New in Wolfram Mathematica 7: Comprehensive Spline Support  previous | next 
Use Sophisticated Knot Control in B-Spline Curves
B-spline curves in Mathematica 7 support all possible combinations of knot configurations.
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Click for copyable input
SeedRandom[111]; pts = {{0, 0}, {1, 1}, {2, -1}, {3, 0}, {4, -2}, {5, 

   1}};

GraphicsGrid[

 Partition[

  Table[With[{knots = Sort[RandomInteger[10, 10]]}, 

    Graphics[{Green, Line[pts], Red, Point[pts], Thick, Black, 

      BSplineCurve[pts, SplineKnots -> knots]}, 

     PlotRange -> {{0, 5}, {-2, 2}}, PlotRangePadding -> Scaled[.04], 

     PlotLabel -> Style[knots, 9]]], {9}], 3], Frame -> All, 

 ImageSize -> {500, 500}]
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