faa.tg.units
Class MagneticVariation

java.lang.Object
  faa.tg.units.AMeasure
      faa.tg.units.Angle
          faa.tg.units.MagneticVariation

All Implemented Interfaces:

HasText, java.io.Serializable, java.lang.Cloneable, java.lang.Comparable<AMeasure>

public class MagneticVariation
extends Angle

(It seems that this is defined to be the same as MagneticDeclination, which is the preferred usage: use MagneticDeclination instead, unless there is a reason to use this.) MagneticVariation represents the angular measure of the Earth's magnetic Field with respect to true North. Clockwise offsets are positive. Generally seen as 10W (-10.0 degrees) or 12E (+12.0 degrees).

MagneticVariation and MagneticDeclination will be considered the same in the simulation (execpt possibly for a sign problem).

What is the Earth's magnetic field? The Earth acts like a great spherical magnet, in that it is surrounded by a magnetic field. The Earth's magnetic field resembles, in general, the field generated by a dipole magnet (i.e., a straight magnet with a north and south pole) located at the center of the Earth. The axis of the dipole is offset from the axis of the Earth's rotation by approximately 11 degrees. This means that the north and south geographic poles and the north and south magnetic poles are not located in the same place. At any point, the Earth's magnetic field is characterized by a direction and intensity which can be measured. Often the parameters measured are the magnetic declination, D, the horizontal intensity, H, and the vertical intensity, Z. From these these elements, all other parameters of the magnetic field can be calculated.

What are the magnetic elements? To measure the Earth's magnetism in any place, we must measure the direction and intensity of the field. The parameters describing the direction of the magnetic field are declination (D), inclination (I). D and I are measured in units of degrees. The intensity of the total field (F) is described by the horizontal component (H), vertical component (Z), and the north (X) and east (Y) components of the horizontal intensity. These components may be measured in units of Oersted (1 oersted=1gauss) but are generally reported in nanoTesla (1nT * 100,000 = 1 0ersted). The Earth's magnetic field intensity is roughly between 25,000 - 65,000 nT (.25 - .65 oersted). Magnetic declination is the angle between magnetic north and true north. D is considered positive when the angle measured is east of true north and negative when west. Magnetic inclination is the angle between the horizontal plane and the total field vector. In older liturature, the term 'magnetic elements' often refered to D, I, and H.

See the source:MagneticVariation.java

Version:

$Id: MagneticVariation.java,v 3.2 2008/08/07 19:59:03 lykensj Exp $

Author:

Michael E Ross

See Also:

MagneticDeclination, AUnits, AMeasure, MagneticHeading, Units.radians, Serialized Form

Field Summary

static java.lang.String	CVS_VERSION_ID The CVS Version ID
(package private) static long	serialVersionUID
static MagneticVariation	ZERO

Fields inherited from class faa.tg.units.Angle

D180_DIV_PI, DEG_1, DEG_180, DEG_270, DEG_30, DEG_330, DEG_5, DEG_60, DEG_90, DEG_NEG180, DEG_NEG270, DEG_NEG30, DEG_NEG5, DEG_NEG90, DEG_PER_RAD, NEG_NINETY_DEG, NEG_ONEEIGHTY_DEG, NINETY_DEG, ONEEIGHTY_DEG, PI, PI_DIV_180, PI_DIV_2, PI_DIV_4, PI_MUL_2, PI_MUL_4, RAD_PER_DEG, THIRTY_DEG, THREETHIRTY_DEG, TWOSEVENTY_DEG

Fields inherited from class faa.tg.units.AMeasure

DEC0, DEC0_, DEC00, DEC000, DEC1, DEC1_, DEC12, DEC12_, DEC1L, DEC1L_, DEC2, DEC2_, DEC3, DEC3_, DEC4, DEC4_, DEC5, DEC5_, DEC6, DEC6_, DEC7, DEC7_, DEC9, DEC9_, itsValue, TIME_FRACTION

Constructor Summary

MagneticVariation(double theValue, AngleUnits theUnits)
Constructor for the MagneticVariation class.

MagneticVariation(java.lang.String degreeOffset)
Constructor for the MagneticVariation class.

Method Summary

boolean	eq(MagneticVariation theMeasure) This method provides a test for equality.
boolean	ge(MagneticVariation theMeasure) This method provides a test for greater than / equal to.
boolean	gt(MagneticVariation theMeasure) This method provides a test for greater than.
boolean	le(MagneticVariation theMeasure) This method provides a test for less than / equal to.
boolean	lt(MagneticVariation theMeasure) This method provides a test for less than.
static void	main(java.lang.String[] args)
double	ratio(MagneticVariation val) This division method produces a dimensionless ratio of like measures.
java.lang.String	toString() Returns the String representation of this object in the units used to create it.

Methods inherited from class faa.tg.units.Angle

abs, add, aeq, as, average, cos, diff, eq, ge, gt, isBetween, le, lt, parseDmsString, ratio, reciprocalAngle, removeDelimiters, sin, sub, tan, toDmsString, toRadialString, toText

Methods inherited from class faa.tg.units.AMeasure

absoluteValue, add, as, as, clone, compareTo, debug, div, eq, equals, ge, getAUnit, getCanonicalUnit, getCanonicalValue, getInitialUnit, getUnitClass, gt, hashCode, isBetween, le, lt, mul, ratio, sub, toAMeasure, toString, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

serialVersionUID

static final long serialVersionUID

See Also:

Constant Field Values

CVS_VERSION_ID

public static final java.lang.String CVS_VERSION_ID

The CVS Version ID

See Also:

Constant Field Values

ZERO

public static final MagneticVariation ZERO

Constructor Detail

MagneticVariation

public MagneticVariation(double theValue,
                         AngleUnits theUnits)

Constructor for the MagneticVariation class.

Parameters:

theValue - the magnitude of MagneticVariation as a double

theUnits - the units of the value that will be stored (ex: radians)

MagneticVariation

public MagneticVariation(java.lang.String degreeOffset)
                  throws java.lang.NumberFormatException

Constructor for the MagneticVariation class.

Parameters:

degreeOffset - the number of degrees E or W of True North

Throws:

java.lang.NumberFormatException

Method Detail

ratio

public double ratio(MagneticVariation val)

This division method produces a dimensionless ratio of like measures.

Returns:

the ratio of the two measures

eq

public boolean eq(MagneticVariation theMeasure)

This method provides a test for equality. It overrides the method in the superclass and checks for like AMeasures as well as doing the cast for you.

Returns:

Returns boolean indicating whether values are equal.

lt

public boolean lt(MagneticVariation theMeasure)

This method provides a test for less than. It overrides the method in the superclass and checks for like AMeasures as well as doing the cast for you.

Returns:

Returns whether this value is less than the given value.

gt

public boolean gt(MagneticVariation theMeasure)

This method provides a test for greater than. It overrides the method in the superclass and checks for like AMeasures as well as doing the cast for you.

Returns:

Returns whether this value is greater than the given value.

ge

public boolean ge(MagneticVariation theMeasure)

This method provides a test for greater than / equal to. It overrides the method in the superclass and checks for like AMeasures as well as doing the cast for you.

Returns:

Returns result of test for greater than or equal to.

le

public boolean le(MagneticVariation theMeasure)

This method provides a test for less than / equal to. It overrides the method in the superclass and checks for like AMeasures as well as doing the cast for you.

Returns:

Returns result of test for less than or equal to.

toString

public java.lang.String toString()

Returns the String representation of this object in the units used to create it.

Overrides:

toString in class Angle

Returns:

A String representing the measure in the canonical unit.

See Also:

Units

main

public static void main(java.lang.String[] args)