Ann: Simple Spirograph-like toy program.

[Dennis Brown]

On Jun 18, 2005, at 2:40 PM, Alex Tweedly wrote:

> Dennis Brown wrote:
>
>
>> Alex,
>>
>> Thanks for sharing this stack.  I remember when I was a teenager   
>> (about 3,000 years ago), I helped my dad build a king size dual   
>> pendulum "spirograph".  One pendulum ran the x axis and the other  
>> ran  the y axis.  It produced very interesting patterns because  
>> each  pendulum was running a sine wave that would decay in  
>> amplitude with  time.  It might be interesting to add that idea  
>> somehow to your stack.
>>
>
> Uh, Dennis - I think that would require understanding the maths, as  
> opposed to merely translating it, which is all I have done so far :-)
>
> So was it just two independent pendulums (pendula?), each  
> controlling an axis independently ? Should be worth a try ... do I  
> need to allow for Coriolis force :-) ?
> Follow up to come - but not too soon.

Alex,

The math should just be a slider for frequency control of a sine  
function multiplied by an initial amplitude value that is reduced  
logarithmically with time based on a slider of friction value.  You  
need one for each axis x,y.  It should be fun figuring out the math,  
since you can see the results of what you are trying.  As for the  
Coriolis force... a slider for latitude perhaps 8^)

Dennis