Just one of many ways to describe parametric cubic polynomials. Other methods have different properties and do not always produce curves which go through control points.
Endpoint tangent vectors are specified by control points which are not on curve.
Interactive--user moves control points, polygon redraws. For this reason used in many drawing packages, and for describing font outlines.
The starting and ending tangent vectors below are P1P2 and P3P4.
Note: curve lies inside of convex hull of control points (shape you would get by stretching a rubber band around all points).
Animation - 10 MAY 95
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