Graphics, Figures & Tables ⇒ PSTricks: question about listplot plotstyle=curve

[aquamarijn]

PSTricks listplot draws a smooth curve through the points in a given list when I use the option plotstyle=curve. I have two questions.

1. How is the curve between two adjacent points determined mathematically? It doesn't seem to be a cubic spline (as would result from plotstyle=cspline). If it's a bezier curve, how is it determined (e.g. which intermediate control points)?
2. Is it possible to show or calculate the coordinates of a specific point in between two adjacent points from the list? Example: suppose the list is 0 0 3 1 5 7, how do I get the y-value of the listplot-curve at x=2?