I need to calculate the error resulting from approximating a parametric cubic Bezier curve using a quadratic B-spline.
For approximating the cubic Bezier we're using a quadratic B-spline with a control polygon made of the two anchor points of the cubic Bezier and the control points of the quadratic bezier curves that we are obtained when the DeCasteljou's subdivision algorithm is used two divide the cubic Bezier curve in t=0.5.
This technique was extracted from page 83 of the pdf found at:

