% mesh-independency filter
function [dcn]=check(nelx,nely,rmin,x,dc)
dcn=zeros(nely,nelx);
for i=1:nelx
    for j=1:nely
        sum=0.0;
        for k=max(i-floor(rmin),1):min(i+floor(rmin),nelx)
            for l=max(j-floor(rmin),1):min(j+floor(rmin),nely)
                fac=rmin-sqrt((i-k)^2+(j-l)^2);
                sum=sum+max(0,fac);
                dcn(j,i)=dcn(j,i)+max(0,fac)*x(l,k)*dc(l,k);
            end
        end
        dcn(j,i)=dcn(j,i)/(x(j,i)*sum);
    end
end