Making a Shoot ‘Em Up Game: Carrot Invader - Learn GameSalad for iOS: Game Development for iPhone, iPad, and HTML5 - page 140

Basically, that's it. A parametric equation defines the X and Y based on a t
parameter. In GameSalad, you will define complex movement by constraining
the position.X and position.Y attributes to a formula based on the t parameter
where t is the Time attribute of the actor.
The next step is to develop your Google search skills to find a parametric
equation describing the complex movement you want to implement.
NOTE: The Time attribute is the internal clock of every implementation
of an actor on the scene. The clock will start from the moment the
actor appears on the scene or at the same time the scene is displayed
if the actor is initially on the screen. It is sensitive up to five digits after
the second. It will increase itself continuously with time.
Let's put into practice what you just learned.
Creating Movement with Parametric Equations
A quick search on Google gave me the following parametric equation for a heart
shape:
 X=sin 3 (t)
 Y=cos(t)-sin 4 (t)
The graph of this equation is shown in Figure 5-17.