anchor.diff:  end subroutine itransform
   
   !Radially grooved grating diffraction
  -!Assumes grating in x y plane, with grooves converging at 
  -!hubdist in positive y direction
  +!Assumes grating in x y plane, with hub at origin
   subroutine radgrat(x,y,l,m,n,wave,num,dpermm,order)
     !Declarations
     integer, intent(in) :: num
  
positive.code:     !Compute local d spacing in nm
      d = dpermm * sqrt(y(i)**2 + x(i)**2)
      !Compute local yaw
      !yaw = pi/2 - atan(-x(i)/abs(y(i)))
      !print *, yaw
      yaw = -pi/2 - atan2(x(i),y(i))
      !print *, yaw
      !read *, dum
  
negative.code: 
  end subroutine radgrat
  
  !Radially grooved grating diffraction with wavelength vector
  !Assumes grating in x y plane, with hub at origin
  subroutine radgratW(x,y,l,m,n,wave,num,dpermm,order)
    !Declarations
    integer, intent(in) :: num
  