Can one specify a custom force function for a force-directed layout?

I want to experiment with an alternative family force functions for force-directed graph layouts.

For each node n_i, I can define a "force function" f_i such that

• f_i ( n_i ) is identically zero; and
• f_i ( n_j ), where n_i != n_j, is the force on node n_i that is due to some other node n_j.

The net force on node n_i should then be the vector sum of the forces f_i ( n_j ), where n_j ranges over all other nodes¹.

Is there some way to tell d3.js to use these custom force functions in the layout algorithm?

[The documentation for d3.js's force-directed layout describes various ways in which its built-in force function can be tweaked, but I have not been able to find a way to specify an entirely different force function altogether, i.e. a force function that cannot be achieved by tweaking the parameters of the built-in force function.]

^{1IOW, no other/additional forces should act on node n_i besides those computed from its force function f_i.}

To achieve this, you'll need to create your own custom layout. There's no tutorial for this that I'm aware of, but the source code for the existing force layout should be a good starting point as, by the sound of it, the structure of your custom layout would be very similar to that.