Fast geodesic calculations (series approximation)

These functions provide the same geodesic calculations as geodesic_direct(), geodesic_inverse(), etc., but use a series approximation that is slightly faster at the cost of reduced precision (accurate to ~15 nanometers vs full double precision for the exact versions).

For most applications, the difference is negligible and these faster versions are recommended.

geodesic_direct_fast(x, azi, s)

geodesic_inverse_fast(x, y)

geodesic_path_fast(x, y, n = 100L)

geodesic_distance_fast(x, y)

geodesic_distance_matrix_fast(x, y = NULL)

Arguments

x

A two-column matrix or data frame of starting coordinates (longitude, latitude) in decimal degrees.

azi

Numeric vector of azimuths (bearings) in degrees, measured clockwise from north.

s

Numeric vector of distances in meters.

y

A two-column matrix or data frame of ending coordinates (longitude, latitude) in decimal degrees.

n

Integer number of points to generate along the path (including start and end points).

Value

Same as the corresponding exact geodesic functions.

See also

geodesic_direct(), geodesic_inverse() for exact versions

Examples

# Fast inverse: London to New York
geodesic_inverse_fast(c(-0.1, 51.5), c(-74, 40.7))
#>   lon1 lat1 lon2 lat2     s12      azi1      azi2     m12       M12       M21
#> 1 -0.1 51.5  -74 40.7 5587820 -71.62462 -128.7635 4900877 0.6407216 0.6404073
#>             S12
#> 1 -4.040644e+13

# Compare to exact version
geodesic_inverse(c(-0.1, 51.5), c(-74, 40.7))$s12
#> [1] 5587820
geodesic_inverse_fast(c(-0.1, 51.5), c(-74, 40.7))$s12
#> [1] 5587820