Copy xAct expression to LaTeX

Question

How can I copy an xAct expression to LaTex? Using the usual command TeXForm[] gives the xAct structure, I would like to get the printed form. For example

$$ \text{TeXForm}[\nabla_a\phi\nabla^a\phi] $$

gives

\text{CD}(-a)(p()) \text{CD}(-a)(p())

which is how I defined my tensors.

Answer 1

This imports the package and defines the variables,

<< xAct`xTensor`;

DefManifold[M4, 4, {a, b, c, d, e, f, g, h, i, j, k, l}] ;
DefMetric[-1, metric[-a, -b], CD, PrintAs -> "g"];
DefTensor[p[], M4, PrintAs -> "ϕ"];

This is your expression,

test = (CD[-a]@p[] CD[a]@p[])

Let's look at all the various forms there are of this expression,

Through[{TraditionalForm, TeXForm, InputForm, FullForm, StandardForm}[test]]

It seems that all forms except StandardForm see test as CD[-a][p[]]CD[a][p[]] So we need to apply StandardForm and then TeXForm:

TeXForm@StandardForm@test
(* \left(\triangledown _a\phi
   \right) \left(\triangledown
   ^a\phi \right) *)

Or, evaluated in $\TeX$,

$$\left(\triangledown _a\phi \right) \left(\triangledown ^a\phi \right) $$