Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
NCTM or The Math Forum.



Re: Like moths to a flame
Posted:
Jun 17, 1996 4:08 AM


Quentin Grady (quentin@inhb.co.nz) 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.



