**Defined in theory: Physical-quantities****Source code: physical-quantities.lisp**

**Documentation:**magnitude-in-system-of-units is like magnitude, but it maps a quantity and a

*system*of units into a numeric value (a dimensionless-quantity). For example, one could ask for the value of 55 miles per hour in the SI system. In SI, the standard-unit for the dimension of miles per hour is meters per second-of-time. So the answer would be about 24 meters per second-of-time.**Arity:**3

(Nth-Domain Magnitude-In-System-Of-Units 3 Dimensionless-Quantity) (Nth-Domain Magnitude-In-System-Of-Units 2 System-Of-Units) (Nth-Domain Magnitude-In-System-Of-Units 1 Constant-Quantity) (=> (Magnitude-In-System-Of-Units ?Q ?System ?Mag) (= ?Mag (Magnitude ?Q (Standard-Unit ?System (Quantity.Dimension ?Q)))))