1. A computer-implemented method, comprising: displaying a graph on a display device, the graph including a parametric curve; receiving through a user interface device user input identifying a parameter for the parametric curve, wherein the parametric curve is dependent upon a value of the parameter; using a data processor to identify a range of values for the parameter, wherein the range of values is identified independent of the user input identifying the parameter; using a data processor to determine a range of curves for the parametric curve based on the identified range of values for the parameter, the range of curves representing all curves resulting from values of the parameter within the identified range of values for the parameter; and updating the graph displayed on the display device to include within the graph a highlighted area corresponding to the range of curves for the parameter, the highlighted area including a visual indication having a visually distinct appearance relative to areas outside the highlighted area in the graph.