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

The problem I have is the following:

Let C be a list of coordinates, say, C = {x1, x2, ..., xn} and T be a tensor (possibly with symmetries) defined using the Array command (e.g., for a tensor with $3$ covariant components):

T = Array[ tt, { dim, dim, dim}]

where dim = n.
Now what I want is to declare that each and every component is a function of the coordinates.

Unfortunately, a command like:

T = Array[ tt[ x1, x2, ..., xn], { dim, dim, dim}]

does not work.

Any suggestions?

share|improve this question
Look up Function or Slot. Define tt as tt[x1[#1,#2,#3], x2[...], ...]& – Sjoerd C. de Vries Nov 3 '13 at 23:25

Improving a bit on @Sjoerd C. de Vries comment, you use SlotSequence (##) to do the following:

c = {x1, x2};

T = Array[t[##] @@ c &, {2, 2}]
 {t[1, 1][x1, x2], t[1, 2][x1, x2]}, 
 {t[2, 1][x1, x2], t[2, 2][x1, x2]}

Taking partial derivatives w.r.t. to one of the coordinates (just to name an example) then works as expected:

D[T, x1]

Mathematica graphics

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.