# Search results

1. ### Photon/particle's energy in General Relativity

Hi everybody! I am wondering, among other things, whether the Special Relativity relationship E = p for a photon (I am using c = 1 units ) is still valid in General Relativity. Let me explain my question in detail. By applying the null geodesic condition with a diagonal metric, we obtain...
2. ### Roundoff error - double precision is not enough

Hi everybody! I kindly request your help. I have to compute functions like \frac{ \sin (r x) - r x \cos (r x)}{r^3} (primitive function of x sin(rx) ) or \frac{ -r x (120 - 20 r^2 x^2 + r^4 x^4) cos(r x) + 5 (24 - 12 r^2 x^2 + r^4 x^4) \sin(r x)}{r^7} (primitive function of x^5 sin(rx) )...
3. ### Numerical integration - Fourier transform or brute force?

Hi everybody! I kindly request your help in optimizing the numerical integration of the following expression: \xi (r)=\frac{1}{2\pi ^2}\int_{-\infty}^{\infty}f(k)\cdot \sin(k\cdot r)\cdot dk f(k) vanishes outside the boundaries k=0 and k=2; I have got k and f(k) as float arrays, so we...
4. ### Localization vs De Broglie wavelenght

Localization vs De Broglie wavelength First of all, I would like to say hello to everybody since this is my first post, even if it's been some time since I read Physics Forums. Second, sorry for my bad English, I'm Italian :) Third, the issue: I read from my teacher's notes, that a...