site/inversion/index.html

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<title>Yantra Inversion</title>
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<canvas id="c"></canvas>
<header><a class="home" href="/">← maths</a><h1>Śrī Yantra <i>inverted</i></h1><div class="sub">z ↦ z / |z|² in the outer circle · drag to pan · pinch or scroll to zoom</div></header>
<div class="tray"><div class="inner">
  <div class="seg" role="group" aria-label="Show">
    <button id="s-orig" aria-pressed="false">original</button>
    <button id="s-inv" aria-pressed="false">inverted</button>
    <button id="s-both" aria-pressed="true">both</button>
  </div>
  <label class="sl" for="zoom">zoom <input id="zoom" type="range" min="-1.2" max="1.6" step="0.01" value="-0.5"> <span class="val" id="zv"></span></label>
  <div class="note" id="note"></div>
</div></div>
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function seg(a,b,n=400){const o=[];for(let i=0;i<=n;i++){const t=i/n;o.push([a[0]+(b[0]-a[0])*t,a[1]+(b[1]-a[1])*t])}return o}
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const inv=([x,y])=>{const r=x*x+y*y;return r<1e-12?null:[x/r,y/r]};
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function draw(){
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  document.getElementById('zv').textContent=zoom<1?zoom.toFixed(2)+'×':zoom.toFixed(1)+'×';
  document.getElementById('note').textContent=show==='orig'
   ?'The flat yantra inside the circle of inversion.'
   :'Every straight side becomes a circle arc through the bindu. The small inner triangles map far outside; the outer triangles fold just beyond the ring, and the bindu itself goes to ∞.';
}
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