org.djunits.unit

Interface AbsoluteUnit

All Known Implementing Classes:

AbsoluteLinearUnit, AbsoluteTemperatureUnit, DirectionUnit, PositionUnit, TimeUnit

public interface AbsoluteUnit

An absolute unit is a unit that needs to be defined with a "distance" to the reference absolute unit. E.g., for Time, an absolute reference unit has to be chosen such as an Epoch (e.g., 0001-01-01 AD at 00:00), where other TimeUnits can be defined relative to that reference unit (e.g., POSIX time, 1-1-1970 at 00:00, which is 719162 days after the reference time).

An absolute unit is always a unit with an OffsetLinearScale. The offset defines how far away the origin of that absolute unit is compared to the base unit. The linear scale indicates in what default "steps" compared to the reference relative scale the absolute scale is used. For temperature, this is very clear. Degrees Celcius is shifted 273.15 compared to the origin of the Kelvin scale, and the linear unit is 1 (relatively, 1 Kelvin is one degree Celcius). For Degree Fahrenheit, the linear scale is 5/9, and the offset is 459.67. For Direction, North can be chosen as 0, and radians (SI) as the default angle. But one could also define a NORTH_DEGREES absolute direction unit, or a WEST_RADIANS one. Similar choices can be made for time and position.

Copyright (c) 2013-2018 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved.
BSD-style license. See DJUNITS License.

$LastChangedDate: 2015-07-24 02:58:59 +0200 (Fri, 24 Jul 2015) $, @version $Revision: 1147 $, by $Author: averbraeck $, initial version Apr 27, 2017

Author:

Alexander Verbraeck, Peter Knoppers

Method Summary

Modifier and Type	Method and Description
double	getOffset() Return the offset to transform to the standard (reference) unit.
double	getScaleFactor() Return the scale factor to transform to the standard (reference) unit.

Method Detail

getScaleFactor

double getScaleFactor()

Return the scale factor to transform to the standard (reference) unit. Multiply by this number to convert to the standard (e.g., SI) unit. For Degrees Fahrenheit, the linear scale factor is 5/9 to convert it to Kelvin, the standard unit.

Returns:

double; the scale factor to transform to the standard (reference) unit.

getOffset

double getOffset()

Return the offset to transform to the standard (reference) unit. Add this number before scaling to convert to the standard (e.g., SI) unit. For Degrees Fahrenheit, the offset is 459.67 to convert it to Kelvin, the standard unit.

Returns:

double; the offset to transform to the standard (reference) unit.