Search Results
Search type | Search syntax |
---|---|
Tags | [tag] |
Exact | "words here" |
Author |
user:1234 user:me (yours) |
Score |
score:3 (3+) score:0 (none) |
Answers |
answers:3 (3+) answers:0 (none) isaccepted:yes hasaccepted:no inquestion:1234 |
Views | views:250 |
Code | code:"if (foo != bar)" |
Sections |
title:apples body:"apples oranges" |
URL | url:"*.example.com" |
Saves | in:saves |
Status |
closed:yes duplicate:no migrated:no wiki:no |
Types |
is:question is:answer |
Exclude |
-[tag] -apples |
For more details on advanced search visit our help page |
For questions about problems related to physics that involve evaluating integrals. Purely mathematical questions should be asked at math.SE.
1
vote
Accepted
How to compute this form factor?
You can use the fact
$$
\int e^{-iqr \cos\theta} \sin \theta d\theta = -\int e^{-iqr c} dc
$$
where $c$ is the integration variable that replaced $\cos\theta$. The integral is now elementary. …
2
votes
Accepted
Probability density function (pdf) of a Wiener process
Given the normally distributed random variable $Z\sim {N}(\mu,\sigma^2)$, it is possible to show that its moment-generating function is
$$\langle \exp({tZ})\rangle=\exp({\mu t + \sigma^2 t^2/2})=\exp …
14
votes
Why aren't Runge-Kutta methods used for molecular dynamics simulations?
In molecular dynamics you have to evolve a large number of particles, so efficiency is important. The Verlet algorithm provides numerical stability, as well as other properties that are important in …
23
votes
Accepted
If charges is quantised, how can we use integrals in electrostatics?
You may also wonder why we use the concept of density of a material despite that material is made of molecules, or atoms, or in general quantized entities. This is the basis of hydrodynamics and solid …
2
votes
Complex coordinates $ds^2 = dzdz̄$ in 2d
Consider $z=x+i y$ and $\bar z=x-iy$ ($x$ and $y$ are real). It is easy to show that:
$$
dz\land d\bar z=(dx+i\,dy)\land(dx-i\,dy)
=dx\land dx+i \, dy\land dx
-i \, dx\land dy-dy\land dy.
$$
However, …