Significant digits in a float?

[Chris Angelico]

On Wed, Apr 30, 2014 at 12:31 PM, Ethan Furman <ethan at stoneleaf.us> wrote:
> On 04/29/2014 03:51 PM, Chris Angelico wrote:
>> Any point where the mile east takes you an exact number of times
>> around the globe. So, anywhere exactly one mile north of that, which
>> is a number of circles not far from the south pole.
>
> Perhaps my geography is rusty, but I was under the impression that one
> cannot travel south if one is at the South Pole (axial, not magnetic).

Correct, but there's a place not far from the South Pole where the
circumference of the earth (travelling east) will be exactly one mile.
I could calculate where that would be on a perfect sphere, but earth
isn't, so I'll just say "near the South Pole". If you start exactly
one mile north of that circle, then you can accomplish the original
challenge. Also, if your mile east takes you exactly twice around the
circumference, you still achieve the same thing, so there's another
circle (one mile north of *that* circle), and another at the
three-times-around circle, etc.

But I think a better answer is New York City. You start out lost, you
go a mile south, a mile east, a mile north, and you are again lost.

ChrisA