anchor.diff:  		if((vortexKillX .and. abs(xloc) > vortexKillXDist) .or.&
   		   (vortexKillY .and. abs(yloc) > vortexKillYDist)) then
   			write(6,*) "Killing negative vortex at: ", xloc, ", ", yloc
  -			call insert_vortex(xloc,yloc,1.0d0)
  +			call insert_vortex(xloc,yloc,1)
   			call set_homg_sq(nint(xloc/DSPACE),nint(yloc/DSPACE),8)
   		end if
   	end do
  
positive.code: 		if((vortexKillX .and. abs(xloc) > vortexKillXDist) .or.&
  		   (vortexKillY .and. abs(yloc) > vortexKillYDist)) then
  			write(6,*) "Killing positive vortex at: ", xloc, ", ", yloc
  			call insert_vortex(xloc,yloc,-1.0d0)
  			call set_homg_sq(nint(xloc/DSPACE),nint(yloc/DSPACE),8)
  		end if
  	end do
  
negative.code: subroutine insert_vortex(xloc,yloc,circ)
  	use params
  	implicit none
  	integer :: i,j,k,circ
  	double precision :: xloc,yloc,rs,xx,yy
  	double precision, dimension(-NX/2:NX/2,-NY/2:NY/2) :: R
  
  	do i = -NX/2, NX/2
  		do j = -NY/2, NY/2
  			xx = (i*DSPACE)
  			yy = (j*DSPACE)
  			rs=(xx-xloc)**2.0d0 + (yy-yloc)**2.0d0;
  			IMPOSEDPHASE(i,j) = IMPOSEDPHASE(i,j)*exp(circ*EYE*(atan2(yy-yloc,xx-xloc)))
  			R(i,j) = sqrt(rs*(0.3437+0.0286*rs)/(1+0.3333*rs+0.0286*rs*rs)); 
  		end do
  	end do
  	GRID = sqrt(GRID*conjg(GRID))*R*IMPOSEDPHASE
  end subroutine
  
  subroutine velxy(phase,velx,vely)
  