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);
    for i3=1:n3; for i4=1:n4;
      v00=v0(:,:,i3,i4);

      v00=v00(:);
      i0=1; i1=nn*mm; v1{1}(:,:,i3,i4)=reshape(v00(i0:i1),nn,mm);
      i0=i1+1; i1=i1+nn*mm; v1{2}(:,:,i3,i4)=reshape(v00(i0:i1),nn,mm);
      i0=i1+1; i1=i1+nn*nn; v1{3}(:,:,i3,i4)=reshape(v00(i0:i1),nn,nn);
      i0=i1+1; i1=i1+nn*mm; v1{4}(:,:,i3,i4)=reshape(v00(i0:i1),mm,nn);
      i0=i1+1; i1=i1+nn*mm; v1{5}(:,:,i3,i4)=reshape(v00(i0:i1),mm,nn);
      if nFaces==6;
         i0=i1+1; i1=i1+nn*nn;
      end;

    end; 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);
    for i3=1:n3; for i4=1:n4;

      v11=NaN*zeros(nn*nn*pp,1);
    
      i0=1; i1=nn*mm; tmp1=v0{1}(:,:,i3,i4); v11(i0:i1)=tmp1(:);
      i0=i1+1; i1=i1+nn*mm; tmp1=v0{2}(:,:,i3,i4); v11(i0:i1)=tmp1(:);
      i0=i1+1; i1=i1+nn*nn; tmp1=v0{3}(:,:,i3,i4); v11(i0:i1)=tmp1(:);
      i0=i1+1; i1=i1+nn*mm; tmp1=v0{4}(:,:,i3,i4); v11(i0:i1)=tmp1(:);
      i0=i1+1; i1=i1+nn*mm; tmp1=v0{5}(:,:,i3,i4); v11(i0:i1)=tmp1(:);
      if nFaces==6; 
         i0=i1+1; i1=i1+nn*nn;
      end;

      v1(:,:,i3,i4)=reshape(v11,nn,nn*pp);
    end; end;

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