Mathematica Stack Exchange is a question and answer site for users of Mathematica. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

If I have a vector say for example $\vec{r}(t)=<t,t^2,3t^2>$ and a function $f(x,y,z)=\sqrt{1+30x^2+10y}$ whats the best way to express $f(x,y,z)$ as a function of the parameter $t$?

share|improve this question
It is your duty to upvote answers to your questions (if they are helpful) and accept the best answer if there is anyone deserving it. Otherwise provide more detailed explanation what you expect. – Artes Dec 7 '13 at 2:02

You can use @@:

r[t_] := {t, t^2, 3 t^2}
f[x_, y_, z_] := Sqrt[1 + 30 x^2 + 10 y]
f @@ r[t]
(* Sqrt[1 + 40 t^2] *)

But what is best depends on what you want to do with it later

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.