public double vel(double v) {
            //  (((mD * u) + mC) * u + mB) * u + mA
            //  =  "mA + u*mB + u*u*mC+u*u*u*mD" a cubic expression
            // diff with respect to u = mB + u*mC/2+ u*u*mD/3
            // made efficent  (mD*u/3+mC/2)*u+mB;

            return (mD * THIRD * v + mC * HALF) * v + mB;
        }
Spline in N dimensions

@param points [mPoints][dimensionality]
ConstraintLayoutExamples/CycleEditor/src/com/google/androidstudio/motionlayoutcycles/HyperSpline.java