# plotting a rainbow 

n<-16
colors<-rev(rainbow(n=16))

# To form a half-circle ('rainbow-shaped') I use cosine and sine functions
# each time the radius gets increased a little bit by the scaling
# factor, and every time a different color is picked from the 
# color-values (RBG-code: FF0000 would be pure red, 00FF00, green, 00000FF blue
# these are hexadecimal numbers). rainbow
# 
r<-seq(-pi/2,pi/2,0.1)
y<-cos(r)
x<-sin(r)

scale<-1
incr<-0.2
linewidth<-2

plot(c(-2,2),c(-2,2),typ='n',axes=FALSE,xlab='',ylab='',main="A rainbow color demo")
for (i in 1:n){
	scale<-scale+incr/n
	print(scale)
  lines((scale*x),(scale*y),col=colors[i],typ='l',lwd=linewidth)
  
}