Function d3_geo_lengthLineStart

explainshell/web/static/js/d3.v3.js:3223–3237

()

    polygonEnd: d3_noop
  };
  function d3_geo_lengthLineStart() {
    var λ0, sinφ0, cosφ0;
    d3_geo_length.point = function(λ, φ) {
      λ0 = λ * d3_radians, sinφ0 = Math.sin(φ *= d3_radians), cosφ0 = Math.cos(φ);
      d3_geo_length.point = nextPoint;
    };
    d3_geo_length.lineEnd = function() {
      d3_geo_length.point = d3_geo_length.lineEnd = d3_noop;
    };
    function nextPoint(λ, φ) {
      var sinφ = Math.sin(φ *= d3_radians), cosφ = Math.cos(φ), t = Math.abs((λ *= d3_radians) - λ0), cosΔλ = Math.cos(t);
      d3_geo_lengthSum += Math.atan2(Math.sqrt((t = cosφ * Math.sin(t)) * t + (t = cosφ0 * sinφ - sinφ0 * cosφ * cosΔλ) * t), sinφ0 * sinφ + cosφ0 * cosφ * cosΔλ);
      λ0 = λ, sinφ0 = sinφ, cosφ0 = cosφ;
    }
  }
  function d3_geo_conic(projectAt) {
    var φ0 = 0, φ1 = π / 3, m = d3_geo_projectionMutator(projectAt), p = m(φ0, φ1);
    p.parallels = function(_) {