solution To compute this I used the fact that ##S(n,2) = 2^{n-1}-1## and used the recurrence relation ##S(n,k) = kS(n-1,k) + S(n-1,k-1)##, and used induction to get that ##S(n,3)=\frac{3^{n-1}+1}{2}-2^{n-1}##. But is...