On Thu, 2005-02-03 at 18:31 -0700, Michael Fuhr wrote:
> Do you have a reason to favor DMS over DDD.DDDD? The latter is
> easy to use in arithmetic expressions, such as formulae for calculating
> the distance between two points (haversine, law of cosines, etc.).
>
You are entirely correct mathematically. I do prefer DMS, however, based
on human factors:
1. I am the only one who will input data, and likely for fewer than
40-50 records in total. Some inconvenience in data input is OK.
2. DMS is how my handheld GPS presents data, and is easier for me to
remember and find intuitively on a chart when actually looking for an
airport.
3. There will be little or no need for formulaic manipulation. I have
less interest in direct or great-circle distances than I do in actual
distance *flown*, and I intend to input the actual routes and distances
(again, as measured by charts and/or GPS).
I'll do some research on the 8.0 composite types, although I'll be stuck
on 7.x for a while yet. I'll also check out the contrib/earthdistance
module... thanks for your comments on both. This is the kind of thing I
was hoping to learn from this discussion.
On a more trivial note, I find myself now wondering what linear distance
over land is actually represented by one arc-second of latitude or
longitude... will have to figure out the math involved. :-)
Cheers,
--
Rodolfo J. Paiz <rpaiz@simpaticus.com>