math /xrange -2:2
margin 0.02
plot sin(3.141592*x)
top line
ticks bottom /minor -1.75,-1.25,-0.75,-0.25,0.25,0.75,1.25,1.75\
      /major -2,-1.5,-1,-0.5,0,0.5,1,1.5,2 \
      /labels='$-2\pi$,$-\frac{3\pi}{2}$,$-\pi$,$-\frac{\pi}{2}$,\
0,$\frac{\pi}{2}$,$\pi$,$\frac{3\pi}{2}$,$2\pi$'