Smallest enclosing circle

This is an implementation of Welzl (1991) algorithm of smallest enclosing circle. Uses some parts of Mike Bostock's code for circumscribed discs.

Move points around and click to add new ones.

<!doctype html>
<html>
  <head>
    <title>Simple circle packing</title>
    <script src="https://unpkg.com/d3@4.4.1"></script>
    <style>

html, body {
      margin: 0;
      padding: 0;
      width: 100%;
      height: 100%;
    }

.control {
      position: absolute;
      top: 20px;
      right: 20px;
      padding: 10px 20px;
      font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
      font-weight: 300;
      font-size: 13px;
      background: #fff;
      border-radius: 4px;
      box-shadow: 0 0 5px rgba(0,0,0,0.5);
    }

.control h4 {
        font-weight: 300;
      }

.control input[type=number] {
        width: 50px;
      }

.circle {
      fill: black;
      fill-opacity: 0.5;
    }

.enclosing-circle {
      fill: none;
      stroke: red;
    }

text {
      fill: white;
      font-family: Monaco, 'Courier New', Courier, monospace;
    }

</style>
  </head>
  <body>
    <form class="control" id="form">
      <p>Drag points around to update.<br/> Click to add new points</p>
      <p><label><input type="number" min="0" name="numCircles" step="1" value="10"> circles</label></p>
      <p><label><input type="number" min="1" value="10" name="minR"> min R</label></p>
      <p><label><input type="number" min="1" value="100" name="maxR"> max R</label></p>
      <p><label><input type="checkbox" name="circles" checked> circles</label>
      <p>
        <button name="generate" type="reset">Generate</button>
      </p>
    </form>
    <script src="index.js"></script>
  </body>
</html>

https://unpkg.com/d3@4.4.1