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Entity > Abstract > Quantity > PhysicalQuantity > ConstantQuantity > SolidAngleMeasure > Steradian |
Steradian comparison table |
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SolidAngleMeasure | A ConstantQuantity is a PhysicalQuantity which has a constant value, e.g. 3 meters and 5 hours. The magnitude (see MagnitudeFn) of every ConstantQuantity is a RealNumber. ConstantQuantities are distinguished from FunctionQuantities, which map ConstantQuantities to other ConstantQuantities. All ConstantQuantites are expressed with the BinaryFunction MeasureFn, which takes a Number and a UnitOfMeasure as arguments. For example, 3 Meters can be expressed as (MeasureFn 3 Meter). ConstantQuantities form a partial order (see PartialOrderingRelation) with the lessThan relation, since lessThan is a RelationExtendedToQuantities and lessThan is defined over the RealNumbers. The lessThan relation is not a total order (see TotalOrderingRelation) over the class ConstantQuantity since elements of some subclasses of ConstantQuantity (such as length quantities) are incomparable to elements of other subclasses of ConstantQuantity (such as mass quantities) | ConstantQuantity | measure | MagnitudeFn | (=> | |
SystemeInternationalUnit | The Class of Systeme International (SI) units | UnitOfMeasure | MeasureFn | SubtractionFn | (=> | |
Steradian | SystemeInternationalUnit | SI SolidAngleMeasure. Symbol: sr. It is the solid angle of a sphere subtended by a portion of the surface whose area is equal to the square of the sphere's radius. Another definition is: the solid angle which, having its vertex in the center of the sphere, cuts off an area of the surface of the sphere equal to that of a square with sides of length equal to the radius of the sphere. Steradian = m^2/m^2 = 1 | MeasureFn | MagnitudeFn | (=> |