INCLAN Graphics: plot curve

Synopsis

plot curve x₁ y₁ x₂ y₂ x₃ y₃ x₄ y₄ ... (normal mode)

plot curve [[x] y₁...](list mode)

Description

Normal mode:
The command draws a Bézier spline curve defined by the points ('x_i,y_i). The total number of points must be 3n + 1, with integer n ≥ 1. The resulting curve passes through the points 1, 4, 7,...; the other points guide the curve. Four points define the shape of each segment of the curve: The curve segment leaves (x₁,y₁) along the direction of the straight line connecting (x₁,y₁) with (x₂,y₂) and reaches (x₄,y₄) along the direction of the straight line connecting (x₃,y₃) with (x4,y4). The lengths of the lines connecting (x₁,y₁) with (x₂,y₂) and (x₃,y₃) with (x₄,y₄) represent, in a sense, the “velocity” of the path at the endpoints. The curve segment is always enclosed by the convex quadrilateral defined by the four points.

List mode:
The command draws Bézier spline curves through the points of the given vector expressions x, y₁,... If no vector expressions are specified, splines are drawn through the points of all list columns. If the x-expression is omitted (i.e. if only a single expression, y₁, is given), the x-coordinates are taken from the x-column of the list. The number of list points must be 3n + 1, with integer n.