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| Keywords: Triskele-Symbol-spiral-five-thirds-turns.png A spiral Triskelion symbol constructed from mathematical Archimedean spirals A less wound version of Image Triskele-Symbol-spiral png with one and two thirds turns in each spiral instead of two For a more elaborate spiral triskelion symbol with three turns see Image Triple-Spiral-Symbol-filled png and for the most elaborate version see Image Triple-Spiral-Symbol-4turns-filled png For a basic triple-spiral see Image Triple-Spiral-Symbol png and for wheeled forms of the spiral triskelion/triple spiral symbol see Image Wheeled-Triskelion-basic png Image Roissy triskelion iron ring signet png Image Triple-spiral-wheeled-simple png or Image Triskelion-spiral-threespoked-inspiral png For a spiral triskelion with a hollow triangle in the center see Image Triskele-hollow-triangle png For a partial tesselation of similar shapes see Image Triskele-quasi-tesselation svg Generated by means of the following PostScript code <pre> /archimdouble PostScript program to display an Archimedean spiral by approximating it with Bezier curves Can display a double spiral two spirals rotated by 180 degrees with respect to each other Parameters centerx horizontal coordinate of center of spiral centery vertical coordinate of center of spiral rotf degrees to rotate /sepwid 110 def width separating successive turnings of spiral half this if double spiral is selected /incrm 15 def insert a curve point after this number of degrees /sweeps 1 67 def number of 360 degree turnings to show /double 1 def change to 0 to display single spiral Procedures /pi 3 1415926535898 def/radians 57 295779513082 def /sepwid sepwid pi div 2 div def gsave centerx centery translate rotf rotate /aspiral /prevbezy 0 def 0 0 moveto 0 incrm sweeps 360 mul 7 dup repeat phase add cos/costh exch def phase add sin/sinth exch def costh mul radians div/thcosth exch def sinth mul radians div/thsinth exch def thcosth sepwid mul/x exch def thsinth sepwid mul/y exch def /slope sinth thcosth add costh thsinth sub div def sinth 0 gt sinth 0 eq costh -1 eq and or /flag -1 def /flag 1 def ifelse /A exch def A 49 29348 lt A 180 gt A 196 273450852 lt and A 360 gt A 368 8301 lt and A 540 gt A 545 9907 lt and A 720 gt A 724 5217 lt and A 900 gt A 903 6281968 lt and or or or or or /flag flag neg def if incrm sub 3 dup repeat phase add cos sepwid mul mul radians div /prevx exch def phase add sin sepwid mul mul radians div /prevy exch def incrm add 3 dup repeat phase add cos sepwid mul mul radians div /nextx exch def phase add sin sepwid mul mul radians div /nexty exch def /prevdist x prevx sub dup mul y prevy sub dup mul add sqrt pi div def /nextdist x nextx sub dup mul y nexty sub dup mul add sqrt pi div def /normaliz slope slope mul 1 add sqrt def 0 eq /prevbezx phase cos nextdist mul def prevbezx prevbezy x 1 flag mul normaliz div prevdist mul sub y slope flag mul normaliz div prevdist mul sub x y curveto /prevbezx x 1 flag mul normaliz div nextdist mul add def /prevbezy y slope flag mul normaliz div nextdist mul add def ifelse for stroke def /phase 0 def aspiral If different sweeps parameter for second spiral define here /sweeps 1 34 def double 0 ne /phase 180 def aspiral if grestore def gsave 792 -230 translate - 95 95 scale -4 rotate /centerx 304 def/centery 550 def/rotf 120 def archimdouble /centerx 634 def/centery 550 def/rotf 240 def archimdouble /centerx 469 def/centery 835 7884 def/rotf 0 def archimdouble grestore showpage EOF</pre> 2005 AnonMoos Triskele-Symbol-spiral-five-thirds-turns svg Triple spiral Archimedean spirals Images with PostScript source code | ||||
