find out center of stiffness for a building

for i=1:1:ne
    ckx(i)=xf;
    cky(i)=yf;
    b=12*Ec(i).*Iyy(i)/(L(i).^3);
    c=12*Ec(i).*Izz(i)/(L(i).^3);
    d=b.*xcgf(i);
    e=(c.*(xcgf(i)).^2)+(b*(ycgf(i)).^2);
    eval(['h',num2str(i),'l','=[b,0,d;0,c,0;d,0,e]']);
    h=[b,0,d;0,c,0;d,0,e];
    f=elem(i,4);%Floor Number
    eval(['k',num2str(i),'l','=[h,-h;-h,h]']);
end 

% center of stiffness of each floor level
for fl=1:1:dof(de,4)
 for i=1:1:ne
    CKx(fl)=sum(ckx(i).*k(i))./sum(k(i));
    CKy(fl)=sum(cky(i).*k(i))./sum(k(i));
    CKz(fl)=sum(ckz(i).*k(i))./sum(k(i));
 end
end
%% it is showing undefied K during the running. What are the error in this coading?