Draws a circle on an existing plot.

```
draw.circle(x,y,radius,nv=100,border=NULL,col=NA,lty=1,density=NULL,
angle=45,lwd=1)
```

x,y

Coordinates of the center of the circle.

radius

Radius (or radii) of the circle(s) in user units.

nv

Number of vertices to draw the circle.

border

Color to use for drawing the circumference.

col

Color to use for filling the circle.

lty

Line type for the circumference.

density

Density for patterned fill. See `polygon`.

angle

Angle of patterned fill. See `polygon`.

lwd

Line width for the circumference.

A list with the x and y coordinates of the points on the circumference of the last circle displayed.

`draw.circle` uses the dimensions of the plot and the `x` and
`y` coordinates to draw a circle rather than an ellipse.

# NOT RUN { plot(1:5,seq(1,10,length=5),type="n",xlab="",ylab="",main="Test draw.circle") draw.circle(2,4,c(1,0.66,0.33),border="purple", col=c("#ff00ff","#ff77ff","#ffccff"),lty=1,lwd=1) draw.circle(2.5,8,0.6,border="red",lty=3,lwd=3) draw.circle(4,3,0.7,border="green",col="yellow",lty=1, density=5,angle=30,lwd=10) draw.circle(3.5,8,0.8,border="blue",lty=2,lwd=2) # }