% if ndims(A) == 3
% submat(A,i) = A(:,:,i)
% alternative use:
% submat(A,i:j) = A(:,:,i:j)


function B = submat( A, i )    
    
    s = size(A);
    

     if( length(i) > 1 )
         
         len = prod(size(i));
         B = [];         
         for j = 1:len
             B = [B, submat(A, i(j)) ];        
         end
         
         shape = s;
         shape(end) = [];         
         
         shape = [shape, len];
         
         B = reshape(B, shape);
         
         
        return 
     end


    if ( i < 1 || i > s(end) )
       error('Index exceeds matrix dimensions.') 
    end
          
    shape = s(1:end-1);    
    num = prod( shape );
    
    from = (i-1)*num;
    to   = from+num;
    B  = A ( 1+from:to );
    
    
    if length(shape) == 1
        % don't transpose if imput is a 1-d matrix
        if s(1) ~= 1 && s(2) ~= 1
            B = B';
        end
    else
        B = reshape(B , shape);    
    end

end