java.lang.Object
- org.orekit.utils.units.Unit

All Implemented Interfaces:

Serializable
```
public class Unit
extends Object
implements Serializable
```
Basic handling of multiplicative units.
This class is by no means a complete handling of units. For complete support, look at libraries like UOM. This class handles only time, length, mass and current dimensions, as well as angles (which are dimensionless).

Instances of this class are immutable.

Since:

11.0

Author:

Luc Maisonobe

See Also:

UOM, Serialized Form

Field Summary

Fields
Modifier and Type	Field	Description
`static Unit`	`AMPERE`	Ampere unit.
`static Unit`	`ARC_MINUTE`	Arc minute unit.
`static Unit`	`ARC_SECOND`	Arc second unit.
`static Unit`	`BAR`	Bar unit.
`static Unit`	`COULOMB`	Coulomb unit.
`static Unit`	`DAY`	Day unit.
`static Unit`	`DEGREE`	Degree unit.
`static Unit`	`EARTH_RADII`	Earth Radii used as Bstar unit in CCSDS OMM.
`static Unit`	`GRAM`	Gram unit.
`static Unit`	`HERTZ`	Hertz unit.
`static Unit`	`HOUR`	Hour unit.
`static Unit`	`JOULE`	Joule unit.
`static Unit`	`KILOGRAM`	Kilogram unit.
`static Unit`	`KILOMETRE`	Kilometre unit.
`static Unit`	`METRE`	Metre unit.
`static Unit`	`MINUTE`	Minute unit.
`static Unit`	`NEWTON`	Newton unit.
`static Unit`	`NONE`	No unit.
`static Unit`	`OHM`	Ohm unit.
`static Unit`	`ONE`	Dimensionless unit.
`static Unit`	`PASCAL`	Pascal unit.
`static Unit`	`PERCENT`	Percentage unit.
`static Unit`	`RADIAN`	Radian unit.
`static Unit`	`REVOLUTION`	Revolution unit.
`static Unit`	`SECOND`	Second unit.
`static Unit`	`SOLAR_FLUX_UNIT`	Solar Flux Unit.
`static Unit`	`TESLA`	tesla unit.
`static Unit`	`TOTAL_ELECTRON_CONTENT_UNIT`	Total Electron Content Unit.
`static Unit`	`VOLT`	Volt unit.
`static Unit`	`WATT`	Watt unit.
`static Unit`	`YEAR`	Julian year unit.

Constructor Summary

Constructors
Constructor	Description
`Unit(String name, double scale, Fraction mass, Fraction length, Fraction time, Fraction current, Fraction angle)`	Simple constructor.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Unit`	`alias(String newName)`	Create an alias for a unit.
`Unit`	`divide(String newName, Unit other)`	Create quotient of units.
`static void`	`ensureCompatible(String description, List<Unit> reference, boolean allowScaleDifferences, List<Unit> units)`	Ensure some units are compatible with reference units.
`boolean`	`equals(Object unit)`	Check if the instance represents the same unit as another instance.
`double`	`fromSI(double value)`	Convert a value from SI units.
`double`	`fromSI(Double value)`	Convert a value from SI units.
`Fraction`	`getAngle()`	Get the angle exponent.
`Fraction`	`getCurrent()`	Get the current exponent.
`Fraction`	`getLength()`	Get the length exponent.
`Fraction`	`getMass()`	Get the mass exponent.
`String`	`getName()`	Get the name of the unit.
`double`	`getScale()`	Get the scaling factor to SI units.
`Fraction`	`getTime()`	Get the time exponent.
`int`	`hashCode()`	Get a hashcode for this unit.
`Unit`	`multiply(String newName, Unit other)`	Create product of units.
`static Unit`	`parse(String unitSpecification)`	Parse a unit.
`Unit`	`power(String newName, Fraction exponent)`	Create power of unit.
`boolean`	`sameDimension(Unit other)`	Check if a unit has the same dimension as another unit.
`Unit`	`sameDimensionSI()`	Create the SI unit with same dimension.
`Unit`	`scale(String newName, double factor)`	Scale a unit.
`Unit`	`sqrt(String newName)`	Create root of unit.
`double`	`toSI(double value)`	Convert a value to SI units.
`double`	`toSI(Double value)`	Convert a value to SI units.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - NONE
```
public static final Unit NONE
```
    No unit.
  - ONE
```
public static final Unit ONE
```
    Dimensionless unit.
  - PERCENT
```
public static final Unit PERCENT
```
    Percentage unit.
  - SECOND
```
public static final Unit SECOND
```
    Second unit.
  - MINUTE
```
public static final Unit MINUTE
```
    Minute unit.
  - HOUR
```
public static final Unit HOUR
```
    Hour unit.
  - DAY
```
public static final Unit DAY
```
    Day unit.
  - YEAR
```
public static final Unit YEAR
```
    Julian year unit.
    
    See Also:
    
    SI Units at IAU
  - HERTZ
```
public static final Unit HERTZ
```
    Hertz unit.
  - METRE
```
public static final Unit METRE
```
    Metre unit.
  - KILOMETRE
```
public static final Unit KILOMETRE
```
    Kilometre unit.
  - KILOGRAM
```
public static final Unit KILOGRAM
```
    Kilogram unit.
  - GRAM
```
public static final Unit GRAM
```
    Gram unit.
  - AMPERE
```
public static final Unit AMPERE
```
    Ampere unit.
  - RADIAN
```
public static final Unit RADIAN
```
    Radian unit.
  - DEGREE
```
public static final Unit DEGREE
```
    Degree unit.
  - ARC_MINUTE
```
public static final Unit ARC_MINUTE
```
    Arc minute unit.
  - ARC_SECOND
```
public static final Unit ARC_SECOND
```
    Arc second unit.
  - REVOLUTION
```
public static final Unit REVOLUTION
```
    Revolution unit.
  - NEWTON
```
public static final Unit NEWTON
```
    Newton unit.
  - PASCAL
```
public static final Unit PASCAL
```
    Pascal unit.
  - BAR
```
public static final Unit BAR
```
    Bar unit.
  - JOULE
```
public static final Unit JOULE
```
    Joule unit.
  - WATT
```
public static final Unit WATT
```
    Watt unit.
  - COULOMB
```
public static final Unit COULOMB
```
    Coulomb unit.
  - VOLT
```
public static final Unit VOLT
```
    Volt unit.
  - OHM
```
public static final Unit OHM
```
    Ohm unit.
  - TESLA
```
public static final Unit TESLA
```
    tesla unit.
  - SOLAR_FLUX_UNIT
```
public static final Unit SOLAR_FLUX_UNIT
```
    Solar Flux Unit.
  - TOTAL_ELECTRON_CONTENT_UNIT
```
public static final Unit TOTAL_ELECTRON_CONTENT_UNIT
```
    Total Electron Content Unit.
  - EARTH_RADII
```
public static final Unit EARTH_RADII
```
    Earth Radii used as Bstar unit in CCSDS OMM.
- Constructor Detail
  - Unit
```
public Unit(String name,
            double scale,
            Fraction mass,
            Fraction length,
            Fraction time,
            Fraction current,
            Fraction angle)
```
    Simple constructor.
    
    Parameters:
    
    name - name of the unit
    
    scale - scaling factor to SI units
    
    mass - mass exponent
    
    length - length exponent
    
    time - time exponent
    
    current - current exponent
    
    angle - angle exponent
- Method Detail
  - getName
```
public String getName()
```
    Get the name of the unit.
    
    Returns:
    
    name of the unit
  - getScale
```
public double getScale()
```
    Get the scaling factor to SI units.
    
    Returns:
    
    scaling factor to SI units
  - getMass
```
public Fraction getMass()
```
    Get the mass exponent.
    
    Returns:
    
    mass exponent
  - getLength
```
public Fraction getLength()
```
    Get the length exponent.
    
    Returns:
    
    length exponent
  - getTime
```
public Fraction getTime()
```
    Get the time exponent.
    
    Returns:
    
    time exponent
  - getCurrent
```
public Fraction getCurrent()
```
    Get the current exponent.
    
    Returns:
    
    current exponent
  - getAngle
```
public Fraction getAngle()
```
    Get the angle exponent.
    
    Returns:
    
    angle exponent
  - sameDimension
```
public boolean sameDimension(Unit other)
```
    Check if a unit has the same dimension as another unit.
    
    Parameters:
    
    other - other unit to check against
    
    Returns:
    
    true if unit has the same dimension as the other unit
  - sameDimensionSI
```
public Unit sameDimensionSI()
```
    Create the SI unit with same dimension.
    
    Returns:
    
    a new unit, with same dimension as instance and scaling factor set to 1.0
  - ensureCompatible
```
public static void ensureCompatible(String description,
                                    List<Unit> reference,
                                    boolean allowScaleDifferences,
                                    List<Unit> units)
```
    Ensure some units are compatible with reference units.
    
    Parameters:
    
    description - description of the units list (for error message generation)
    
    reference - reference units
    
    units - units to check
    
    allowScaleDifferences - if true, unit with same dimension but different scale (like KILOMETRE versus METRE) are allowed, otherwise they will trigger an exception
    
    Throws:
    
    OrekitException - if units are not compatible (number of elements, dimensions or scaling)
  - alias
```
public Unit alias(String newName)
```
    Create an alias for a unit.
    
    Parameters:
    
    newName - name of the new unit
    
    Returns:
    
    a new unit representing same unit as the instance but with a different name
  - scale
```
public Unit scale(String newName,
                  double factor)
```
    Scale a unit.
    
    Parameters:
    
    newName - name of the new unit
    
    factor - scaling factor
    
    Returns:
    
    a new unit representing scale times the instance
  - power
```
public Unit power(String newName,
                  Fraction exponent)
```
    Create power of unit.
    
    Parameters:
    
    newName - name of the new unit
    
    exponent - exponent to apply
    
    Returns:
    
    a new unit representing the power of the instance
  - sqrt
```
public Unit sqrt(String newName)
```
    Create root of unit.
    
    Parameters:
    
    newName - name of the new unit
    
    Returns:
    
    a new unit representing the square root of the instance
  - multiply
```
public Unit multiply(String newName,
                     Unit other)
```
    Create product of units.
    
    Parameters:
    
    newName - name of the new unit
    
    other - unit to multiply with
    
    Returns:
    
    a new unit representing the this times the other unit
  - divide
```
public Unit divide(String newName,
                   Unit other)
```
    Create quotient of units.
    
    Parameters:
    
    newName - name of the new unit
    
    other - unit to divide with
    
    Returns:
    
    a new unit representing the this divided by the other unit
  - toSI
```
public double toSI(double value)
```
    Convert a value to SI units.
    
    Parameters:
    
    value - value instance unit
    
    Returns:
    
    value in SI units
  - toSI
```
public double toSI(Double value)
```
    Convert a value to SI units.
    
    Parameters:
    
    value - value instance unit
    
    Returns:
    
    value in SI units
  - fromSI
```
public double fromSI(double value)
```
    Convert a value from SI units.
    
    Parameters:
    
    value - value SI unit
    
    Returns:
    
    value in instance units
  - fromSI
```
public double fromSI(Double value)
```
    Convert a value from SI units.
    
    Parameters:
    
    value - value SI unit
    
    Returns:
    
    value in instance units
  - parse
```
public static Unit parse(String unitSpecification)
```
    Parse a unit.
    The grammar for unit specification allows chains units multiplication and division, as well as putting powers on units.
    
    The symbols used for units are the SI units with some extensions.
    
    year
    
    the accepted non-SI unit for Julian year is "a" but we also accept "yr"
    
    day
    
    the accepted non-SI unit for day is "d" but we also accept "day"
    
    dimensionless
    
    both "1" and "#" (U+0023, NUMBER SIGN) are accepted
    
    mass
    
    "g" is the standard symbol, despite the unit is "kg" (it is the only unit that has a prefix in its name, so all multiples must be based on "g")
    
    degrees
    
    the base symbol for degrees is "°" (U+00B0, DEGREE SIGN), but we also accept "◦" (U+25E6, WHITE BULLET) and "deg"
    
    arcminute
    
    The base symbol for arcminute is "′" (U+2032, PRIME) but we also accept "'" (U+0027, APOSTROPHE)
    
    arcsecond
    
    The base symbol for arcsecond is "″" (U+2033, DOUBLE PRIME) but we also accept "''" (two occurrences of U+0027, APOSTROPHE), "\"" (U+0022, QUOTATION MARK) and "as"
    
    All the SI prefix (from "y", yocto, to "Y", Yotta) are accepted, as well as integer prefixes. The standard symbol for micro 10⁻⁶ is "µ" (U+00B5, MICRO SIGN), but we also accept "μ" (U+03BC, GREEK SMALL LETTER MU). Beware that some combinations are forbidden, for example "Pa" is Pascal, not peta-years, and "as" is arcsecond for this parser, not atto-seconds, because many people in the space field use mas for milliarcseconds and µas for microarcseconds. Beware that prefixes are case-sensitive! Integer prefixes can be used to specify units like "30s", but only once at the beginning of the specification (i.e. "2rev/d²" is accepted, but "rev/(2d)²" is refused). Conforming with SI brochure "The International System of Units" (9th edition, 2019), each SI prefix is part of the unit and precedes the unit symbol without a separator (i.e. MHz is seen as one identifier).
    
    multiplication
    
    can specified with either "*" (U+002A, ASTERISK), "×" (U+00D7, MULTIPLICATION SIGN), "." (U+002E, FULL STOP) or "·" (U+00B7, MIDDLE DOT) as the operator
    
    division
    
    can be specified with either "/" (U+002F, SOLIDUS) or "⁄" (U+2044, FRACTION SLASH) as the operator
    
    powers
    
    can be specified either by
    
    prefixing with the unicode "√" (U+221A, SQUARE ROOT) character
    
    postfixing with "**", "^" or implicitly using unicode superscripts
    
    Exponents can be specified in different ways:
    
    as an integer, as in "m^-2" or "m⁻²"
    
    directly as unicode characters for the few fractions that unicode supports, as in "Ω^⅞"
    
    as the special decimal value 0.5 which is used by CCSDS, as in "km**0.5"
    
    as a pair of parentheses surrounding two integers separated by a solidus or fraction slash, as in "Pa^(11/12)"
    
    For integer exponents, the digits must be ASCII digits from the Basic Latin block from unicode if explicit exponent marker "**" or "^" is used, or using unicode superscript digits if implicit exponentiation (i.e. no markers at all) is used. Unicode superscripts are not allowed for fractional exponents because unicode does not provide a superscript solidus. Negative exponents can be used too.
    These rules mean all the following (silly) examples are parsed properly: MHz, km/√d, kg.m.s⁻¹, µas^⅖/(h**(2)×m)³, km/√(kg.s), km**0.5, 2rev/d²
    Parameters:
    
    unitSpecification - unit specification to parse
    
    Returns:
    
    parsed unit
  - equals
```
public boolean equals(Object unit)
```
    Check if the instance represents the same unit as another instance.
    The name is not considered so aliases are considered equal.
    
    Overrides:
    
    equals in class Object
    
    Parameters:
    
    unit - other unit
    
    Returns:
    
    true if the instance and the other unit refer to the same unit
  - hashCode
```
public int hashCode()
```
    Get a hashcode for this unit.
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    
    hashcode
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class Unit

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

NONE

ONE

PERCENT

SECOND

MINUTE

HOUR

DAY

YEAR

HERTZ

METRE

KILOMETRE

KILOGRAM

GRAM

AMPERE

RADIAN

DEGREE

ARC_MINUTE

ARC_SECOND

REVOLUTION

NEWTON

PASCAL

BAR

JOULE

WATT

COULOMB

VOLT

OHM

TESLA

SOLAR_FLUX_UNIT

TOTAL_ELECTRON_CONTENT_UNIT

EARTH_RADII

Constructor Detail

Unit

Method Detail

getName

getScale

getMass

getLength

getTime

getCurrent

getAngle

sameDimension

sameDimensionSI

ensureCompatible

alias

scale

power

sqrt

multiply

divide

toSI

toSI

fromSI

fromSI

parse

equals

hashCode

toString