clc
syms t;
x=@(t)2+t+t^3;
y=@(t)-t-t^3;
z=@(t)5+t^3;
ezplot3(x(t),y(t),z(t));
v=[diff(x(t)),diff(y(t)),diff(z(t))];
acc=[diff(x(t),2),diff(y(t),2),diff(z(t),2)];
d3=[diff(x(t),3),diff(y(t),3),diff(z(t),3)];
k=det([v;acc])/norm(v)^3;

a=input('t=');
d=double(k,t,a);
if(d==0)
    disp('c(t) este varf al curbei');
else
    disp('c(t) nu este varf al curbei');
endif
T=dot(cross(v,acc),d3)/(norm(cross(v,acc))^2)