Package org.djunits.unit.si

Class SIDimensions

java.lang.Object
org.djunits.unit.si.SIDimensions
All Implemented Interfaces:
Serializable
public class SIDimensions extends Object implements Serializable
SIDimensions stores the dimensionality of a unit using the SI standards. Angle (rad) and solid angle (sr) have been added to be able to specify often used units regarding rotation.

Copyright (c) 2019-2025 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved.
BSD-style license. See DJUNITS License

Author:
Alexander Verbraeck
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final SIDimensions
    DIMLESS
    the dimensionless SIDimensions.
    static final int
    NUMBER_DIMENSIONS
    The (currently) 9 dimensions we take into account: rad, sr, kg, m, s, A, K, mol, cd.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
     
    SIDimensions(byte[] dimensions)
    Create an immutable SIDimensions instance based on a safe copy of a given dimensions specification.
    protected
    SIDimensions(byte[] numerator, byte[] denominator)
    Create an immutable fractional SIDimensions instance based on a safe copy of a given specification, separated in a numerator and a denominator.
     
    SIDimensions(int angle, int solidAngle, int mass, int length, int time, int current, int temperature, int amountOfSubstance, int luminousIntensity)
    Create an immutable SIDimensions instance based on a safe copy of a given dimensions specification.

  • Method Summary

    Modifier and Type
    Method
    Description
    static SIDimensions
    add(SIDimensions dim1, SIDimensions dim2)
    Add two SIDimensions and return the new SIDimensions.
    boolean
    equals(Object obj)
     
    int
    hashCode()
     
    SIDimensions
    invert()
    Invert a set of SI dimensions; instead of m/s we get s/m.
    boolean
    isFractional()
    Indicate whether this SIDImensions contains one or more fractional dimensions.
    SIDimensions
    minus(SIDimensions other)
    Subtract a set of SI dimensions from this SIDimensions.
    static SIDimensions
    of(String siString)
    Parse a string representing SI dimensions to an SIDimensions object.
    SIDimensions
    plus(SIDimensions other)
    Add a set of SI dimensions to this SIDimensions.
    String[]
    siAbbreviations()
    Returns a safe copy of the SI abbreviations (a public static final String[] is mutable).
    double[]
    siDimensions()
    Return the (fractional) SI dimensions in the order rad, sr, kg, m, s, A, K, mol, cd.
    static SIDimensions
    subtract(SIDimensions dim1, SIDimensions dim2)
    Subtract an SIDimensions (dim2) from another SIDimensions (dim1) and return the new SIDimensions.
    String
    toHTMLString(boolean divided, boolean separator)
    Return a string such as "kgm/s2" or or "kg.m.s-2" from this SIDimensions.
    String
    toString()
     
    String
    toString(boolean divided, boolean separator)
    Return a string such as "kgm/s2" or "kg.m/s2" or "kg.m.s-2" from this SIDimensions.
    String
    toString(boolean divided, boolean separator, boolean power)
    Return a string such as "kgm/s2" or "kg.m/s^2" or "kg.m.s^-2" from this SIDimensions.
    String
    toString(boolean divided, String separator, String powerPrefix, String powerPostfix)
    Return a string such as "kgm/s2" or "kg.m/s^2" or "kg.m.s^-2" from this SIDimensions.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • NUMBER_DIMENSIONS

      public static final int NUMBER_DIMENSIONS
      The (currently) 9 dimensions we take into account: rad, sr, kg, m, s, A, K, mol, cd.
      See Also:

    • DIMLESS

      public static final SIDimensions DIMLESS
      the dimensionless SIDimensions.

  • Constructor Details

    • SIDimensions

      public SIDimensions(byte[] dimensions)
      Create an immutable SIDimensions instance based on a safe copy of a given dimensions specification. As an example, speed is indicated as length = 1; time = -1 with the other dimensions equal to zero.
      Parameters:
      dimensions - The (currently) 9 dimensions of the SI unit we distinguish: 0: angle (rad), 1: solid angle (sr), 2: mass (kg), 3: length (m), 4: time (s), 5: current (A), 6: temperature (K), 7: amount of substance (mol), 8: luminous intensity (cd).

    • SIDimensions

      protected SIDimensions(byte[] numerator, byte[] denominator)
      Create an immutable fractional SIDimensions instance based on a safe copy of a given specification, separated in a numerator and a denominator.
      Parameters:
      numerator - The (currently) 9 dimensions of the SI unit we distinguish: 0: angle (rad), 1: solid angle (sr), 2: mass (kg), 3: length (m), 4: time (s), 5: current (A), 6: temperature (K), 7: amount of substance (mol), 8: luminous intensity (cd).
      denominator - The (currently) 9 dimensions of the SI unit we distinguish: 0: angle (rad), 1: solid angle (sr), 2: mass (kg), 3: length (m), 4: time (s), 5: current (A), 6: temperature (K), 7: amount of substance (mol), 8: luminous intensity (cd).

    • SIDimensions

      public SIDimensions(int angle, int solidAngle, int mass, int length, int time, int current, int temperature, int amountOfSubstance, int luminousIntensity)
      Create an immutable SIDimensions instance based on a safe copy of a given dimensions specification.
      Parameters:
      angle - dimension of the angle (rad)
      solidAngle - dimension of the solidAngle (sr)
      mass - dimension of the mass (kg)
      length - dimension of the length (m)
      time - dimension of the time (s)
      current - dimension of the current (A)
      temperature - dimension of the temperature (K)
      amountOfSubstance - dimension of the amount of substance (mol)
      luminousIntensity - dimension of the luminous intensity (cd)

  • Method Details

    • of

      public static SIDimensions of(String siString) throws UnitException
      Parse a string representing SI dimensions to an SIDimensions object. Example: SIDimensions.of("kgm/s2") and SIDimensions.of("kgms-2") will both be translated to a dimensions object with vector {0,0,1,1,-2,0,0,0,0}. It is allowed to use 0 or 1 for the dimensions. Having the same unit in the numerator and the denominator is not seen as a problem: the values are subtracted from each other, so m/m will have a length dimensionality of 0. Dimensions between -9 and 9 are allowed. Spaces, periods and ^ are taken out, but other characters are not allowed and will lead to a UnitException. The order of allowed units is arbitrary, so "kg/ms2" is accepted as well as "kg/s^2.m".
      Parameters:
      siString - the string to parse
      Returns:
      the corresponding SI dimensions
      Throws:
      UnitException - when the string could not be parsed into dimensions

    • siAbbreviations

      public String[] siAbbreviations()
      Returns a safe copy of the SI abbreviations (a public static final String[] is mutable).
      Returns:
      a safe copy of the SI abbreviations

    • siDimensions

      public double[] siDimensions()
      Return the (fractional) SI dimensions in the order rad, sr, kg, m, s, A, K, mol, cd.
      Returns:
      the (fractional) SI dimensions in the order rad, sr, kg, m, s, A, K, mol, cd

    • plus

      public SIDimensions plus(SIDimensions other)
      Add a set of SI dimensions to this SIDimensions. Note: as dimensions are considered to be immutable, a new dimension is returned. The original dimension (this) remains unaltered.
      Parameters:
      other - the dimensions to add (usually as a result of multiplication of scalars)
      Returns:
      the new dimensions with the dimensions of this object plus the dimensions in the parameter

    • minus

      public SIDimensions minus(SIDimensions other)
      Subtract a set of SI dimensions from this SIDimensions. Note: as dimensions are considered to be immutable, a new dimension is returned. The original dimension (this) remains unaltered.
      Parameters:
      other - the dimensions to subtract (usually as a result of division of scalars)
      Returns:
      the new dimensions with the dimensions of this object minus the dimensions in the parameter

    • invert

      public SIDimensions invert()
      Invert a set of SI dimensions; instead of m/s we get s/m. Note: as dimensions are considered to be immutable, a new dimension is returned. The original dimension (this) remains unaltered.
      Returns:
      the new dimensions that are the inverse of the dimensions in this object

    • add

      public static SIDimensions add(SIDimensions dim1, SIDimensions dim2)
      Add two SIDimensions and return the new SIDimensions. Usually, dimensions are added as a result of multiplication of scalars.
      Parameters:
      dim1 - the first set of dimensions
      dim2 - the second set of dimensions
      Returns:
      the new dimensions with the sum of the dimensions in the parameters

    • subtract

      public static SIDimensions subtract(SIDimensions dim1, SIDimensions dim2)
      Subtract an SIDimensions (dim2) from another SIDimensions (dim1) and return the new SIDimensions. Usually, dimensions are added as a result of division of scalars.
      Parameters:
      dim1 - the first set of dimensions
      dim2 - the second set of dimensions that will be subtracted from dim1
      Returns:
      the new dimensions with the difference of the dimensions in the parameters

    • isFractional

      public boolean isFractional()
      Indicate whether this SIDImensions contains one or more fractional dimensions.
      Returns:
      whether this SIDImensions contains one or more fractional dimensions

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object

    • toString

      public String toString(boolean divided, String separator, String powerPrefix, String powerPostfix)
      Return a string such as "kgm/s2" or "kg.m/s^2" or "kg.m.s^-2" from this SIDimensions.
      Parameters:
      divided - if true, return m/s2 for acceleration; if false return ms-2
      separator - add this string between successive units, e.g. kg.m.s-2 instead of kgms-2
      powerPrefix - the prefix for the power, e.g., "^" or "<sup>"
      powerPostfix - the postfix for the power, e.g., "</sup>"
      Returns:
      a formatted string for this SIDimensions

    • toString

      public String toString(boolean divided, boolean separator)
      Return a string such as "kgm/s2" or "kg.m/s2" or "kg.m.s-2" from this SIDimensions.
      Parameters:
      divided - if true, return m/s2 for acceleration; if false return ms-2
      separator - if true, add a period between successive units, e.g. kg.m.s-2 instead of kgms-2
      Returns:
      a formatted string describing this SIDimensions

    • toString

      public String toString(boolean divided, boolean separator, boolean power)
      Return a string such as "kgm/s2" or "kg.m/s^2" or "kg.m.s^-2" from this SIDimensions.
      Parameters:
      divided - if true, return m/s2 for acceleration; if false return ms-2
      separator - if true, add a period between successive units, e.g. kg.m.s-2 instead of kgms-2
      power - if true, add a ^ sign before the power, e.g., "kg.m^2/s^3" instead of "kg.m2/s3"
      Returns:
      a formatted string describing this SIDimensions

    • toHTMLString

      public String toHTMLString(boolean divided, boolean separator)
      Return a string such as "kgm/s2" or or "kg.m.s-2" from this SIDimensions.
      Parameters:
      divided - if true, return "m/s2" for acceleration; if false return "ms-2"
      separator - if true, add a period between successive units, e.g. kg.m.s-2
      Returns:
      a formatted string describing this SIDimensions

    • toString

      public String toString()
      Overrides:
      toString in class Object