Locus Command
 Locus( <Point Creating Locus Line Q>, <Point P>)

Returns the locus curve of the point Q, which depends on the point P.
Point P needs to be a point on an object (e. g. line, segment, circle). 
 Locus( <Point Creating Locus Line Q>, <Slider t>)

Returns the locus curve of the point Q, which depends on the values assumed by the slider t.
 Locus( <Slopefield>, <Point> )

Returns the locus curve which equates to the slopefield at the given point.
 Locus( <f(x, y)>, <Point> )

Returns the locus curve which equates to the solution of the differential equation \(\frac{dy}{dx}=f(x,y)\) in the given point. The solution is calculated numerically.
Loci are specific object types, and appear as auxiliary objects. Besides Locus command, they are the result of some Discrete Math Commands and SolveODE Command. Loci are paths and can be used within pathrelated commands such as Point. Their properties depend on how they were obtained, see e.g. Perimeter Command and First Command.
See also Locus tool. 
Warning
A locus is undefined when the dependent point is the result of a Point Command with two parameters, or a PathParameter Command.