function [v1]=convert2gcmfaces(v0,varargin);

aa=whos('v0'); doGcm2Faces=strcmp(aa.class,'double');

if doGcm2Faces;

  if nargin==1; nFaces=5; else; nFaces=varargin{1}; end;

  if nFaces>1;

    nn=size(v0,1); 
    pp=size(v0,2)/nn;
    mm=(pp+4-nFaces)/4*nn; 

    n3=size(v0,3); n4=size(v0,4);

    v00=reshape(v0,[nn*nn*pp n3*n4]);
    i0=1; i1=nn*mm; v1{1}=reshape(v00(i0:i1,:),[nn mm n3 n4]);
    i0=i1+1; i1=i1+nn*mm; v1{2}=reshape(v00(i0:i1,:),[nn mm n3 n4]);
    i0=i1+1; i1=i1+nn*nn; v1{3}=reshape(v00(i0:i1,:),[nn nn n3 n4]);
    i0=i1+1; i1=i1+nn*mm; v1{4}=reshape(v00(i0:i1,:),[mm nn n3 n4]);
    i0=i1+1; i1=i1+nn*mm; v1{5}=reshape(v00(i0:i1,:),[mm nn n3 n4]);
    if nFaces==6;
       i0=i1+1; i1=i1+nn*nn; v1{6}=reshape(v00(i0:i1,:),[nn nn n3 n4]);
    end;

  else;
    v1={v0};
  end;

  if nFaces==1; gridType='ll'; elseif nFaces==5; gridType='llc'; elseif nFaces==6; gridType='cube'; end;
  v1=gcmfaces(v1,gridType);

else;

  nFaces=get(v0,'nFaces');

  if nFaces>1;

    v0_faces=v0; clear v0; 
    for iFace=1:nFaces; eval(['v0{iFace}=get(v0_faces,''f' num2str(iFace) ''');']); end; 

    nn=size(v0{1},1); mm=size(v0{1},2); 
    pp=mm/nn*4+nFaces-4;

    n3=size(v0{1},3); n4=size(v0{1},4);
    v1=NaN*zeros(nn,nn*pp,n3,n4);

    v11=NaN*zeros(nn*nn*pp,n3*n4);
  
   i0=1; i1=nn*mm; tmp1=reshape(v0{1},[nn*mm n3*n4]); v11(i0:i1,:)=tmp1(:,:);
   i0=i1+1; i1=i1+nn*mm; tmp1=reshape(v0{2},[nn*mm n3*n4]); v11(i0:i1,:)=tmp1(:,:);
   i0=i1+1; i1=i1+nn*nn; tmp1=reshape(v0{3},[nn*nn n3*n4]); v11(i0:i1,:)=tmp1(:,:);
   i0=i1+1; i1=i1+nn*mm; tmp1=reshape(v0{4},[mm*nn n3*n4]); v11(i0:i1,:)=tmp1(:,:);
   i0=i1+1; i1=i1+nn*mm; tmp1=reshape(v0{5},[mm*nn n3*n4]); v11(i0:i1,:)=tmp1(:,:);
   if nFaces==6; 
      i0=i1+1; i1=i1+nn*nn; tmp1=reshape(v0{6},[nn*nn n3*n4]); v11(i0:i1,:)=tmp1(:,:);
   end;

   v1=reshape(v11,[nn nn*pp n3 n4]);

  else;
    v1=v0{1}; 
  end;
 
end;