anchor.diff:  double precision :: look_x
   double precision :: look_y
   double precision :: look_z
  +
  +double precision :: zoom_scale
   
   end module
   
  
positive.code:     write(stderr,*)
  endif
  
  write(stderr,*) 'Usage: perspective -viewer vx,vy,vz -look lx,ly,lz [-f IFILE] [-o OFILE]'
  write(stderr,*)
  write(stderr,*) '-viewer vx,vy,vz       Viewer position'
  write(stderr,*) '-look lx,ly,lz         Look vector (from viewer to vanishing point)'
  write(stderr,*) '-f IFILE               Input file: x y z'
  write(stderr,*) '-o OFILE               Output file: projected x y'
  
  
negative.code:                             viewer_z, &
                              look_x, &
                              look_y, &
                              look_z, &
                              zoom_scale
  
  implicit none
  
  ! Local variables
  integer :: i, luin, luout, nline, ios
  character(len=512) :: input_line
  character(len=64) :: ch64
  double precision :: x, y, z, xproj, yproj
  logical :: isExtraData
  
  
  ! Parse command line
  