A spiral with spirals. When I say fractal I say self-similarity. Fractint compatible gif
and re-sampled jpg at http://maxitersfractalfollies.blogspot.com.
fract420.gif { ; spirals
; blank
; calctime 0:09:55.07
; created Sep 16, 2010
; Fractint Version 2004 Patchlevel 9
reset=2004 type=formula formulafile=kerrym.frm
formulaname=bubbleboth_jul center-mag=0.135169/0.511853/13.33333
params=0.375/0.375/64/0.5/1/1 float=y maxiter=3600 inside=0
outside=atan periodicity=0
colors=05FOT_PT_PT`QU`QUaRVaRVaSWbSWbTXbTXcUYcUYcVZdVZdW_eW_eX`eX`fYafYa\
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}
frm:bubbleboth_jul { ; copy
; Kerry Mitchell
; color Julia sets with small bubbles
; filled with swirls (combination of rays and circles)
;
; use outside=iter, decomp=256
; p1 = Julia parameter
; real(p2) = bailout (at least 4)
; imag(p2) = radius of bubble (try ~ .1)
; real(p3) = amount of circles (0 for only rays, try 0.5)
; imag(p3) = amount of rays (0 for only circles, try 0.5)
; zc is the variable used for iteration, z for coloring
;
zc=pixel, c=p1, maxr=real(p2), minr=imag(p2), scale=2*pi/minr
minset=0, iter=1, rzc=cabs(zc), minzc=zc
weight=real(p3)+imag(p3)
weightc=real(p3)/weight, weightr=imag(p3)/weight
;
; initial check: see if pixel magnitude falls within threshold
; if so, set minset flag, update minimum to current magnitude
;
if (rzc<minr)
minr=rzc, minzc=zc, minset=1
end if
:
iter=iter+1, zc=sqr(zc)+c, rzc=cabs(zc)
;
; iteration check: see if iterate falls within threshold
; if so, set minset flag, update minimum to current magnitude
;
if (rzc<minr)
minr=rzc, minzc=zc, minset=1
end if
;
; bailout
; set "iteration done" flag (iter=-1)
; scale minr to find decomp angle for circles
; take polar angle from minzc to ray decomp angle
; final angle is weighted average of ray and circle angles
; if a new minimum was never set (minset=0),
; set z=0 (color 0 under decomp)
;
if ((rzc>maxr)||(iter==maxit))
iter=-1
anglec=scale*minr, angler=imag(log(minzc))
angle=weightc*anglec+weightr*angler
z=(cos(angle)+flip(sin(angle)))*minset
end if
iter > 0
}
Roger Alexander