The folder *:Maple V Release 4:Math 222:Lecture 5* contains
small movies of the *flows* associated to the four
vector fields given below. (The *flow of a vector field* on a set
at time *t* gives a new set representing where at time *t* the points
of the old set would be if each followed a flowline for time *t*.)

The four examples there are

**Nonzero Divergence and Zero Curl:**-
*v*(*x*,*y*)=<5*x*+10*y*,10*x*+5*y*>. **Zero Divergence and Zero Curl:**-
*v*(*x*,*y*)=<5*x*+10*y*,10*x*-5*y*>. **Zero Divergence and Nonzero Curl:**-
*v*(*x*,*y*)=<10*y*,-10*x*>. **Nonzero Divergence and Zero Curl:**-
*v*(*x*,*y*)=<5*x*+15*y*,-10*x*+5*y*>.