The Pickover attractor or Clifford Attractor (named after Clifford A. Pickover) is the system of equations:

`x`_{n+1} = sin(`a` `y`_{n}) + `c` × cos(`a` `x`_{n})

`y`_{n+1} = sin(`b` `x`_{n}) + `d` × cos(`b` `y`_{n})

Any given set of values for the parameters `a`, `b`, `c`
and `d` defines one specific attractor.
They are attractors
because the system will evolve to the same pattern for any starting point (x_{0} , y_{0}).

This JavaScript application plots a number of attractors with various sets of parameters and also uses some variations of the above given system of equations. Try changing the color during the animation for a nice effect.