PSTricks pst-bezier

••••••••••••••••3 The\psbcurvemacro 53211\begin{pspicture}[showgrid=true](5,3)2 \psbcurve(1,1)(2,2)(3,1)(4,2)3\end{pspicture}00 1 2 3 4 5As usual, options can be specified within brackets.3211\begin{pspicture}[showgrid=true](5,3)2 \psbcurve[showpoints=true](1,1)(2,2)(3,1)(4,2)3\end{pspicture}00 1 2 3 4 5As youcansee intheabove example, theshowpoints feature works(partially) with\psbcurve.The next figure shows again the curve from the first example. This time labels areadded to the points (this is just for the following description, it is not a feature of\psbcurve).3210#» p 0 = #» l 1#» r 1#» p 1#» l 2#» r 2#» p 2#» l 30 1 2 3 4 52 \psbcurve[showpoints=true](1,1)(2,2)(3,1)(4,2)3 \uput[-90](1,1){$\vec{p}_{0}=\vec{l1\begin{pspicture}[showgrid=true](5,3)#» r 3 = #» }_{1}$}p 34 \uput[90](1.5,2){$\vec{r}_{1}$}5 \uput[90](2,2){$\vec{p}_{1}$}6 \uput[90](2.5,2){$\vec{l}_{2}$}7 \uput[-90](2.5,1){$\vec{r}_{2}$}8 \uput[-90](3,1){$\vec{p}_{2}$}9 \uput[-90](3.5,1){$\vec{l}_{3}$}10 \uput[90](4,2){$\vec{r}_{3}=\vec{p}_{3}$}11\end{pspicture}The points labeled with #» p k (k = 0,... ,3) are the interpolation points, these oneslabelledwith #» l 1 ,... , #» l 3 ,andtheseoneslabelled with #» r 1 ,... , #» r 3 aretheleftandrightcontrol points, respectively.Betweeneachconsecutivepair #» p k−1 , #» p k ofinterpolationpointsthe\psbcurvemacrodraws a cubic Bezier spline. The control points #» l k and #» r k determine the tangentialdirection of the bezier spline at the interpolation points. More exactly, the bezierspline from #» p k−1 to #» p k is tangent to the vector #» l k − #» p k−1 at the point #» p k−1 andtantengial to the vektor #» r k − #» p k at the point #» p k .