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Topic: Like moths to a flame
Replies: 1   Last Post: Jun 17, 1996 4:08 AM

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Tim Poston

Posts: 44
Registered: 12/3/04
Re: Like moths to a flame
Posted: Jun 17, 1996 4:08 AM
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Quentin Grady ( wrote:
: G'day G'day folks,

: In one of his books, Stephen Gould mentions the path of a moth to a flame as
: a logarithmic spiral. He states that this logarithmic spiral is the *only* curve that
: doen't change its shape as it is enlarged. I presume he dismisses straight lines.

: If you have any ideas on what sort of logarithmic spiral this is, please email me.

No, he _includes_ straight lines.
You can write a logarithmic spiral most succinctly in polar coordinates,

theta = A s
r = exp(s)

where s parametrizes the curve and A is a constant.
Set that constant to 0 and you get a straight line.

A straight line is a special case of all kinds of things...

Tim Poston Institute of Systems Science, National University of Singapore
A billion dollars here, a billion dollars there,
and pretty soon you're talking Orbital Yen.

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