package org.djunits.unit;
   
   import static org.djunits.unit.unitsystem.UnitSystem.CGS;
   import static org.djunits.unit.unitsystem.UnitSystem.IMPERIAL;
   import static org.djunits.unit.unitsystem.UnitSystem.SI_DERIVED;
   
   import org.djunits.unit.unitsystem.UnitSystem;
   
   /**
   * Standard acceleration unit based on distance and time.
   * <p>
   * Copyright (c) 2015-2018 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="http://djunits.org/docs/license.html">DJUNITS License</a>.
   * <p>
   * $LastChangedDate: 2018-01-28 03:17:44 +0100 (Sun, 28 Jan 2018) $, @version $Revision: 256 $, by $Author: averbraeck $,
   * initial version May 15, 2014 <br>
   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   */
  public class AccelerationUnit extends LinearUnit<AccelerationUnit>
  {
      /** */
      private static final long serialVersionUID = 20140607L;
  
      /** the actual length unit, e.g. KILOMETER. */
      private final LengthUnit lengthUnit;
  
      /** the actual time unit, e.g. HOUR. */
      private final DurationUnit durationUnit;
  
      /** The SI unit for acceleration is m/s^2. */
      public static final AccelerationUnit SI;
  
      /** m/s^2. */
      public static final AccelerationUnit METER_PER_SECOND_2;
  
      /** km/h^2. */
      public static final AccelerationUnit KM_PER_HOUR_2;
  
      /** ft/s^2. */
      public static final AccelerationUnit FOOT_PER_SECOND_2;
  
      /** in/s^2. */
      public static final AccelerationUnit INCH_PER_SECOND_2;
  
      /** mi/h^2. */
      public static final AccelerationUnit MILE_PER_HOUR_2;
  
      /** mi/s^2. */
      public static final AccelerationUnit MILE_PER_SECOND_2;
  
      /** kt/s. */
      public static final AccelerationUnit KNOT_PER_SECOND;
  
      /** mi/h/s. */
      public static final AccelerationUnit MILE_PER_HOUR_PER_SECOND;
  
      /** standard gravity. */
      public static final AccelerationUnit STANDARD_GRAVITY;
  
      /** standard gravity. */
      public static final AccelerationUnit GAL;
  
      static
      {
          SI = new AccelerationUnit(LengthUnit.METER, DurationUnit.SECOND, "AccelerationUnit.meter_per_second_squared",
                  "AccelerationUnit.m/s^2", SI_DERIVED, true);
          METER_PER_SECOND_2 = SI;
          KM_PER_HOUR_2 = new AccelerationUnit(LengthUnit.KILOMETER, DurationUnit.HOUR, "AccelerationUnit.km_per_hour_squared",
                  "AccelerationUnit.km/h^2", SI_DERIVED, true);
          FOOT_PER_SECOND_2 = new AccelerationUnit(LengthUnit.FOOT, DurationUnit.SECOND,
                  "AccelerationUnit.foot_per_second_squared", "AccelerationUnit.ft/s^2", IMPERIAL, true);
          INCH_PER_SECOND_2 = new AccelerationUnit(LengthUnit.INCH, DurationUnit.SECOND,
                  "AccelerationUnit.inch_per_second_squared", "AccelerationUnit.in/s^2", IMPERIAL, true);
          MILE_PER_HOUR_2 = new AccelerationUnit(LengthUnit.MILE, DurationUnit.HOUR, "AccelerationUnit.mile_per_hour_squared",
                  "AccelerationUnit.mi/h^2", IMPERIAL, true);
          MILE_PER_SECOND_2 = new AccelerationUnit(LengthUnit.MILE, DurationUnit.SECOND,
                  "AccelerationUnit.mile_per_second_squared", "AccelerationUnit.mi/s^2", IMPERIAL, true);
          KNOT_PER_SECOND = new AccelerationUnit(SpeedUnit.KNOT, DurationUnit.SECOND, "AccelerationUnit.knot_per_second",
                  "AccelerationUnit.kt/s", IMPERIAL, true);
          MILE_PER_HOUR_PER_SECOND = new AccelerationUnit(SpeedUnit.MILE_PER_HOUR, DurationUnit.SECOND,
                  "AccelerationUnit.mile_per_hour_per_second", "AccelerationUnit.mi/h/s", IMPERIAL, true);
          STANDARD_GRAVITY = new AccelerationUnit("AccelerationUnit.standard_gravity", "AccelerationUnit.g", SI_DERIVED,
                  METER_PER_SECOND_2, 9.80665, true);
          GAL = new AccelerationUnit(LengthUnit.CENTIMETER, DurationUnit.SECOND, "AccelerationUnit.gal", "AccelerationUnit.Gal",
                  CGS, true);
      }
  
      /**
       * Define acceleration unit based on length and time. You can define units like meter/second^2 here.
       * @param lengthUnit the unit of length for the acceleration unit, e.g., meter
       * @param durationUnit the unit of time for the acceleration unit, e.g., second
       * @param nameOrNameKey if standardUnit: the key to the locale file for the long name of the unit, otherwise the name itself
       * @param abbreviationOrAbbreviationKey if standardUnit: the key to the locale file for the abbreviation of the unit,
       *            otherwise the abbreviation itself
       * @param unitSystem the unit system, e.g. SI or Imperial
       * @param standardUnit indicates whether it is a standard unit with a definition in the locale, or a user-defined unit
       */
      private AccelerationUnit(final LengthUnit lengthUnit, final DurationUnit durationUnit, final String nameOrNameKey,
              final String abbreviationOrAbbreviationKey, final UnitSystem unitSystem, final boolean standardUnit)
     {
         super(nameOrNameKey, abbreviationOrAbbreviationKey, unitSystem, METER_PER_SECOND_2,
                 lengthUnit.getScaleFactor() / (durationUnit.getScaleFactor() * durationUnit.getScaleFactor()), standardUnit);
         this.lengthUnit = lengthUnit;
         this.durationUnit = durationUnit;
     }
 
     /**
      * Define user defined acceleration unit based on length and time. You can define units like meter/second^2 here.
      * @param lengthUnit the unit of length for the acceleration unit, e.g., meter
      * @param durationUnit the unit of time for the acceleration unit, e.g., second
      * @param name the long name of the unit
      * @param abbreviation the abbreviation of the unit
      * @param unitSystem the unit system, e.g. SI or Imperial
      */
     public AccelerationUnit(final LengthUnit lengthUnit, final DurationUnit durationUnit, final String name,
             final String abbreviation, final UnitSystem unitSystem)
     {
         this(lengthUnit, durationUnit, name, abbreviation, unitSystem, false);
     }
 
     /**
      * Define acceleration unit based on speed and time. You can define units like (mile/hour)/second here.
      * @param speedUnit the unit of speed for the acceleration unit, e.g., knot
      * @param durationUnit the unit of time for the acceleration unit, e.g., second
      * @param nameOrNameKey if standardUnit: the key to the locale file for the long name of the unit, otherwise the name itself
      * @param abbreviationOrAbbreviationKey if standardUnit: the key to the locale file for the abbreviation of the unit,
      *            otherwise the abbreviation itself
      * @param unitSystem the unit system, e.g. SI or Imperial
      * @param standardUnit indicates whether it is a standard unit with a definition in the locale, or a user-defined unit
      */
     private AccelerationUnit(final SpeedUnit speedUnit, final DurationUnit durationUnit, final String nameOrNameKey,
             final String abbreviationOrAbbreviationKey, final UnitSystem unitSystem, final boolean standardUnit)
     {
         super(nameOrNameKey, abbreviationOrAbbreviationKey, unitSystem, METER_PER_SECOND_2,
                 speedUnit.getScaleFactor() / durationUnit.getScaleFactor(), standardUnit);
         this.lengthUnit = speedUnit.getLengthUnit();
         this.durationUnit = durationUnit;
     }
 
     /**
      * Define user-defined acceleration unit based on speed and time. You can define units like (mile/hour)/second here.
      * @param speedUnit the unit of speed for the acceleration unit, e.g., knot
      * @param durationUnit the unit of time for the acceleration unit, e.g., second
      * @param name the long name of the unit
      * @param abbreviation the abbreviation of the unit
      * @param unitSystem the unit system, e.g. SI or Imperial
      */
     public AccelerationUnit(final SpeedUnit speedUnit, final DurationUnit durationUnit, final String name,
             final String abbreviation, final UnitSystem unitSystem)
     {
         this(speedUnit, durationUnit, name, abbreviation, unitSystem, false);
     }
 
     /**
      * Build a unit with a conversion factor to another unit.
      * @param nameOrNameKey if standardUnit: the key to the locale file for the long name of the unit, otherwise the name itself
      * @param abbreviationOrAbbreviationKey if standardUnit: the key to the locale file for the abbreviation of the unit,
      *            otherwise the abbreviation itself
      * @param unitSystem the unit system, e.g. SI or Imperial
      * @param referenceUnit the unit to convert to
      * @param scaleFactorToReferenceUnit multiply a value in this unit by the factor to convert to the given reference unit
      * @param standardUnit indicates whether it is a standard unit with a definition in the locale, or a user-defined unit
      */
     private AccelerationUnit(final String nameOrNameKey, final String abbreviationOrAbbreviationKey,
             final UnitSystem unitSystem, final AccelerationUnit referenceUnit, final double scaleFactorToReferenceUnit,
             final boolean standardUnit)
     {
         super(nameOrNameKey, abbreviationOrAbbreviationKey, unitSystem, referenceUnit, scaleFactorToReferenceUnit,
                 standardUnit);
         this.lengthUnit = referenceUnit.getLengthUnit();
         this.durationUnit = referenceUnit.getDurationUnit();
     }
 
     /**
      * Build a user-defined unit with a conversion factor to another unit.
      * @param name the long name of the unit
      * @param abbreviation the abbreviation of the unit
      * @param unitSystem the unit system, e.g. SI or Imperial
      * @param referenceUnit the unit to convert to
      * @param scaleFactorToReferenceUnit multiply a value in this unit by the factor to convert to the given reference unit
      */
     public AccelerationUnit(final String name, final String abbreviation, final UnitSystem unitSystem,
             final AccelerationUnit referenceUnit, final double scaleFactorToReferenceUnit)
     {
         this(name, abbreviation, unitSystem, referenceUnit, scaleFactorToReferenceUnit, false);
     }
 
     /**
      * @return lengthUnit
      */
     public final LengthUnit getLengthUnit()
     {
         return this.lengthUnit;
     }
 
     /**
      * @return durationUnit
      */
     public final DurationUnit getDurationUnit()
     {
         return this.durationUnit;
     }
 
     /** {@inheritDoc} */
     @Override
     public final AccelerationUnit getStandardUnit()
     {
         return METER_PER_SECOND_2;
     }
 
     /** {@inheritDoc} */
     @Override
     public final String getSICoefficientsString()
     {
         return "m/s2";
     }
 
 }