Now that the backbone of the chart is done we're ready to create the links between the nodes. And here comes the interesting part. A warning however, the next steps require some heavy use of mathematics—Bézier curves.
According to Microsoft, by definition: "a Bézier spline is a curve specified by four points: two end points (p0 and p3) and two control points (p1 and p2). The curve begins at p0 and ends at p3. The curve doesn't pass through the control points, but the control points act as magnets, pulling the curve in certain directions and influencing the way the curve bends."
The following illustration shows a cubic Bézier curve along with its endpoints, control points and the equations to generate the curves: