subroutine rotate
c---rotate particle cordinates around axis
c---------------------------------------------------------------------------
c
      include 'param_sz.h'
      include 'pcordcom.h'
      include 'syscom.h'
      include 'ucom.h'
c
c--------------------------------------------------------------------------
c*
      ne=rne
      ang=el(4,ne)
      r=sqrt(x**2+y**2)
      rbg=sqrt(bgx**2+bgy**2)
      phi=atan2(y,x)-ang
      bgphi=atan2(bgy,bgx)-ang
      x=r*cos(phi)
      y=r*sin(phi)
      bgx=rbg*cos(bgphi)
      bgy=rbg*sin(bgphi)
      return
      end
c++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*