**> restart;**

**> with(plots):**

**> dp := proc(X,Y)**

**> X[1]*Y[1]+X[2]*Y[2];**

**> end:**

**> nrm := proc(X)**

**> sqrt(dp(X,X));**

**> end:**

**> r:=[3*cos(u),3*sin(u)];**

**> lambda:=1;**

**> f:=proc(X)**

**> local Xu,s,T,N,kappa,v,n,pr,v1,z;**

**> Xu := [diff(X[1],u),diff(X[2],u)];**

**> s := nrm(Xu);**

**> T:=[diff(X[1],u)/s,diff(X[2],u)/s];**

**> N:=[-T[2],T[1]];**

**> kappa:=simplify(dp(diff(T,u),N))/s;**

**> v:=int(kappa,u=0..u);**

**> z:=v;**

**> if z=0 then -1 else v1:=z fi;**

**> n:=[cos(v1)*N[1]+sin(v1)*T[1],cos(v1)*N[2]+sin(v1)*T[2]];**

**> pr:=([r[1]+lambda*n[1],r[2]+lambda*n[2]]);**

**> end:**

**> plot([f(r)[1],f(r)[2],-18..18]);**

**can you please help me , I'm not sure what is going wrong.**