Butterfly          { ; type sqr(1/cos)                      Pieter Branderhorst
                     ;  Version 2001 Patchlevel 11
  reset=2001 type=sqr(1/fn) function=cos
  corners=-3.5926327/-2.6917993/0.449396/1.125021 float=y maxiter=10
  decomp=256 colors=000<254>000
  }