Class Unit
- java.lang.Object
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- org.orekit.utils.units.Unit
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- 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
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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.
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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.<T extends CalculusFieldElement<T>>
TfromSI(T 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.<T extends CalculusFieldElement<T>>
TtoSI(T value)
Convert a value to SI units.String
toString()
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Field Detail
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NONE
public static final Unit NONE
No unit.
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ONE
public static final Unit ONE
Dimensionless unit.
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PERCENT
public static final Unit PERCENT
Percentage unit.
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SECOND
public static final Unit SECOND
Second unit.
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MINUTE
public static final Unit MINUTE
Minute unit.
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HOUR
public static final Unit HOUR
Hour unit.
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DAY
public static final Unit DAY
Day unit.
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YEAR
public static final Unit YEAR
Julian year unit.- See Also:
- SI Units at IAU
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HERTZ
public static final Unit HERTZ
Hertz unit.
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METRE
public static final Unit METRE
Metre unit.
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KILOMETRE
public static final Unit KILOMETRE
Kilometre unit.
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KILOGRAM
public static final Unit KILOGRAM
Kilogram unit.
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GRAM
public static final Unit GRAM
Gram unit.
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AMPERE
public static final Unit AMPERE
Ampere unit.
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RADIAN
public static final Unit RADIAN
Radian unit.
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DEGREE
public static final Unit DEGREE
Degree unit.
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ARC_MINUTE
public static final Unit ARC_MINUTE
Arc minute unit.
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ARC_SECOND
public static final Unit ARC_SECOND
Arc second unit.
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REVOLUTION
public static final Unit REVOLUTION
Revolution unit.
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NEWTON
public static final Unit NEWTON
Newton unit.
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PASCAL
public static final Unit PASCAL
Pascal unit.
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BAR
public static final Unit BAR
Bar unit.
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JOULE
public static final Unit JOULE
Joule unit.
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WATT
public static final Unit WATT
Watt unit.
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COULOMB
public static final Unit COULOMB
Coulomb unit.
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VOLT
public static final Unit VOLT
Volt unit.
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OHM
public static final Unit OHM
Ohm unit.
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TESLA
public static final Unit TESLA
tesla unit.
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SOLAR_FLUX_UNIT
public static final Unit SOLAR_FLUX_UNIT
Solar Flux Unit.
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TOTAL_ELECTRON_CONTENT_UNIT
public static final Unit TOTAL_ELECTRON_CONTENT_UNIT
Total Electron Content Unit.
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EARTH_RADII
public static final Unit EARTH_RADII
Earth Radii used as Bstar unit in CCSDS OMM.
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Constructor Detail
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Unit
public Unit(String name, double scale, Fraction mass, Fraction length, Fraction time, Fraction current, Fraction angle)
Simple constructor.- Parameters:
name
- name of the unitscale
- scaling factor to SI unitsmass
- mass exponentlength
- length exponenttime
- time exponentcurrent
- current exponentangle
- angle exponent
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Method Detail
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getName
public String getName()
Get the name of the unit.- Returns:
- name of the unit
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getScale
public double getScale()
Get the scaling factor to SI units.- Returns:
- scaling factor to SI units
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getMass
public Fraction getMass()
Get the mass exponent.- Returns:
- mass exponent
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getLength
public Fraction getLength()
Get the length exponent.- Returns:
- length exponent
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getTime
public Fraction getTime()
Get the time exponent.- Returns:
- time exponent
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getCurrent
public Fraction getCurrent()
Get the current exponent.- Returns:
- current exponent
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getAngle
public Fraction getAngle()
Get the angle exponent.- Returns:
- angle exponent
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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
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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
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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 unitsunits
- units to checkallowScaleDifferences
- if true, unit with same dimension but different scale (likeKILOMETRE
versusMETRE
) are allowed, otherwise they will trigger an exception- Throws:
OrekitException
- if units are not compatible (number of elements, dimensions or scaling)
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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
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scale
public Unit scale(String newName, double factor)
Scale a unit.- Parameters:
newName
- name of the new unitfactor
- scaling factor- Returns:
- a new unit representing scale times the instance
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power
public Unit power(String newName, Fraction exponent)
Create power of unit.- Parameters:
newName
- name of the new unitexponent
- exponent to apply- Returns:
- a new unit representing the power of the instance
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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
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multiply
public Unit multiply(String newName, Unit other)
Create product of units.- Parameters:
newName
- name of the new unitother
- unit to multiply with- Returns:
- a new unit representing the this times the other unit
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divide
public Unit divide(String newName, Unit other)
Create quotient of units.- Parameters:
newName
- name of the new unitother
- unit to divide with- Returns:
- a new unit representing the this divided by the other unit
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toSI
public double toSI(double value)
Convert a value to SI units.- Parameters:
value
- value instance unit- Returns:
- value in SI units
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toSI
public double toSI(Double value)
Convert a value to SI units.- Parameters:
value
- value instance unit- Returns:
- value in SI units
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toSI
public <T extends CalculusFieldElement<T>> T toSI(T value)
Convert a value to SI units.- Type Parameters:
T
- type of the field elements- Parameters:
value
- value instance unit- Returns:
- value in SI units
- Since:
- 12.1
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fromSI
public double fromSI(double value)
Convert a value from SI units.- Parameters:
value
- value SI unit- Returns:
- value in instance units
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fromSI
public double fromSI(Double value)
Convert a value from SI units.- Parameters:
value
- value SI unit- Returns:
- value in instance units
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fromSI
public <T extends CalculusFieldElement<T>> T fromSI(T value)
Convert a value from SI units.- Type Parameters:
T
- type of the field elements- Parameters:
value
- value SI unit- Returns:
- value in instance units
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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)"
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
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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.
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hashCode
public int hashCode()
Get a hashcode for this unit.
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