Image:Triskele-Symbol-spiral-five-thirds-turns.svg

[edit] Summary

A spiral Triskelion symbol, constructed from mathematical Archimedean spirals. A less wound version of Image:Triskele-Symbol-spiral.svg , 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.svg, and for the most elaborate version, see Image:Triple-Spiral-Symbol-4turns-filled.svg. For a basic triple-spiral, see Image:Triple-Spiral-Symbol.svg, and for "wheeled" forms of the spiral triskelion/triple spiral symbol, see Image:Wheeled-Triskelion-basic.svg , Image:Roissy triskelion iron ring signet.png , or Image:Triskelion-spiral-threespoked-inspiral.svg . For a spiral triskelion with a hollow triangle in the center, see Image:Triskele-hollow-triangle.svg .

For a partial tesselation of similar shapes, see Image:Triskele-quasi-tesselation.svg .

SVG version of Image:Triskele-Symbol-spiral-five-thirds-turns.png .

Converted from the following PostScript code:

%!
/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

[edit] Licensing

I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide. In case this is not legally possible: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law. Afrikaans | Alemannisch | Aragonés | العربية | Asturianu | Български | Català | Česky | Cymraeg | Dansk | Deutsch | Eʋegbe | Ελληνικά | English | Español | Esperanto | Euskara | Estremeñu | فارسی | Français | Galego | 한국어 | हिन्दी | Hrvatski | Ido | Bahasa Indonesia | Íslenska | Italiano | עברית | Kurdî / كوردی | Latina | Lietuvių | Latviešu | Magyar | Македонски | Bahasa Melayu | Nederlands | ‪Norsk (bokmål)‬ | ‪Norsk (nynorsk)‬ | 日本語 | Polski | Português | Ripoarisch | Română | Русский | Shqip | Slovenčina | Slovenščina | Српски / Srpski | Svenska | ไทย | Tagalog | Türkçe | Українська | Tiếng Việt | Walon | ‪中文(简体)‬ | ‪中文(繁體)‬ | zh-yue-hant | +/-

• Triple spiral
• User:Jim.belk/Dihedral Group Draft