g.m

function out  =g(x,NL,k,var_v_node)
% Delta : x_column []
[N,M]=size(NL);
out=0;



for l=1:N
      
    if(l~=k && NL(l,k)==1)
      
            if ((x(:,l)-x(:,k))==0)
               out_sum=0;
            else
             out_sum=(var_v_node(l,1)-var_v_node(k,1))*(x(:,l)-x(:,k))/norm(x(:,l)-x(:,k));
            end
        
    out=out+out_sum;
    
    end
  
    
end
out=-out;
    
    
end