hirondelle.formula.function.builtin
Class Distance

Object
  hirondelle.formula.function.builtin.Distance

All Implemented Interfaces:

Function

public final class Distance
extends Object
implements Function

distance(φ1, λ1, φ2, λ2): the distance in kilometres from one place to another.

Constructor Summary

Distance()

Method Summary

Decimal

calculate(Decimal... aArgs) Returns the distance between two points on the Earth's surface, in kilometers.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Distance

public Distance()

Method Detail

calculate

public Decimal calculate(Decimal... aArgs)

Returns the distance between two points on the Earth's surface, in kilometers.

This method takes 4 parameters, in the following order:

• φ1 - the latitude of point 1, in degrees
• λ1 - the longitude of point 1, in degrees
• φ2 - the latitude of point 2, in degrees
• λ2 - the longitude point 2, in degrees

Latitude is positive north of the equator, and negative south of the equator. Longitude is positive to the east of Greenwich meridian (Asia, for example), and negative to the west of the Greenwich meridian (America, for example).

The return value usually has a large number of decimal places. That precision is spurious and without physical significance, since the underlying implementation makes the approximation that the Earth is spherical.

The caller should round the result to a reasonable number of decimal places.

This implementation uses two underlying formulas - one appropriate for large distances, and one appropriate for small distances.

Specified by:

calculate in interface Function

Parameters:

aArgs - 0 or more arguments to the function.