# What is Computation: Definition and 246 Discussions

Computation is any type of calculation that includes both arithmetical and non-arithmetical steps and which follows a well-defined model (e.g. an algorithm).
Mechanical or electronic devices (or, historically, people) that perform computations are known as computers. An especially well-known discipline of the study of computation is computer science.

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1. ### I Ontology is to quantum theory what hardware is to computation theory

In interpretations of quantum mechanics there are two types of physicists: those who care about ontology and those who don't. The ontologists, or realists, want to know what is the world made of. The non-realists, on the other hand, think that this question is not relevant to physics. Usually...
2. ### Cubical Pressure Vessel - Maximum Pressure Computation

Hello everyone - this is my first post on the forum and this would be for a real world application. I have no mechanical engineering experience. We plan to build a cubical aluminium (6082 grade) pressure vessel. The total external dimensions are 540mm x 400mm x 75mm. The aluminium wall...
3. ### App that converts a checklist to a text

Hi, I am looking for an app that converts a checklist to text. The advantage of this app is to save time in writing professional reports. For example, suppose a professional uses a list of 10 possible variables to examine a case but finds only 4 variables match a pre-set quality criteria. In...
4. ### Comp Sci Regular Expression in Theory of Automata and Computation

In first part,since every block of 4 consecutive symbol contain at least 2 a's The answer in notes is given (aa(a+b)(a+b)+a(a+b)a(a+b)+a(a+b)(a+b)a+(a+b)aa(a+b)+(a+b)a(a+b)a+(a+b)(a+b)aa)+ But this wont be true since if we choose aabbbbaa which is possible according to the above regular...
5. ### AI Computation (self study analysis, pointers welcome)

In this thread I attempt to find a closed form solution to the gradient descent problem for a single sigmoid neuron using basic calculus. If you would like to give pointers feel free, if you see me make a mistake please let me know! Thank you!
6. ### I Counterfactual quantum computation on interferometer

I watched a video on the topic by Sabine Hossenfelder. Now it is said by many that this proves the photon "knows" something in advance because a certain state of a certain beam splitter can be probed in theory without the photon ever encountering that beam splitter because it took another path...
7. ### I Quantum computation and entropy

Quantum gates must be reversible. The usual justification for this is that in QM the time evolution of a system is a unitary operator which, by linear algebra, is reversible (invertible). But I am trying to get a better intuition of this, so I came up with the following explanation: In order to...
8. ### Preparing for a Quantum Computation Course: Superconducting Qubits

Summary:: Looking for articles/books to prepare myself for the course: Quantum computation with superconducting qubits Hello everyone. I am about to take a course in Quantum computation with superconducting qubits and I am searching for material to prepare it. I took a first course on that...
9. ### I Question regarding actual computation of tensor at point (Self Study)

Hello all, I am hoping to get some feedback on the manner in which I performed computations towards solving the following problem. There are a couple specific points which I am not confident of: 1. Did I properly account for the manifold structure in my computation of the nonzero components...
10. ### Numerical computation of the derivative

I'm not sure if this is the correct forum to post this question, or should I post it in a math forum. But I was looking at some code when I found a 'strange' implementation to compute the derivative of a function, and I wanted to know if any of you has an idea of why such an implementation is...
11. ### Comp Sci DFA that accepts either ab or ba as substring?

Attempt at solution-: Now this dfa will also accept abba which in my inituition it should not accept. But it does accept it. What is going here? Please guide
12. ### I A computation of an integral on page 344 of Schutz's textbook

On page 344 of "A First Course in GR" he writes the following: When I do the integration I get the following: ##\int_0^{\chi^2}d\chi^2= \int_0^{r^2}\frac{dr^2}{1-r^2}= \chi^2 = -\ln (1-r^2)##, after I invert the last relation I get: ##r=\sqrt{1-\exp(-\chi^2)}##, where did I go wrong in my...
13. ### Courses Learning Parallel Computation as a particle physicist

I am starting my Master's Degree in Nuclear and Particle Physics, should i invest in taking a course in Parallel Computation? I know the role that Parallel Computation has in particle physics, but is there any use in a particle physicst learning about parallel computation, or could it be...
14. ### Neutron quantity normalization in an eigenvalue computation

Dear Community, I am having a question. I have developed a simple code to perform iteration power algorithm and find the keff value of a system. However, it is not still totally clear in my mind if I have to normalize all my scores by the eigenvalue, i.e. multiply by the keff (fluxes, power...
15. ### I Computing the Speed of Traveling Waves in 2 Dimensions

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...
16. ### I Computing the Density of a Point Cloud

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...
17. ### A Can Data Travel Faster Than Light Computation?

Hi bear with me I have a conundrum I want to ask you. If data traveled many times the speed of light could the results of decrypted cypher message be computed quicker than any system we currently have? For instance if we sent a burst of data at many times the speed of light across the solar...
18. ### MHB Computation of the ratio of barometric pressure

Hi, The Homestake gold mine near Lead,South Dakota is excavated to 8000 feet below the surface. Lead is nearly a mile high; the bottom of the Homestake is about 900 m below sea level. Nearby custer peak is about 2100 m above sea level. What is the ratio of barometric pressure on the top of the...
19. ### Problem in solving differential equation

Hello everyone! I was studying chaotic systems and therefore made some computer simulations in python. I simulated the driven damped anhatmonic oscillator. The problem I am facing is with solving the differential equation for t=0s-200s. I used numpy.linspace(0,200,timesteps) for generate a time...
20. ### MHB Computation of bond angles and other angles in tetrahedral

Hello, I didn't understand the geometry of molecules in which central atom has no lone pairs of electrons. for example, in $CH_4, NH_4^+$ molecular shape is tetrahedral and bond angle is $109.5^\circ$. How is that bond angle computed? $CH_4$ stands for liquid methane and $NH_4^+$ is a...
21. ### Quantum Which books are good for learning spectrum computation?

Hello everyone. I 'd like to learn how to calculate the spectrum for elements. Which books are recommended?
22. ### Are there articles on Classical computation of the Photoelectric Effect?

photoelectric effect is now explained in quantum idea. Why the classical model fails? Are there articles computing it in detail using classical model?
23. ### I Rewriting a complex number for use in an analytic computation

Consider an equation, $$\tilde{x_0} = \ln(X+ i\delta),$$ where X may be positive or negative and ##0< \delta \ll 1##. Now, if ##X>0## this evaluates to ##\ln(X)## in some limiting prescription for ##\delta \rightarrow 0## while if ##X<0##, we get ##\ln(-X) + i \pi. ## Now, consider...
24. ### B Does the Feynman diagram process actually exist, or is it just for computation?

i want to known whether virtual particle exist or not , and does exchange of particle really happen in interaction.
25. ### B Quantum Computation notation

Hi guys, I am currently having some difficulties with this quantum state. I don't entirely understand what that letter 'i' means, where it comes from and why it appears in brackets [1, i]. Shouldn't there be a '0' instead? I am an absolute beginner in quantum computation. I've been following a...
26. ### Trouble with Electric Potential Boundaries (Computational Physics)

This is in python: #ELECTRIC POTENTIAL from mpl_toolkits.mplot3d import Axes3D from matplotlib import cm import numpy as np import matplotlib.pyplot as plt dx = 0.1 dy = 0.1 xrange=np.arange(-1,1,dx) yrange=np.arange(-1,1,dy) X,Y = np.meshgrid(xrange, yrange) max_dV = 10e-5 blockRadius = 3...
27. ### Programs Quantum Computation and Information Master's Degree

I'm in a Physics BSc programme and I would like to delve into quantum computation and quantum information. There are two master's degree in Europe that I find interesting in particular: Quantum Engineering MSc at ETH Zurich and Applied Physics MSc at TU Delft (track in Quantum Devices and...
28. ### MHB Computation based on linear growth

In 2000 the company had 300 customers. In 2015, this company already had 1200 customers. How many customers did the company have in 2008 if we know that the number of customers growing is linear?Just want to make sure, is 780 the correct answer?
29. ### Chemistry Computation of Liquid/Vapor Result during a Volume Expansion

I am searching for the appropriate methodology/equation(s) to step beyond Boyle's Law to account for the phase change and solve this problem. All suggestions/guidance is greatly appreciated! Bruce
30. ### Studying Value of learning the Theory of Computation and Automata

This may be a somewhat disorderly, unplanned out question, but nonetheless, I don’t know whether or not there exist any suitable academic advising websites that would be suitable for posting such. Would it be worthwhile investing time into learning theory of computation and automata via Neso...
31. ### I Confusion about factoring in quantum computation

Hi, I'm currently learning QC with Nielsen's QCQI. I've written a program in Matlab following the factoring algorithm in page 233 and 235. I run the program for factoring 15, 18, and 25. I got the proper results several times, but I also got error reports sometime, especially when factoring 18...

45. ### A Reducing computation for large power sets

To illustrate my problem say I have the following table: Option, x , y A , 25 , 30 B , 5 , 12 C , 3 , 9 D, 12, 13 I want to create a graph of every possible combination in the set where the x values are added and the y values are added. For example say it was...
46. ### Computation of Thevenin Equivalent

Hello! Recently I was going through some old exams and upon encountering this problem (which seemed pretty easy) I got stuck. Exams at my university are composed of individual tasks, each having three subquestions with four plausible answers respectively. Solution sheet gives results only, so...
47. M

### Mathematica Mathematica Computation Time

Hi PF! I am using the following code in Mathematica mat = {{1, Cos[2], Cos[4], Sin[2], Sin[4}, {1, 1, 1, 0, 0}}; Li[x_] := Transpose[ NullSpace[ mat].{{1}, {Cos[x}, {Cos[ 2 x]}, {Sin[x]}, {Sin[2 x]}}]; Li1[x_] := Li[x].{{1}, {0}, {0}}; f[x_] :=...
48. ### QFT Klein Gordon Theory, momentum commutator computation

Homework Statement Homework EquationsThe Attempt at a Solution [/B] I think I understand part b) . The idea is to move the operator that annihilates to the RHS via the commutator relation. However I can't seem to get part a. I have: ## [ P^u, P^v]= \int \int \frac{1}{(2\pi)^6} d^3k d^3 k'...
49. ### Computation of maximum pressure in heated closed vessel

I have a relatively simple design problem but my memories of thermodynamics are very rusty and I can't figure it out on my own. To make it short, I want to put a mix of solid, water and air in a 500mL pressure vessel and heat it all up to 250'C for several weeks. T and P are at room conditions...
50. ### Magnetic Field Computation from Thick Rectangular Conductor

Hello, and thanks in advance for taking a look at my question. Generally, I am trying to make a railgun force model. Since railguns depend on the magnetic field created around the rails (and the resulting Lorentz force) I need to model the magnetic field created by the current that flows...