The Curl(F) calling sequence computes the curl of the vector field F in R^3.  This is equivalent to  and CrossProduct(Del, F).

If F is a Vector-valued procedure, the default coordinate system is used, and it must be indexed by the coordinate names.  Otherwise, F must be a vector field.

If F is a procedure, the result is a procedure.  Otherwise, the result is a vector field.

The Curl(c) calling sequence returns the differential form of the curl operator in the coordinate system specified by c, which can be given as:

* an indexed name, e.g.,

* a name, e.g., spherical; default coordinate names will be used

* a list of names, e.g., ; the current coordinate system will be used, with these as the coordinate names

The Curl() calling sequence returns the differential form of the curl operator in the current coordinate system.  For more information, see SetCoordinates.