 nominal length of the spring
(<a href="ForceDirectedLayout.html#springStiffness" class="tsd-kind-method">springStiffness</a>, <a href="ForceDirectedLayout.html#springLength" class="tsd-kind-method">springLength</a>) divided by the distance between the vertexes.
When the distance is less than the nominal length, the force pushes the vertexes apart; when the distance is greater, the force pulls them together.
You can easily assign the spring length and stiffness for all edges by assigning <a href="ForceDirec