pro calc_svd,m1,m2,n,d1,d2,u,v,l0,var,c1,c2

	  a=d1#transpose(d2)/(n+0.0)
	  svdc,a,l0,u,v
	  var=l0/total(l0)
	  c1=v#d1
	  c2=u#d2

	end




	file="skt.mon.mean.nc"
	file_id=ncdf_open(file)
	file_info=ncdf_inquire(file_id)
     	nvars=file_info.nvars      
     	print, "No. of variables", nvars
     	for var_id=0,nvars-1 do begin
          varinfo=ncdf_varinq(file_id, var_id)
          print, var_id, "  ", varinfo.name        
     	endfor

	var_id=3
	ncdf_attget, file_id, var_id, "missing_value", missing_value
	ncdf_attget, file_id, var_id, "scale_factor", scale_factor
	ncdf_attget, file_id, var_id, "add_offset", add_offset
	print,"missing_value", missing_value
	print, "scale_factor", scale_factor
	print, "add_offset", add_offset

	ncdf_varget,file_id, "lon", lon
	ncdf_varget,file_id, "lat", lat
	ncdf_varget,file_id, "time", time
	ncdf_varget,file_id, "skt", skt

	ncdf_close,file_id

stop
	i1=80
	i2=128
	lon=lon(i1:i2)
	j1=31
	j2=62
	lat=lat(j1:j2)
	l1=0
	l2=12*30-1
	time=time(l1:l2)
	skt=skt(i1:i2,j1:j2,l1:l2)

	nlon=n_elements(lon)
	nlat=n_elements(lat)
	nt=n_elements(time)
	m=nlon*nlat
	d=fltarr(nlon*nlat,nt)
	for l=0,nt-1 do d(*,l)=reform(skt(*,*,l))

	calc_svd,m,m,nt,d,d,u,v,l0,var,c1,c2
	f=fltarr(nlon,nlat)

	!p.multi=[0,1,4]
	for imode=0,3 do begin
	  f(*,*)=u(imode,*)
	  contour,f,lon,lat
	endfor

	end