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The ucar.units Java package is for decoding and encoding formatted unit specifications (e.g. "m/s"), converting numeric values between compatible units (e.g. between "m/s" and "knot"), and for performing arithmetic operations on units (e.g. dividing one unit by another, or raising a unit to a power).

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/*
 * Copyright (c) 1998-2018 University Corporation for Atmospheric Research/Unidata
 * See LICENSE for license information.
 */
package ucar.units;


import javax.annotation.concurrent.Immutable;

/*
 * Provides support for the concept of the dimension of a unit.  The
 * dimension of a unit is like the dimension of a quantity except that
 * the individual quantity dimensions have been replaced with the
 * corresponding base unit.  For example, the dimension of the quantity
 * "force" is "M.L.t-2" and the dimension of the corresponding SI unit
 * (the "newton") is "kg.m.s-2".
 *
 * Instances of this class are immutable.
 *
 * @author Steven R. Emmerson
 */
@Immutable
public final class
UnitDimension
    extends	Dimension
{
    /**
     * Constructs a dimensionless unit dimension.
     */
    public
    UnitDimension()
    {
	super();
    }

    /**
     * Constructs the unit dimension corresponding to a base unit.
     * @param baseUnit		A base unit.
     */
    public
    UnitDimension(BaseUnit baseUnit)
    {
	super(new Factor(baseUnit));
    }

    /**
     * Constructs a unit dimension comprised of the given factors.
     * @param factors		The factors that constitute the unit dimension.
     */
    private
    UnitDimension(Factor[] factors)
    {
	super(factors);
    }

    /**
     * Multiplies this unit dimension by another.
     * @param that		The other unit dimension.
     * @return			The product of this unit dimension multiplied
     *				by the other.
     */
    public UnitDimension
    multiplyBy(UnitDimension that)
    {
	return new UnitDimension(mult(that));
    }

    /**
     * Divides this unit dimension by another.
     * @param that		The other unit dimension.
     * @return			The quotient of this unit dimension divided
     *				by the other.
     */
    public UnitDimension
    divideBy(UnitDimension that)
    {
	return multiplyBy(that.raiseTo(-1));
    }

    /**
     * Raises this unit dimension to a power.
     * @param power		The power.
     * @return			The result of raising this unit dimension
     *				to the power.
     */
    public UnitDimension
    raiseTo(int power)
    {
	return new UnitDimension(pow(power));
    }

    /**
     * Returns the corresponding quantity dimension.
     * @return			The quantity dimension corresponding to this
     *				unit dimension.
     */
    public QuantityDimension
    getQuantityDimension()
    {
	Factor[]	factors = getFactors();
	for (int i = factors.length; --i >= 0; )
	{
	    Factor	factor = factors[i];
	    factors[i] =
		new Factor(
		    ((BaseUnit)factor.getBase()).getBaseQuantity(), 
		    factor.getExponent());
	}
	return new QuantityDimension(factors);
    }

    /**
     * Tests this class.
     */
    public static void
    main(String[] args)
	throws	Exception
    {
	System.out.println("new UnitDimension() = \"" +
	    new UnitDimension() + '"');
	UnitDimension	timeDimension =
	    new UnitDimension(
		BaseUnit.getOrCreate(
		    UnitName.newUnitName("second", null, "s"),
		    BaseQuantity.TIME));
	System.out.println("timeDimension = \"" + timeDimension + '"');
	UnitDimension	lengthDimension =
	    new UnitDimension(
		BaseUnit.getOrCreate(
		    UnitName.newUnitName("meter", null, "m"),
		    BaseQuantity.LENGTH));
	System.out.println("lengthDimension = \"" + lengthDimension + '"');
	System.out.println(
	    "lengthDimension.isReciprocalOf(timeDimension) = \"" +
	    lengthDimension.isReciprocalOf(timeDimension) + '"');
	UnitDimension	hertzDimension = timeDimension.raiseTo(-1);
	System.out.println("hertzDimension = \"" + hertzDimension + '"');
	System.out.println(
	    "hertzDimension.isReciprocalOf(timeDimension) = \"" +
	    hertzDimension.isReciprocalOf(timeDimension) + '"');
	System.out.println("lengthDimension.divideBy(timeDimension) = \"" +
	    lengthDimension.divideBy(timeDimension) + '"');
	System.out.println(
	    "lengthDimension.divideBy(timeDimension).raiseTo(2) = \"" +
	    lengthDimension.divideBy(timeDimension).raiseTo(2) + '"');
    }
}