Number (default: 300)
The number of times that all the forces in the diagram are being calculated and balanced. The default is set at 300, which should be enough for diagrams up to a hundred nodes. By increasing this parameter you increase the correctness of the simulation but it does not always lead to a more stable topology. In some situations a diagram simply does not have a stable minimum energy state and oscillates (globally or locally) between the minima. In such a situation increasing the iterations will not result in a better topology.
In situations where there is enough symmetry in the diagram the increased number of iterations does lead to a better layout. In the example below the 100 iterations was not enough to bring the grid to a stable state while 300 iterations did bring all the nodes in such a position that the (virtual) energy of the diagram is a minimum.
This setting is specific to the force-directed layout