Function: plotpoints
Section: graphic
C-Name: plotpoints
Prototype: vLGG
Help: plotpoints(w,X,Y): draws in rectwindow w the points whose x
 (resp y) coordinates are in X (resp Y). If X and Y are both
 single values (i.e not vectors), draw the corresponding point (and move
 cursor).
Doc: draw on the rectwindow $w$ the
 points whose $(x,y)$-coordinates are in the vectors of equal length $X$ and
 $Y$ and which are inside $w$. The virtual cursor does \emph{not} move. This
 is basically the same function as \kbd{plothraw}, but either with no scaling
 factor or with a scale chosen using the function \kbd{plotscale}.

 As was the case with the \kbd{plotlines} function, $X$ and $Y$ are allowed to
 be (simultaneously) scalar. In this case, draw the single point $(X,Y)$ on
 the rectwindow $w$ (if it is actually inside $w$), and in any case
 \emph{move} the virtual cursor to position $(x,y)$.

 If you draw few points in the rectwindow, they will be hard to see; in
 this case, you can use filled boxes instead. Compare:
 \bprog
 ? plotinit(0, 100,100); plotpoints(0, 50,50);
 ? plotdraw(0)
 ? plotinit(1, 100,100); plotmove(1,48,48); plotrbox(1, 4,4, 1);
 ? plotdraw(1)
 @eprog
