Today's post is another formula by Kerry Mitchell based on the Julia iteration loop.
Gif and jpg version available at http://maxitersfractalfollies.blogspot.com

Threaded Julia       { ; fract499.gif another Julia iteration loop fractal
                     ; blank
                     ; calctime   0:05:22.08
                     ; created Nov 04, 2010
                     ;  Fractint Version 2004 Patchlevel 10
  reset=2004 type=formula formulafile=kerrym.frm formulaname=km_08
  center-mag=-0.730914/0.135225/2.109705
  params=0.5243385113071077/0.07968382824182867/-0.8776207770012513/-0.809\
  0762047181616/-0.5746330149235511/0.3112582781456953/-0.8414868617816705\
  /0.2847071749015778 float=y maxiter=1500 inside=0 decomp=256
  periodicity=0
  colors=000734633523422312211101000000100200311411512612723823924A34B35B3\
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  pynpynqyoqyprypsyqsyrtyrtzsuztuztvzuvzvwzwwzwxzxxzyyzyyzzzzzzzyyzxxzxxzw\
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  _xQZxQZxPYxOYxOXxNXxMWxMWxLVxKUwJTvJTuJTtISsISrIRqIRpHQoHQnHPnGPmGOlGOkF\
  NjFNiFNhFMgEMfELeELdDKcDKbDJaCJ`CI_CIZCHYBHYBHXBGWAGVAFUAFTAES9ER9DQ9DP8\
  CO8CN8BM7BL7AK7AJ7AI69H69H68G58F57E57D46C46B45A45934834
  }
frm:km_08 { ; Kerry Mitchell 11may98
        ; originally conic-near_jul16
        ; tweaked by rjr 2k04 to allow user to directly input
        ; julia parameters previously hardcoded to 0.2882,0.0106
        cc=p4, zc=pixel, maxr=1e12, minr=maxr, iter=1
        a=real(p1), b=imag(p1), c=real(p2), d=imag(p2)
        e=real(p3), f=imag(p3):
        iter=iter+1, zc=sqr(zc)+cc, x=real(zc), y=imag(zc)
        conic=|x*(a*x+b)+y*(c*y+d)+e*x*y+f|
        if (conic<minr)
          minr=conic
          end if
        if ((|zc|>maxr)||(iter==maxit))
          iter=-1
          t=log(minr)
          z=cos(t)+flip(sin(t))
          end if
        iter>0
        }
Roger Alexander