How to draw 3 components diagram?

Question

I would like to draw the following figure in LaTeX, but I am unable to get any satisfying result with the packages tikz, smartidagram or even graphicx.

I am grateful for any tip and suggestion.

Thank you!

Answer 1

tikz-cd is a convenient package for drawing commutative diagrams relatively easily. It provides macros to facilitate the creation of diagrams instead of using tikz directly which can be quite cumbersome.

\documentclass[12pt,a4paper]{article}
\usepackage{tikz-cd,amsmath}
\begin{document}

\begin{tikzcd}[column sep=small]
& \mathrm{M/M/1} \arrow[dl,leftrightarrow] \arrow[dr,leftrightarrow] & \\
\left.\begin{array}{r@{}}
\lambda_k = \lambda\\[.5em]
\mu_k = \mu
\end{array}\right\} \arrow[rr,leftrightarrow] & & 
\left\{\begin{array}{@{}l}
A(t) = 1-e^{-\lambda t}\\[.5em]
B(x) = 1-e^{-\mu x}
\end{array}\right.
\end{tikzcd}

\end{document}

Answer 2

Welcome to TeX.SE! There are zillions of ways of producing something of this type. Here is one.

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{tikzmark}
\begin{document}
\[\begin{array}{rcl} & \tikzmarknode{M}{M}/M/\tikzmarknode{1}{1} & \\[8mm]
 \left.\begin{array}{r}
   \mathstrut\lambda_k  =\tikzmarknode{l}{\lambda}\\
   \mathstrut\mu_k  =\mu
   \end{array}\!\right\}\tikzmarknode{ls}{\mathstrut}
  & \quad  \quad & \tikzmarknode{rs}{\mathstrut}
  \left\{\!\begin{array}{l}
      \mathstrut\tikzmarknode{A}{A}(t)     =1-\mathrm{e}^{-\lambda t}\\
      \mathstrut B(t)     =1-\mathrm{e}^{-\mu t}
    \end{array}\right.\end{array}
\]
\begin{tikzpicture}[remember picture,overlay]
\draw [latex-latex] (M) -- (l);
\draw [latex-latex] (1) -- (A);
\draw [latex-latex] (ls) -- (rs);
\end{tikzpicture}%
\end{document}

I really hope you find enough motivation and patience to explore these options by yourself. You'll see it's worth it.