What is Computing: Definition and 730 Discussions

Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both hardware and software. It has scientific, engineering, mathematical, technological and social aspects. Major computing disciplines include computer engineering, computer science, cybersecurity, data science, information systems, information technology and software engineering.

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  1. L

    High permormance symbolic computing

    Dear all, I have derived a set of differential equations. One is still missing and its left hand side is called f (as in the attachment). Unfortunately f is known only implicitly. I am not very familiar with maple or mathematica. My question is: Is it possible to obtain the expression...
  2. P

    How far is quantum computing from reality?

    When will quantum computers become useful? For example, cracking some real-world encryption, simulating quantum behaviour of molecules, or enhancing web search engines? I somehow have the impression that this is a field of physics where theorists keep dreaming and experimentalists keep playing...
  3. A

    Computing the action for a particle in a gravitational field

    A friend of mine told me he fielded this at an oral exam: "Compute the classical action S for a particle of mass m in a gravitational field U = -\alpha/r." I know the formula for the classical action is given by S = \int_{t_i}^{t_f} L(q,\dot q,t) dt, and that for a particle in a...
  4. S

    Programs Parallel computing for PhD in Computational Astrophysics

    Hi, I wanted to know if someone who has a degree in parallel computing and related work experience will be able to get a PhD project in Computational Astrophysics? What other skill sets would the person require? I have seen many PhD positions that accept people from a parallel computing...
  5. N

    Interested in Quantum Computing

    Hi, I'm a second year physics major with specialization in computational physics, and I have recently become interested in quantum computing, and stuff dealing with computers like the memory cell nanoribbons made of graphene. I wanted know if I am currently pursing the best degree to get...
  6. jegues

    Computing true percent relative error (Taylor Series)

    Homework Statement See figure attached, Homework Equations The Attempt at a Solution Isn't the Maclaurin series just simply the Taylor series around 0? (\text{i.e. } (x-c), \quad c=0, \quad x ) Also for part B, how do we go about solving for | \epsilon_{t} |? Thanks...
  7. A

    Computing Inner Products of Vectors: a,b,c,d,e,f

    Hi everyone, I need help with this problem. I just can't get it: Let a,b,c,d,e and f be vectors such that \langle a,b \rangle=-4, \quad \langle a,c \rangle=-9, \quad \langle b,c \rangle=2, \quad b+c=d, \quad -4 a+3 b=e and -4 b+5 c=f. Compute the following inner products: \langle b,a...
  8. B

    Calculating n with Super-Fast Computing: P1-P4

    • P1 takes n days to run • P2 takes n^2 days to run • P3 takes 2^n days to run • P4 takes log(n) in base 2 days to run So, to run P2 on an n of 4 would take 16 days. a. For each version of the program, calculate the value of n (rounded down) we could compute if we let the program run for...
  9. J

    Calculating Comutator of H and 1/r∙r

    I need to calculate \left[ H , \ \frac{1}{r} \mathbf{r} \right] . My initial idea is to use \left[ H, \ U \mathbf{r} \right] = \left[ H, \ U \right] \mathbf{r} + U \left[ H , \ \mathbf{r} \right] . Then clearly \left[H , \ U \right] \psi = \frac{ - \hbar ^{2} }{2m} \left( \nabla ^{2}...
  10. J

    Trapped Ion Computing Question

    Hi all, I have a question about trapped ion. How can they achieve such stable frequencies if the power supply which supply's the ion trap drifts over time? For example if you use a paul trap as an atomic clock, how do you compensate for any fluctuations in power supply voltage and frequency?
  11. M

    Fast Computation of Fundamental Groups: Practical Methods and Tricks

    So I've read through beginning alg topology really fast and there are a lot of theorems and methods for computing fundamental groups but what are the most useful tools? When asked to compute the fundamental group what should one do? try to find a deformation retract and compute the fund group...
  12. M

    IBM's breakthrough chip technology lights the path to exascale computing

    http://www.physorg.com/news/2010-12-ibm-breakthrough-chip-technology-path.html Can Microsoft or AMD use this Nanophotonics chip technology? Can they say goodbye to Moore's Law after this breakthrough?
  13. D

    Lambert's Cosine Law, Computing Diffuse Reflection

    Lambert's Cosine Law, Computing Diffuse Reflection : I have 2 coordinates (5, 6, 0) the light source and (2.3, 1.92, 0) the plane. The diffuse coefficient is 0.6 and the light source intensity is 200. So using the Lambert's Cosine Law, I need to take 0.6 * 200 * the dot product of the...
  14. N

    Computing harmonic oscillator propagator via path integral

    Homework Statement Show that G(q_2,q_1;t)=\mathcal{N}\frac{e^{iS_{lc}}}{\sqrt{\det A}} where \mathcal{N} is a normalization factor independent of q1, q2, t, and w. Using the known case of w=0, write a formula for G such that there is no unknown normalization factor. Homework Equations I...
  15. S

    Computing Matrix, finding kernel and image

    Let T: R[x]2\rightarrow R[x]3 be defined by T(P(x))=xP(x). Compute the matrix of x with respect to bases {1,x,x2} and {1,x,x2,x3}. Find the kernel and image of T. I know how to do this when given bases without exponents, however I do not know exactly what this is saying and therefore am...
  16. C

    Quantum Computing Books: What to Read After Graduation

    I'm a third year physics student and just wanted to know for the future, what books should I get in order to learn more about Quantum Computing (theory behind it)? I know Quantum Mechanics books, yes, but what else like after graduation? Thanks so much! So far on my list is just books on...
  17. S

    Help with computing density of one variable change.

    Let X have density function fx(x)=1/x^2 for x>1, otherwise fx(x)=0. Let Y=X^(1/3). Compute the density function fy(y) for Y. my attempt ------------ P(X<=1)=0 P(Y^3<=1)=P(Y<=1)=0 P(1<x<inf)=P(1<Y^3<inf) =1-P(Y<1) i am stuck here. The answer to this is fy(y) = 3y^4 for y>1 and...
  18. Z

    Why is entanglement essential for quantum computing?

    Asked myself that question today, and I don't know what the answer is. Maybe I missed something somewhere in the math... Anyone know?
  19. H

    Method of Indicators for computing expectation

    Hi, I have the following problem: Suppose you have a coin that has chance p of landing heads. Suppose you flip the coin n times and let X denote the number of 'head runs' in n flips. A 'head run' is defined as any sequence of heads. For example the sequence HHTHHHHHTTTTHHTHT contains 4 head...
  20. N

    Quantum Computing: Learn More & Find Answers

    I have some questions about the very new and theoretical field of quantum computing and would love to learn more. Is, or are there any good informational places where I can learn more? I have already looked at the wikipedia page but it simply left me in wanting.
  21. B

    Computing Scalar Product in Antisymmetric Fock Space w/ Creator Operators

    We use the antisymmetric Fock space ( "fermions"). We denote by c(h) a creator operator. I need to evaluate the following quantity: < \Omega , \big(c(h_1)+c(h_1)^{*}\big)\big(c(h_2)+c(h_2)^{*}\big) \ldots \big(c(h_n)+c(h_n)^*\big)\Omega> where \Omega is the unit vector called vaccum...
  22. P

    Computing the value of an integral from Apostol I

    Homework Statement The notation [x] denotes the greatest integer <= x "integral sign" with a lower limit of -1 and a upper limit of 3 [x] dx Homework Equations I would like to know how to enter symbols for certain problems. I am lost when Apostol says "the notation [x] denotes the...
  23. D

    Computing the Jacobian matrix for a solar system simulation

    Hello physicists! I'm a comp sci student and I am trying to graphically model a simplified version of the solar system as part of a programming exercise. In order to apply the gravitational forces to the planets, I need to compute the Jacobian matrix as it relates to two particles (planetary...
  24. K

    Computing vacuum expectation values

    I have small question computing vacuum expectation values here http://www.cns.gatech.edu/FieldTheory/extras/SrednickiQFT03.pdf" from Mark Srednicki. My problem is with equation 210 on the pdf page 69. In the second line of 210, where does the second term come from? Z(J) and W(J) are defined...
  25. jinksys

    Computing eigenvalues and eigenvectors

    Find the characteristic polynomial, eigenvectors, and eigenvalues of the matrix. [ 2 -2 3 0 3 -2 0 -1 2 ] My characteristic poly is x^3 - 7x^2 + 14x - 8 The roots are 1, 2, and 4. When solving the system, (2I - A)x = 0 I get: [ 0 1 0 0 0 0 1 0 0 0 0 0 ] Can...
  26. D

    Quantum Computing and Entanglement

    Hello people of physics I am writing a paper for an undergraduate quantum mechanics course (my second quantum course) on the following topic The role of entanglement in quantum computing Just wondering if somebody could recommend a good paper or a good book on this topic. Any suggestions...
  27. P

    Velocity of Particles in Quantum Mechanics: Momentum & Computing Mean Values

    How do we define veliocity of a particle in QM? How it's related to the momentum. Are there any ways to cimpute quickly mean value of veliocity.
  28. S

    Fortran Fortran 2008: The Final Steps of Standardization for Scientific Computing

    http://www.nag.co.uk/sc22wg5/ It looks like Fortran 2008 is going through its final steps of standardization. What does this mean for scientific computing? Since people still use Fortran 90 despite new revisions up to 2003, will this go under the radar, or will this be a new and useful...
  29. stripes

    Computing an improper integral

    Homework Statement \int^{1}_{0}\frac{dx}{\sqrt{1-x^{2}}} Homework Equations None The Attempt at a Solution \int^{1}_{0}\frac{dx}{\sqrt{1-x^{2}}} = sin^{-1}x\right|^{1}_{0} sin^{-1}x\right|^{1}_{0} = \frac{\pi}{2} - 0 so the final answer is just pi/2. I have no problem computing the...
  30. D

    Dan Sandberg - Quantum Computing & Phys. Chem. @ UConn USA

    Hi All - My name is Dan Sandberg and I am studying physical chemistry at the Univ. of Connecticut in the USA. I recently heard a talk on quantum computing and, at the time, began to picture a quantum computer which employed a photoactive protein. I decided to attempt to see this idea to...
  31. J

    Computing Beam Deflection Using Castiglianos' Theorem

    I am trying to find the deflection of the beam as described below, The beam has an overall length L and a load Q acting downwards at this point, the question is asking for the deflection of the beam at the point three quarters of the way along the beam. The beam has constant flexural rigidity...
  32. J

    Computing ∂f/∂x (0,0) | Midterm Review Sheet Problem 2(a)

    Homework Statement This is problem 2(a) from my midterm review sheet, found here: http://www.math.washington.edu/~sullivan/326smt_sp10.pdf Homework Equations Not sure what exactly I need here The Attempt at a Solution By the quotient rule, ∂f/∂x =...
  33. C

    Simpson's Method for Computing Relative Error of x

    I want to compute x within 0.1% relative error with Simpson method, these are my m-files. Which command i should add for this? function simps(a, b, n) %simps(a, b, n) approximates the integral of a function f(x) in the %interval [a;b] by the composite simpson rule %n is the number of...
  34. rhody

    Stephen Wolfram: Computing a theory of everything TED Video April 2010

    Thought you might like this... This http://www.ted.com/talks/stephen_wolfram_computing_a_theory_of_everything.html?utm_source=newsletter_weekly_2010-04-27&utm_campaign=newsletter_weekly&utm_medium=email" by Stephen Wolfram is about 20 minutes long, but the most interesting parts are from...
  35. S

    Computing Meteor Trajectory from Data for Two Stations?

    I'd like to compute a meteor trajectory from data gathered by two video camera. One method I've recently considered but do not know much about it is to treat the meteor as an Earth satellite in a circular orbit. Once a great circle plane is found, then one could produce a ground track by...
  36. C

    New extremely simple method for computing extremely complicated integrals

    http://arxiv.org/abs/0812.3356 http://arxiv.org/abs/1004.2062
  37. O

    Courses Courses in Quantum Computing at Waterloo, IQC & Perimeter

    Hey , I want to know about the courses in quantum computing at univ. of waterloo or IQC or perimiter institure for international students and also the procedure and other formalities to apply there??I have done masters in physics and currently having a 2 year IT exp. under my belt. i want...
  38. K

    Computing Fourier Series for a Piecewise Function

    Homework Statement Find the Fourier series for y(x)=\begin{cases} A\sin(\frac{2\pi x}{L}) & 0\leq x\leq\frac{L}{2}\\ 0 & \frac{L}{2}\leq x\leq L\end{cases}Homework Equations B_{n}=\frac{2}{L}\int_{0}^{L}y(x)\sin(\frac{n\pi x}{L})dxThe Attempt at a Solution...
  39. S

    Computing impulse response (help)

    I am trying to find the impulse response h[n] of a LSI system: y[n]+ay[n-1]=bx[n]-cx[n-1]. The way that I think to solve this problem is compute the z-transform, and from this H(z)=Y(z)/X(z). Then take the inverse z-transform to find h[n]. Is there another way to compute this? Also, for H(z)...
  40. P

    What is slowness of the sun in computing azimuth angle?

    what is "slowness of the sun" in computing azimuth angle? Homework Statement The question is to calculate the azimuth angle for a city and to use the analemma diagram to estimate the "slowness of the sun." Homework Equations The Attempt at a Solution I need to know what slowness...
  41. M

    Is There a Cure for Computing Phobia?

    I've noticed more and more that I go to absurd lengths to avoid computing things. Everything from finding derivatives to solving integrals to simplifying expressions I've been doing on a computer for the past couple of years, and it's gotten so bad that I don't even attempt to do the...
  42. L

    Maple Computing Inner Product of f_1 Using Maple Procedure

    so I'm writing a maple procedure for the variational principle in quantum mechanics. i have a function f_1(x,\alpha)=\cos{\alpha x} for |x| \leq \frac{\pi}{2 \alpha} and i need to compute \left \langle f_1 | f_1 \right \rangle i have the code: restart; assume(x,real)...
  43. S

    Can a CNOT Gate Alone Create a Toffoli Gate?

    Homework Statement I'm trying to show that controlled-not gate can not be used to make toffolit gate(controlled-controlled not gate) Homework Equations The Attempt at a Solution i'm thinking that controlled not only has +(addition modulo 2) of the inputs, it can't make X and Y for...
  44. S

    Learn Quantum Computing: Physics, Math & Theory Basics

    I know this is a rather new field of research and that I may seem rather silly for asking, but I would like to know besides upper divison undergrad quantum mechanics ( which I've already studied ), what other subjects should I learn to get the basic background for researching quantum computers...
  45. 1

    What is a Qubit in Quantum Computing?

    Can someone give me a layman's explanation for the Qubit? And, like the bit, does it represent an intangible, or does it have some material quality to it?
  46. S

    Getting into research Quantum computing

    I wanted to get into research and so far it seems like a fairly easy process. I want to delve into the world of quantum computing, but unfortunately there are currently no professors at my school who research that topic. So I wanted to start my own research team with a professor and find a way...
  47. R

    Computing a double integral with given vertices

    1. Homework Statement [/b] Use the transformation that takes the unit square to a triangle to compute the integral \int\int_{B}2x+3y dA Where B is a triangular region with vertices (0,0), (5,2), and (3,4). The Attempt at a Solution What I did was I drew the region on an xy...
  48. G

    Computing Flight Forces. Im getting so upset

    Hi, ok.. i know I am probably expecting way to much off you guys here but its my only last resort before i give up! Ill explain.. I am a avid aviation fan as well as an avid game developer whilst also being a fulltime software developer. So i program in delphi at work and what i want as a...
  49. L

    Quantum computing (Why is it important?)

    Alright, I'm just getting my feet wet in the world of physics, but, I've taken a particular interest in quantum mechanics/physics. And, my first question is, what is the point of quantum computing? It's my understanding (Though it's probably seriously flawed) that quantum computations are used...
  50. Somefantastik

    Integrating over Triangle C: Computing Normal Vector

    Homework Statement C is triangle (0,0), (4,0), (0,3). R is the enclosed region. Compute the following integral, where n is the outward pointing normal: \int_{C} \left(4x-y^{2}\right)n^{1}ds where n^{1} = \widehat{i} \cdot \widehat{n} Homework Equations The Attempt at a...
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