Output function definition as TeXForm with big bracket

Question

I've checked this answer. While it works in Mathematica, the $\LaTeX$ output is weird.

X[x_, y_, z_] := Piecewise[{{3/(4*Pi), Sqrt[x^2 + y^2 + z^2] <= 1}}, 0]
Row[{HoldForm[X[x, y, z]], X[x, y, z]}, "\[LongEqual]"] // TraditionalForm // TeXForm

The $\LaTeX$ output is:

X(x,y,z)=
\begin{array}{cc}
 \{ & 
\begin{array}{cc}
 \frac{3}{4 \pi } & \sqrt{x^2+y^2+z^2}\leq 1 \\
 0 & \text{True} \\
\end{array}
 \\
\end{array}

which renders as:

How could I get something like:

?

Answer 1

You can do

toX[s_]:=ToString@TeXForm[s]
X[x_,y_,z_]:=Piecewise[{{3/(4*Pi),Sqrt[x^2+y^2+z^2]<=1}},0]
toX[HoldForm@X[x,y,z]]<>"="<>toX[X[x,y,z]]

Which gives

X(x,y,z)=\begin{cases}
 \frac{3}{4 \pi } & \sqrt{x^2+y^2+z^2}\leq 1 \\
 0 & \text{True}
\end{cases}

COPY the above from the notebook using plain text to your Latex editor outside of Mathematica:

\documentclass[12pt]{article} 
\usepackage{amsmath}
\begin{document}   
\[
X(x,y,z)=\begin{cases}
 \frac{3}{4 \pi } & \sqrt{x^2+y^2+z^2}\leq 1 \\
 0 & \text{True}
\end{cases}
\]
\end{document}

Compiled using TeXLive gives

---

Or if you have MaTeX installed in Mathematica, you can compile the output without leaving the comfort of the notebook: