Euler's relations & 'Epicycloids'

  • Context: Graduate 
  • Thread starter Thread starter saviourmachine
  • Start date Start date
  • Tags Tags
    Relations
Click For Summary

Discussion Overview

The discussion revolves around the concept of epicycloids and their relation to Euler's relations, exploring their visualization and connections to amplitude modulation and complex Fourier series. The scope includes theoretical exploration and mathematical reasoning.

Discussion Character

  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • One participant describes an epicycloid as a superimposed circle on another circle and proposes a method to visualize this by moving the second circle's center, suggesting that this approach leads to insights about negative frequency.
  • Another participant connects the movement of points on the circles to amplitude modulation, proposing that the first circle's frequency acts as a carrier frequency while the second circle's frequency modulates it, hinting at a potential Java applet for visualization.
  • A different participant suggests that complex Fourier series can also be visualized as superimposed circles with varying frequencies, raising a question about the visualization technique.
  • One participant requests a moderator to move the thread if it is deemed inappropriate for the forum, indicating uncertainty about the thread's relevance.

Areas of Agreement / Disagreement

Participants express various ideas and connections regarding epicycloids, amplitude modulation, and Fourier series, but there is no consensus on the appropriateness of the thread or the visualization techniques discussed.

Contextual Notes

Participants mention the need for clarification on Euler's relations and visualization methods, but the discussion does not resolve these aspects or provide definitive answers.

saviourmachine
Messages
96
Reaction score
0
The idea
An epicycloid is a superimposed circle on another circle. http://www.math.dartmouth.edu/~dlittle/java/SpiroGraph/ can you find a java applet to show you. These epicycloids are tied to each other at their circumferences. But, what does change when using a slightly easier method, and superimpose the second circle (the referent) using it's centre!?

A point on the first circle moves along its circumference, and because it is the centre of the second circle, the whole second circle does move with along it. Now comes the clue: do the same with the second circle. Take a point at the circumference of the second circle and move in the opposite direction (with a negative frequency). Like you can see will this point move along the horizontal axis. Not much have to be imagined to realize that this traject will be equal to [tex]2 \cos{\omega}[/tex]. Of course is this equals the sum of [tex]\exp{j \omega t}[/tex] and [tex]\exp{-j \omega t}[/tex], but it's cool that with rotating in the other direction a meaning is assigned to the concept "negative frequency".

http://www.annevanrossum.nl/pictures/science/Epicycloid.gif

Does anyone know of a clarification of Euler's relations using these drawing techniques?

___
Edit: Changed math to Latex.

__
Observation: Odd, that the image can't be displayed. That's for paying members?
 
Last edited by a moderator:
Physics news on Phys.org
Amplitude modulation

Amplitude modulation
Now I'm thinking about it. The frequency [tex]f_1[/tex] of the point on the first circle can be the carrier frequency in AM modulation. The frequency [tex]f_2[/tex] of the point of the second circle can be a frequency that modulates the carrier. Projecting the second point on the horizontal x gives the resulting AM signal. If I had time I'd like to make a java applet to show that. The complex envelope is approximated a circle (radius equals sum of radius of circle 1 and 2)! [tex]g(t)=A_c \exp{j \theta(t)}[/tex]
 
Last edited:
Complex Fourier series

Another thought. Even the complex Fourier series can be visualized as superimposed circles with different frequencies isn't it?
[tex]f(t)=\sum_{n=-\infty}^{n=\infty}{A_n \exp{jn\omega_0t}}[/tex] with [tex]A_n[/tex] the radius of the circle n.

Does nobody know of this manner of visualization?
 
Can a moderator move this thread if it's not appropriate here? It's not homework...
 

Similar threads

  • · Replies 25 ·
Replies
25
Views
3K
  • · Replies 32 ·
2
Replies
32
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 40 ·
2
Replies
40
Views
6K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 20 ·
Replies
20
Views
4K
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K