x=linspace(-360,360)
  a=sin((pi/180)*3*(x-90))
subplot(3,1,1)
plot(x,a)
grid("on")
subplot(3,1,2)
  b=cos((pi/180)*.5*(x+45))
plot(x,b)
grid("on")
subplot(3,1,3)
  c=-1*sin((pi/180)*(x-60)/3)-2
plot(x,c)
grid("on")
print ("plot3.pdf", "-dpdf")
