Hi jweaver,
If you are using Free Subscription it seems like there is no direct way to do that. In some cases it is possible to substitute t (time) as the input variable (x) in the graph and use a corresponding ramp source in your circuit. It may then be acceptable to use Transient Analysis to generate the graph.
If you have a Premium account you can consider using the Expression Plotter.
Best regards,
G. Goodwin
