# How to plot error curve between Bézier curve and a circle?

I have 2 curves on 1 axes. I've been working on how to plot the error between those 2 curves. I want to plot a new error curve on a new axes but I couldn't find the solution for this problem.

Here attached the sample Bézier curve and the circle. If you noticed the red dashed line is the error between those curves. So, I want to plot an error curve based on the differences of this 2 curves.

Cubic1 = {{-1, 0}, {-1, 1.5}, {0, 1.5}, {1, 1.5}, {1,0}};
Print[MatrixForm[Cubic1]]
C1 = Graphics[BezierCurve[Cubic1]];
c = BezierFunction[Cubic1]
pts1 = c /@ Range[1/5, 4/5, 1/5];
pts2 = {Cos[#], Sin[#]} & /@ (Pi Range[4/5, 1/5, -1/5]);
Show[Graphics[{Red, Point[Cubic1], Green, Line[Cubic1]},
Axes -> True], ParametricPlot[c[t], {t, 0, 1}],
ParametricPlot[{{ Cos[t], Sin[t]}}, {t, 0, Pi},
PlotLegends -> "Expressions", PlotStyle -> Orange],
Epilog -> {AbsolutePointSize, Red, Point[pts1], Point[pts2],
Dashed, Line /@ Transpose[{pts1, pts2}]}] I suppose you want the norm of the error, as a function of the parameter as opposed to the distance to the semicircle from a point on the Bézier curve.

Cubic1 = {{-1, 0}, {-1, 1.5}, {0, 1.5}, {1, 1.5}, {1, 0}};
c = BezierFunction[Cubic1];
circleFN = {Cos[Pi (1 - #)], Sin[Pi (1 - #)]} &;

Plot[Norm[c[t] - circleFN[t]], {t, 0, 1}] If you want the actual (vector) error, then do as follows:

ParametricPlot[c[t] - circleFN[t], {t, 0, 1}, AspectRatio -> 0.6] • Yeah!! This is what I want. Thank you so much. – BayWilson Sep 29 '16 at 3:39