Today's post is another fractal with a thread like structure. Maybe I should start a thread on threads.
Again I posted a before and after pair of graphics on my blog. With resampling the visibility of
thread like form is significantly enhanced. If you want to see threads that don't say tailor
go to http://maxitersfractalfollies.blogspot.com for a gander.
fract281.gif { ; before anti-aliasing
; blank
; calctime 0:03:43.78
; created Jun 29, 2010
; Fractint Version 2004 Patchlevel 9
reset=2004 type=formula formulafile=_f.frm formulaname=field4_man
center-mag=-0.29661890258823510/-0.65850594286477460/81.3497
params=1000000/8 float=y maxiter=1500 inside=0 proximity=1
outside=fmod decomp=256 periodicity=0
colors=05F05F05F16G16G16G16G16G27H27H27H27H27H38I38I38I38I38I49J49J49J49\
J49J5AK5AK5AK5AK5AK6BL6BL6BL6BL7CM7CM7CM7CM7CM8DN8DN8DN8DN8DN9EO9EO9EO9E\
O9EOAFPAFPAFPAFPAFPBGQBGQBGQBGQBGQCHRCHRCHRCHRCHRDISDISDISDISDISEISEJTFJ\
TFKTGKUGLUHLVHMVIMVINWJNWJOWKOXKPXLPYLQYMQYMRZNRZNSZOS_OT_PT_PT`QU`QUaRV\
aRVaSWbSWbTXbTXcUYcUYcVZdVZdW_eW_eX`eX`fYafYafZbgZbg_ch_ch`ch`diadiaeibe\
jbfjcfjcgkdgkdhlehleilfimfjmgjmgknhknhlniloimojmpjmpknpknqloqloqmprmprnq\
snqsorsortpstpstqtuqturuuruvsvvsvwtwwtwwuxxuxxuxxvyyvyywzzvyyvyyuxxtxxtw\
wsvwsvvruvquuqtupstostorsnqsnqrmprlpqloqknpjnpjmoimohlnhkngkmgjmfjleileh\
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OBFOAFN9EN9EM8DM8CL7CL6BK6AK5AJ49J49I38I37H27H16G16G05F
}
frm:field4_man { ; Kerry Mitchell 20jan98
;
; Colors Mandelbrot set by nearest approach to
; period 4 field lines
;
; use decomp=256
; real(p1) = bailout (try 1e12)
; imag(p1) = number of field line to use: 0 - 15
; 4 iterations per pixel
; variable zc used for calculation, z for coloring
;
zc=0, c=pixel, maxr=real(p1), minr=maxr, iter=1
fieldangle=tan(imag(p1)*2*pi/15):
;
; iteration
; compare tangent of polar angle with desired
; field line angle, update minimum if needed
;
iter=iter+4, zc=sqr(zc)+c, zc=sqr(zc)+c, zc=sqr(zc)+c
zc=sqr(zc)+c, rzc=|zc|, tanangle=imag(zc)/real(zc),
r=cabs(fieldangle-tanangle)
if (r<minr)
minr=r
end if
;
; bailout
; set "iteration done" flag (iter=-1)
; use log of minimum difference of angles as
; decomposition angle
;
if ((rzc>maxr)||(iter>=maxit))
iter=-1
angle=log(minr)
z=cos(angle)+flip(sin(angle))
end if
iter>0
}
Roger Alexander
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