# If this is not a Bernoulli spiral, what is it then?

1. Dec 25, 2011

### Signa

I met this old nerd wearing a tie with a certain spiral, which does not look like a Bernoulli spiral to me. He actually told me, what it was, but I seem to have lost the note and time made me forget it. I wouldn´t be able to describe properly, so I have a photograph of the tie on my flickr:
http://flic.kr/p/b1Dt6P

Anyone happens to know, what it is?

Much obliged,
Arthur

2. Dec 25, 2011

### Danger

Welcome to PF, Arthur. I'm afraid that I can't help you out on this.
It's a damned cool design, though. If it turns out to mean something that I like, I wouldn't mind getting it as a tatoo.

3. Dec 25, 2011

4. Dec 25, 2011

### Danger

Perhaps... I guess that rules out the tatoo; it looks too much like a nautilus, and I'm allergic to shellfish.

5. Dec 25, 2011

### Bobbywhy

6. Dec 26, 2011

### Signa

Thanks for the comments! I just don´t really think it´s the Golden or Equiangular Spiral as the angle to the rightmost slope to the x-axis seems a bit too steep for it to truly match.
Sure, it´s an embroidery and geometric accuracy cannot be fully expected, but I remember the guy telling another story and one could embroider the equiangular spiral much more clear!
So I´m still thankful for more suggestions.
By the way, here is the guy, who came with it:
http://flic.kr/p/b1DsCc
This guy makes it look even cooler on a tie, than as a tattoo...

7. Dec 26, 2011

### rcgldr

Looks like spiral of Archimedes, in polar coordinates:

r = a θ , θ starting at 0

but the logo appears rotated left 90°, which would be:

r = a (θ - π/2), θ starting at π/2

For the rotated image, imagine rotating the image from the wiki article 90° to the left (tilt your head 90° to the right) and note the first 360° of the spiral would look like the logo. Link to the wiki artilcle.

http://en.wikipedia.org/wiki/Archimedean_spiral

Last edited: Dec 26, 2011
8. Dec 26, 2011

### Signa

It really does look more like the archimedean spiral, than any other. In all drawings I found, the archimedean spiral starts at the pole, while the equiangular spiral never reaches the pole. In the logo on the tie, the spiral quite clearly starts at 0.
Thanks a lot rcgldr and the other for help!

Happy New Year!