title: Trouble with precision, point accuracy at intersection of 3 planes
body: <p>have tried multiple methods of plane intersection, the code is not producing an accurate result. At some angles its pretty good, for a right angle triangle, roughly in position but noticeably off.</p>
  <pre><code>xyzPoint return_Intersect_3planes(Tri tri1, Tri tri2, Tri tri3) {
  
  double x1 =  0.646;
  double y1 =  0.210;
  double z1 =  2.147;
  double a1 =  0.251;
  double b1 =  -0.456;
  double c1 = -0.411;
  double d1 = -((a1 * x1) + (b1 * y1) + (c1 * z1));
  
  double x2 = -0.0744;
  double y2 = 0.0808;
  double z2 = 2.082;
  double a2 = -0.1218;
  double b2 = -0.2606;
  double c2 = -0.748;
  double d2 = -((a2 * x2) + (b2 * y2) + (c2 * z2));
  
  double x3 = 0.10627;
  double y3 = 0.3924;
  double z3 = 2.335;
  double a3 = 0.0987;
  double b3 = 0.3236;
  double c3 = -0.278;
  double d3 = -((a3 * x3) + (b3 * y3) + (c3 * z3));
  
  
  double D =  (a2 * b2 * c3) + (b1 * c2 * a3) + (c1 * a2 * b3) - (a3 * b2 * c1) - (b3 * c2 * a1) - (c3 * a2 * b1);
  double Dx = (d1 * b2 * c3) + (b1 * c2 * d3) + (c1 * d2 * b3) - (d3 * b2 * c1) - (b3 * c2 * d1) - (c3 * d2 * b1);
  double Dy = (a1 * d2 * c3) + (d1 * c2 * a3) + (c1 * a2 * d3) - (a3 * d2 * c1) - (d3 * c2 * a1) - (c3 * a2 * d1);
  double Dz = (a1 * b2 * d3) + (b1 * d2 * a3) + (d1 * a2 * b3) - (a3 * b2 * d1) - (b3 * d2 * a1) - (d3 * a2 * b1);
  
  
  
  xyzPoint Intersection;
  Intersection.x = Dx / D;
  Intersection.y = Dy / D;
  Intersection.z = Dz / D;
  
  
  return Intersection;
  </code></pre>
  <p>}</p>
  <p><a href="https://i.stack.imgur.com/wNadQ.png" rel="nofollow noreferrer">The input numbers</a></p>
  <p>Result is</p>
  <p>x = 0.00276579 y = -0.32880155 z = -4.0193058
  (this has been flipped to negative and might be totally wrong?)</p>
  <p>Correct position based on CAD is</p>
  <p>x = -0.002 y = 0.204 z = 2.498</p>
  <p>ODS (open office calc) file has been uploaded
  <a href="https://filebin.net/g6onuah7q5rfg7lj" rel="nofollow noreferrer">https://filebin.net/g6onuah7q5rfg7lj</a></p>