B-Spline & NURBS (Matlab Code)

There are some errors in the code, anyone can help me to find and tell me?

Thanks a lot!

 

% % % --------------------------------
% % % Author: begtostudy
% % % MSN:begtostudy@hotmail.com
% % % Email : begtostudy@gmail.com
% % % --------------------------------
function Q = bspline( P,U ,t,w)
% B-Spline interpolation for given points.
 
    if (nargin==2)
      w=ones(1,size(P,2));
    end
    for k=1:length(t)
        Q(:,k)=[0 0 0]';
        rational=0;
        for j=1:size(P,2)
            tmp=deboor(U,size(P,2)-1,j,t(k));
            if (nargin==3)
                rational =rational+w(j)*tmp;
            end
            Q(:,k)=Q(:,k)+w(j)*P(:,j)*tmp;
        end
        if (nargin==3)
            Q(:,k)=Q(:,k)/rational;
        end
    end
end
 
function N=deboor(U,k,i,u)
    if isequal(k,1)
        if (abs(U(i)-U(i+1))<1e-6) && (abs((U(i)-u))<1e-6) 
            N=1;        
        elseif u>=U(i) && u<U(i+1)
            N=1;
        else
            N=0;
        end
    else
        N=division(u-U(i),U(i+k)-U(i))*deboor(U,k-1,i,u)...
        +division(U(i+k+1)-u,U(i+k+1)-U(i+1))*deboor(U,k-1,i+1,u);
    end
end
 
function d=division(a,b)
    if (abs(a)<1e-6) && (abs(b)<1e-6) 
        d=0;
    else
        d=a/b;
    end
end