Calculating distance from Lat/Long
 

Hi,

I'm writing a program for Linux that displays position (from GPS) on a
scanned-in chart, and would like it to calculate distance from current
position to the cursor.

How do you calculate distance between two points using lat/long? If
they're due North/South, I can do it ( 1 minute of lat = 1 NM) but how do
you calculate distance from longitude? Perhaps some formula based on the
circumfrence of the Earth at the equator and the latitude?

Lloyd Sumpter

Calculating distance from Lat/Long
 

If you have a Bowditch, look under "Sailings" or look in Bowditch online
for the same info.
What you need will be in there.

otn

Lloyd Sumpter wrote:
Hi,

I'm writing a program for Linux that displays position (from GPS) on a
scanned-in chart, and would like it to calculate distance from current
position to the cursor.

How do you calculate distance between two points using lat/long? If
they're due North/South, I can do it ( 1 minute of lat = 1 NM) but how do
you calculate distance from longitude? Perhaps some formula based on the
circumfrence of the Earth at the equator and the latitude?

Lloyd Sumpter

Calculating distance from Lat/Long
 

If you have a Bowditch, look under "Sailings" or look in Bowditch online
for the same info.
What you need will be in there.

otn

Lloyd Sumpter wrote:
Hi,

I'm writing a program for Linux that displays position (from GPS) on a
scanned-in chart, and would like it to calculate distance from current
position to the cursor.

How do you calculate distance between two points using lat/long? If
they're due North/South, I can do it ( 1 minute of lat = 1 NM) but how do
you calculate distance from longitude? Perhaps some formula based on the
circumfrence of the Earth at the equator and the latitude?

Lloyd Sumpter

Calculating distance from Lat/Long
 

You want http://williams.best.vwh.net/avform.htm

"Lloyd Sumpter" wrote in message
...
Hi,

I'm writing a program for Linux that displays position (from GPS) on a
scanned-in chart, and would like it to calculate distance from current
position to the cursor.

How do you calculate distance between two points using lat/long? If
they're due North/South, I can do it ( 1 minute of lat = 1 NM) but how do
you calculate distance from longitude? Perhaps some formula based on the
circumfrence of the Earth at the equator and the latitude?

Lloyd Sumpter

Calculating distance from Lat/Long
 

You want http://williams.best.vwh.net/avform.htm

"Lloyd Sumpter" wrote in message
...
Hi,

I'm writing a program for Linux that displays position (from GPS) on a
scanned-in chart, and would like it to calculate distance from current
position to the cursor.

How do you calculate distance between two points using lat/long? If
they're due North/South, I can do it ( 1 minute of lat = 1 NM) but how do
you calculate distance from longitude? Perhaps some formula based on the
circumfrence of the Earth at the equator and the latitude?

Lloyd Sumpter

Calculating distance from Lat/Long
 

That will do it - thanks! Curious about how those formulae were developed,
though...

Lloyd


On Thu, 04 Dec 2003 14:46:15 +0000, SpamJam wrote:

You want http://williams.best.vwh.net/avform.htm

"Lloyd Sumpter" wrote in message
...
Hi,

I'm writing a program for Linux that displays position (from GPS) on a
scanned-in chart, and would like it to calculate distance from current
position to the cursor.

How do you calculate distance between two points using lat/long? If
they're due North/South, I can do it ( 1 minute of lat = 1 NM) but how do
you calculate distance from longitude? Perhaps some formula based on the
circumfrence of the Earth at the equator and the latitude?

Lloyd Sumpter

Calculating distance from Lat/Long
 

That will do it - thanks! Curious about how those formulae were developed,
though...

Lloyd


On Thu, 04 Dec 2003 14:46:15 +0000, SpamJam wrote:

You want http://williams.best.vwh.net/avform.htm

"Lloyd Sumpter" wrote in message
...
Hi,

I'm writing a program for Linux that displays position (from GPS) on a
scanned-in chart, and would like it to calculate distance from current
position to the cursor.

How do you calculate distance between two points using lat/long? If
they're due North/South, I can do it ( 1 minute of lat = 1 NM) but how do
you calculate distance from longitude? Perhaps some formula based on the
circumfrence of the Earth at the equator and the latitude?

Lloyd Sumpter

Calculating distance from Lat/Long
 

Lloyd Sumpter wrote:

That will do it - thanks! Curious about how those formulae were developed,
though...

Spherical Trigonometry - not for the fain of heart.
--
Dan Best - (707) 431-1662, Healdsburg, CA 95448
B-2/75 1977-1979
Tayana 37 #192, "Tricia Jean"
http://rangerbest.home.comcast.net/TriciaJean.JPG

Calculating distance from Lat/Long
 

Lloyd Sumpter wrote:

That will do it - thanks! Curious about how those formulae were developed,
though...

Spherical Trigonometry - not for the fain of heart.
--
Dan Best - (707) 431-1662, Healdsburg, CA 95448
B-2/75 1977-1979
Tayana 37 #192, "Tricia Jean"
http://rangerbest.home.comcast.net/TriciaJean.JPG

Calculating distance from Lat/Long
 

"Lloyd Sumpter" wrote in message
...

That will do it - thanks! Curious about how those formulae were developed,
though...


I once tried to imagine Bowditch working and refining his tables and
formulas manually. Must have been total dedication.

Steve
s/v Good Intentions
Lloyd


On Thu, 04 Dec 2003 14:46:15 +0000, SpamJam wrote:

You want http://williams.best.vwh.net/avform.htm

"Lloyd Sumpter" wrote in message
...
Hi,

I'm writing a program for Linux that displays position (from GPS) on
a
scanned-in chart, and would like it to calculate distance from current
position to the cursor.

How do you calculate distance between two points using lat/long? If
they're due North/South, I can do it ( 1 minute of lat = 1 NM) but how
do
you calculate distance from longitude? Perhaps some formula based on
the
circumfrence of the Earth at the equator and the latitude?

Lloyd Sumpter