ldY" class="tsd-kind-method">gravitationalFieldY</a>).
You can easily assign the gravitational mass for all vertexes by assigning <a href="ForceDirectedLayout.html#defaultGravitationalMass" class="tsd-kind-accessor">defaultGravitationalMass</a>.
By default there is no gravitational field.</p>
<p>The spring forces on a vertex are only exerted by the edges connecting it with other vertexes.
The force along an edge is the stiffness of the spring times the difference of the distance between the vertexes and the