## Contents

## USAGE:

distance = gsw_distance(long,lat,{p})

## DESCRIPTION:

Calculates the distance in metres between successive points in the
vectors long and lat, computed using the Haversine formula on a
spherical earth of radius 6,371 km, being the radius of a sphere having
the same volume as Earth. For a sperical Earth of radius 6,371,000 m,
one nautical mile is 1,853.2488 m, thus one degree of latitude is
111,194.93 m.
Note. Distances are probably good to better than 1% of the "true"
distance on the ellipsoidal earth.

## INPUT:

long = longitude in decimal degress [ 0 ... +360 ]
or [ -180 ... +180 ]
lat = latitude in decimal degress north [ -90 ... +90 ]

OPTIONAL:

p = sea pressure ( default is 0 ) [ dbar ]
( i.e. absolute pressure - 10.1325 dbar )

lat and long need to have the same dimensions, Mx1 or 1xN or MxN.
p, if provided, may have dimensions 1x1 or Mx1 or 1xN or MxN,
where lat & long are Mx1 or 1xN or MxN.

## OUTPUT:

distance = Distance between points on a spherical [ m ]
Earth at pressure (p)
Note. The output is in m not km.

## EXAMPLE:

Example 1 Station 1 is at (-35, 159) & Station 2 is at (35, 220)
long = [159 220]
lat = [-35 35]

distance = gsw_distance(long,lat)

distance =

1.003097465291600e+007

Example 2 Station 1 is at (-35, 159) & Station 2 is at (35, 220),
the pressure at Station 1 is 200 and at Station 2 it is 1000 dbar.
long = [159 220]
lat = [-35 35]
p = [200 1000]

Note that the pressures are not equal, we therefore calculate the
distance between stations at the mid pressure.

distance = gsw_distance(long,lat,p)

distance =

1.003003651722478e+007

Example 3 If the locations are entered as pairs in a column it will
calculate the distances between each pairs of stations (points).
long = [159 220; 140 200]
lat = [-35 35; 20 45]
p = [200 1000]

distance = gsw_distance(long,lat,p)

distance =

1.003003651722478e+007
0.611126188161320e+006

## AUTHOR:

6th November, 2000 by Rich Pawlowicz [ help@teos-10.org ]
Note. This function was extracted from Rich Pawlowicz's m_map package,
which is available from http://www.eos.ubc.ca/~rich/map.html

MODIFIED:
15th June, 2020 by Paul Barker and Trevor McDougall.

## VERSION NUMBER:

3.06.12 (15th June, 2020)

## REFERENCE:

Rich Pawlowicz's m_map package. http://www.eos.ubc.ca/~rich/map.html

The software is available from http://www.TEOS-10.org