TimeUnit.java
package org.djunits.unit;
import static org.djunits.unit.unitsystem.UnitSystem.OTHER;
import java.util.GregorianCalendar;
import org.djunits.unit.unitsystem.UnitSystem;
/**
* Standard absolute time units. Note that when the offset of a stored absolute Time becomes large, precision of a float or
* double might not be enough for the required resolution of a Time. A float has around 7 significant digits (23 bit mantissa),
* whereas a double has around 16 significant digits (52 bit mantissa). This means that when we need to have a float time that
* is precise to microseconds, the Time value should not go above 2^22 = 4.0E6. This is <b>not</b> enough to store Epoch values!
* So feeding System.TimeInMillis() to a FloatTime with TimeUnit.BASE as its unit is not having the required precision. For a
* (double) Time with TimeUnit.BASE as its unit, the largest value where the ms precision is reached is 2^51 = 2.3E15, which is
* around 71000 years. This is sufficient to store a date on an Epoch level precise to a ms.
* <p>
* Copyright (c) 2015-2019 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: 2019-03-02 19:06:46 +0100 (Sat, 02 Mar 2019) $, @version $Revision: 342 $, by $Author: averbraeck $,
* initial version May 15, 2014 <br>
* @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
*/
public class TimeUnit extends AbsoluteLinearUnit<TimeUnit, DurationUnit>
{
/** */
private static final long serialVersionUID = 20140607L;
/**
* The base unit for time with an artifical "zero" point.
*/
public static final TimeUnit BASE;
/**
* The base unit for time with an artifical "zero" point with a calculation in seconds. Note that when the offset becomes
* large, precision of a float or double might not be enough for the required resolution of a Time. A float has around 7
* significant digits (23 bit mantissa), whereas a double has around 16 significant digits (52 bit mantissa). This means
* that when we need to have a float time that is precise to microseconds, the Time value should not go above 2^22 = 4.0E6.
* This is <b>not</b> enough to store Epoch values! So feeding System.TimeInMillis() to a FloatTime with TimeUnit.BASE as
* its unit is not having the required precision. For a (double) Time with TimeUnit.BASE as its unit, the largest value
* where the ms precision is reached is 2^51 = 2.3E15, which is around 71000 years. This is sufficient to store a date on an
* Epoch level precise to a ms.
*/
public static final TimeUnit BASE_SECOND;
/** The base unit for time with an artifical "zero" point with a calculation in microseconds. */
public static final TimeUnit BASE_MICROSECOND;
/** The base unit for time with an artifical "zero" point with a calculation in milliseconds. */
public static final TimeUnit BASE_MILLISECOND;
/** The base unit for time with an artifical "zero" point with a calculation in minutes. */
public static final TimeUnit BASE_MINUTE;
/** The base unit for time with an artifical "zero" point with a calculation in hours. */
public static final TimeUnit BASE_HOUR;
/** The base unit for time with an artifical "zero" point with a calculation in days. */
public static final TimeUnit BASE_DAY;
/** The base unit for time with an artifical "zero" point with a calculation in weeks. */
public static final TimeUnit BASE_WEEK;
/**
* The POSIX and Gregorian Epoch: January 1, 1970 at 00:00 UTC with a calculation in seconds. The base should be taken in
* such a way that a resolution of a millisecond is still 'visible' on a date in, say, 2020. When 1-1-1970 is used as the
* origin, 1-1-2020 has a value of 1,577,836,800,000 milliseconds = 1.6E12 ms. If we want to be precise on the ms level, we
* need 12 significant digits. A float has around 7 significant digits (23 bit mantissa), whereas a double has around 16
* significant digits (52 bit mantissa). This means that a float time with an offset of 1-1-1970 is at best precise to a
* minute level. A double time is precise to microseconds. Therefore, avoid using float times that use the EPOCH.
*/
public static final TimeUnit EPOCH;
/** The POSIX and Gregorian Epoch: January 1, 1970 at 00:00 UTC with a calculation in seconds. */
public static final TimeUnit EPOCH_SECOND;
/** The POSIX and Gregorian Epoch: January 1, 1970 at 00:00 UTC with a calculation in microseconds. */
public static final TimeUnit EPOCH_MICROSECOND;
/** The POSIX and Gregorian Epoch: January 1, 1970 at 00:00 UTC with a calculation in milliseconds. */
public static final TimeUnit EPOCH_MILLISECOND;
/** The POSIX and Gregorian Epoch: January 1, 1970 at 00:00 UTC with a calculation in minutes. */
public static final TimeUnit EPOCH_MINUTE;
/** The POSIX and Gregorian Epoch: January 1, 1970 at 00:00 UTC with a calculation in hours. */
public static final TimeUnit EPOCH_HOUR;
/** The POSIX and Gregorian Epoch: January 1, 1970 at 00:00 UTC with a calculation in days. */
public static final TimeUnit EPOCH_DAY;
/** The POSIX and Gregorian Epoch: January 1, 1970 at 00:00 UTC with a calculation in weeks. */
public static final TimeUnit EPOCH_WEEK;
/**
* The Epoch with 0001-01-01 AD at 00:00 as the origin with a calculation in seconds. When 1-1-0001 is used as the origin,
* 1-1-2020 has a value of around 6.4E13 ms. If we want to be precise on the ms level, we need 13 significant digits. A
* float has around 7 significant digits (23 bit mantissa), whereas a double has around 16 significant digits (52 bit
* mantissa). This means that a float time with an offset of 1-1-0001 is at best precise to an hour level. A double time is
* precise to microseconds. Therefore, avoid using float times that use the EPOCH_YEAR_1.
*/
public static final TimeUnit EPOCH_YEAR_1;
/**
* The Epoch with J2000.0 as the origin, which is The Gregorian date January 1, 2000 at 12:00 GMT (noon) with a calculation
* in seconds. When 1-1-2000 is used as the origin, 1-1-2020 has a value of around 6.3E11 ms. If we want to be precise on
* the ms level, we need 11 significant digits. A float has around 7 significant digits (23 bit mantissa), whereas a double
* has around 16 significant digits (52 bit mantissa). This means that a float time with an offset of 1-1-2000 is at best
* precise to a minute level. A double time is precise to fractions of microseconds. Therefore, avoid using float times that
* use the EPOCH_J2000_1.
*/
public static final TimeUnit EPOCH_J2000_1;
static
{
BASE = new TimeUnit("TimeUnit.epoch.s", OTHER, 1.0, 0.0, DurationUnit.SECOND);
EPOCH = BASE;
EPOCH_SECOND = BASE;
BASE_SECOND = EPOCH_SECOND;
EPOCH_MICROSECOND = new TimeUnit("TimeUnit.epoch.mus", OTHER, 1E-6, 0.0, DurationUnit.MICROSECOND);
BASE_MICROSECOND = EPOCH_MICROSECOND;
EPOCH_MILLISECOND = new TimeUnit("TimeUnit.epoch.ms", OTHER, 1E-3, 0.0, DurationUnit.MILLISECOND);
BASE_MILLISECOND = EPOCH_MILLISECOND;
EPOCH_MINUTE = new TimeUnit("TimeUnit.epoch.m", OTHER, 60.0, 0.0, DurationUnit.MINUTE);
BASE_MINUTE = EPOCH_MINUTE;
EPOCH_HOUR = new TimeUnit("TimeUnit.epoch.h", OTHER, 3600.0, 0.0, DurationUnit.HOUR);
BASE_HOUR = EPOCH_HOUR;
EPOCH_DAY = new TimeUnit("TimeUnit.epoch.d", OTHER, 3600 * 24.0, 0.0, DurationUnit.DAY);
BASE_DAY = EPOCH_DAY;
EPOCH_WEEK = new TimeUnit("TimeUnit.epoch.w", OTHER, 3600 * 24 * 7.0, 0.0, DurationUnit.WEEK);
BASE_WEEK = EPOCH_WEEK;
double seconds00010101 = new GregorianCalendar(1, 0, 1, 0, 0, 0).getTimeInMillis() / 1000.0;
EPOCH_YEAR_1 = new TimeUnit("TimeUnit.epoch_1", "TimeUnit.epoch_1", OTHER, 1.0, seconds00010101, DurationUnit.SECOND);
double seconds20000101 = new GregorianCalendar(2000, 0, 1, 12, 0, 0).getTimeInMillis() / 1000.0;
EPOCH_J2000_1 =
new TimeUnit("TimeUnit.epoch_j2000", "TimeUnit.epoch_j2000", OTHER, 1.0, seconds20000101, DurationUnit.SECOND);
}
/**
* Build a TimeUnit with a scale factor and offset to the base TimeUnit.
* @param abbreviationKey String; the key to the locale file for the abbreviation of the unit
* @param unitSystem UnitSystem; the unit system, e.g. SI or Imperial
* @param scaleFactor double; multiply a value in this unit by the factor to convert to the given reference unit
* @param offset double; the offset to the reference unit to add to convert to the standard (e.g., BASE) unit
* @param relativeUnit DurationUnit; the corresponding relative unit belonging to this absolute unit
*/
private TimeUnit(final String abbreviationKey, final UnitSystem unitSystem, final double scaleFactor, final double offset,
final DurationUnit relativeUnit)
{
super(abbreviationKey, unitSystem, scaleFactor, offset, relativeUnit);
}
/**
* Build a user-defined TimeUnit with a scale factor and offset to the base TimeUnit.
* @param name String; the long name of the unit
* @param abbreviation String; the abbreviation of the unit
* @param unitSystem UnitSystem; the unit system, e.g. SI or Imperial
* @param scaleFactor double; multiply a value in this unit by the factor to convert to the given reference unit
* @param offset double; the offset to the reference unit to add to convert to the standard (e.g., BASE) unit
* @param relativeUnit DurationUnit; the corresponding relative unit belonging to this absolute unit
*/
public TimeUnit(final String name, final String abbreviation, final UnitSystem unitSystem, final double scaleFactor,
final double offset, final DurationUnit relativeUnit)
{
super(name, abbreviation, unitSystem, scaleFactor, offset, relativeUnit);
}
/** {@inheritDoc} */
@Override
public final TimeUnit getStandardUnit()
{
return BASE;
}
/** {@inheritDoc} */
@Override
public final String getSICoefficientsString()
{
return "s";
}
}