// $Id: UnitDimension.java,v 1.6 2002/01/29 17:33:43 steve Exp $
/*
 * Copyright 1997-2000 Unidata Program Center/University Corporation for
 * Atmospheric Research, P.O. Box 3000, Boulder, CO 80307,
 * support@unidata.ucar.edu.
 * 
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at
 * your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 
 */
package ucar.units;

/*
 * 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
 * @version $Id: UnitDimension.java,v 1.6 2002/01/29 17:33:43 steve Exp $
 */
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) + '"');
    }
}
