anchor.diff:          xmid = 0.5*(xmax + xmin), xrange = xmax - xmin,                    &
           ymin=0., ymax=1.0, ymid = 0.5*(ymax + ymin), yrange = ymax - ymin, &
           zmin=0., zmax=1.0, zmid = 0.5*(zmax + zmin), zrange = zmax - zmin
  -   real(PLFLT) :: x_inclination, y_inclination, z_inclination,             &
  -        x_shear, y_shear, z_shear,                                         &
  +        real(PLFLT) :: y_location, z_location, &
  +        x_inclination, y_inclination, z_inclination,       &
  +        x_shear, y_shear, z_shear,                         &
           omega, sin_omega, cos_omega, domega
      integer     :: i, j
      real(PLFLT) :: radius, pitch, xpos, ypos, zpos
  
positive.code:       cos_omega = cos(omega)
        x_shear = 0.5*xrange*sin_omega
        z_shear = 0.5*zrange*cos_omega
        call plptex3( &
           xmid, ymax, zmax -(zmax-0.2)*(dble(i-1)/dble(NSHEAR-1)), &
           x_inclination, y_inclination, z_inclination, &
           x_shear, y_shear, z_shear, &
           0.5_plflt, "shear for y = y#dmax#u")
  
negative.code:       cos_omega = cos(omega)
        y_shear = -0.5*yrange*sin_omega
        z_shear = 0.5*zrange*cos_omega
        z_location = zmax -(zmax-0.2)*((i-1)/dble(NSHEAR-1))
        call plptex3( &
           xmax, ymid, z_location, &
           x_inclination, y_inclination, z_inclination, &
           x_shear, y_shear, z_shear, &
           0.5_plflt, "shear for x = x#dmax#u")
  