x1' = w + a12 *sin(x2-x1) + a13 *sin(x3-x1) + a14 *sin(x4-x1)
  x2' = w + a21 *sin(x1-x2) + a23 *sin(x3-x2) + a24 *sin(x4-x2)
 x3' = w + a32 *sin(x2-x3) + a31 *sin(x1-x3) + a34 *sin(x4-x3)
 x4' = w + a42 *sin(x2-x4) + a43 *sin(x3-x4) + a41*sin(x1-x4)
par a12=-1,a21=-1,a23=-1,a32=-1,a34=-1,a43=-1,a14=-1,a41=-1
par a13=0,a31=0,a24=0,a42=0
par w=1
init x1=1,x2=3,x3=4.5,x4=6
done