The LawCurve section of tutorials covers the new LawCurve node type.
Watch this introductory video about the GenerativeComponents LawCurve: http://communities.bentley.com/products/products_generativecomponents/m/generative_components-files/272240/download
A law curve is a curve that follows some law, or rule, or function. Usually it is a curve with a defined start and end, so that it can be mapped onto other finite curves. An example is the Sine curve, which is theoretically infinite but for which it makes sense to define an interval, for example from 0 degrees to 360 degrees.
A law curve is most often used to generate a set of discrete values that have an overall smooth relationship as defined by the curve. This could be used for example to define the size of floor plates to create a gently curving silhouette for a building, or the curvature for a Gaudiesque roofline.
In the case of the Sine curve y = Sin(x) with x ϵ [0°, 360°]
...if it is sampled at independent variable x from 0° to 360° in steps of 30° yields
y = {0.0, 0.5, 0.866, 1.0, 0.866, 0.5, 0.0, -0.5, -0.866, -1.0, -0.866, -0.5, 0.0}
...as dependent variable.
The new LawCurve is placed by dragging and dropping the LawCurve icon into the Graph window.
After clicking on the curve preview on the node the larger curve control opens in which the vertical position of the control points can be interactively controlled to modify the curve.
The introductory LawCurve video describes the advantages of the current LawCurve implementation and what a control could look like that emulates the previous implementation of the LawCurve.
The other LawCurve Wiki entries describe