anchor.diff:  	! Get ST-PCs
   	! ==========
   	if(present(stpc))then
  -!!$		if(not(allocated(stpc))) allocate(stpc(nt-nwindow+1, nkeep))
   		allocate(trff(nt, nchan))
   		trff = transpose(zff)
   		do im = 1, nkeep
  
positive.code: 
  	! External
  	! --------
  	real,   intent(in)									:: ff(:,:)
  	integer,intent(in)									:: nwindow, nkeep
  	real,	  intent(out), optional	:: steof(size(ff,1)*nwindow, nkeep), stpc(size(ff,2)-nwindow+1, nkeep), ev(nkeep)
  
  	! Internal
  	! --------
  	real, allocatable :: cov(:,:), eig(:), trff(:,:), zff(:,:), zsteof(:,:)
  	real :: wsteof
  	integer :: nchan, nsteof, nt
  	integer :: iw, iw1, iw2, i1, i2, im, ic1, ic2
  
  
  
negative.code: 		! Eigenvalues
  		! -----------
  		if(present(ev))then
  			ev = eig(nt:nt-nkeep+1:-1)
  		end if
  
  