# How to create this diagram(equation with labels) with Tikz?

I'm not sure how to create the following diagram with Tikz

I thought of using nodes, but I'm not sure how we would go about it...

• This is not too hard to do. But as it sits here your question is more of the type please do this for me which is disliked here as this is a Q'n'A site not a "sweatshop", you should at least show some initiative and provide something others can work with.. You can probably mess about with this answer using tikzmark: tex.stackexchange.com/questions/209052/… – daleif Jan 17 at 14:47
• @daleif Thanks for the info. I'll check tikzmark. (I didn't know it existed even...) – An old man in the sea. Jan 17 at 14:49
• Is it necessary to realize your image with TikZ? – Sebastiano Jan 17 at 21:43
• @Sebastiano no it's not. ;) – An old man in the sea. Jan 17 at 23:25

Something to get started in the right direction --adapted from

http://www.texample.net/tikz/examples/global-nodes/

\documentclass{article}

\usepackage{tikz}
\usepackage{amsmath}
\usetikzlibrary{arrows}
\begin{document}
\pagestyle{empty}

% For every picture that defines or uses external nodes, you'll have to
% apply the 'remember picture' style. To avoid some typing, we'll apply
% the style to all pictures

\tikzstyle{every picture}+=[remember picture]

% By default all math in TikZ nodes are set in inline mode. Change this to
% displaystyle so that we don't get small fractions

\everymath{\displaystyle}

\begin{itemize}
\item Physical Experiment Response
\tikz\node [fill=blue!20,draw,circle] (n1) {};
\end{itemize}

% Below we mix an ordinary equation with TikZ nodes. Note that we have to
% adjust the baseline of the nodes to get proper alignment with the rest of
% the equation

$$\tikz[baseline]{ \node[fill=blue!20,anchor=base] (t1) {y^e(x)}; } = \tikz[baseline]{ \node[fill=red!20,anchor=base] (t2) {y^m(x,\theta^*)}; }$$

\begin{itemize}
\item Computer Model Response
\tikz\node [fill=red!20,draw,circle] (n2) {};
\end{itemize}

% Now it's time to draw some edges between the global nodes. Note that we
% have to apply the 'overlay' style

\begin{tikzpicture}[overlay]
\path[->] (n1) edge [bend left] (t1);
\path[->] (n2) edge [bend right] (t2);
\end{tikzpicture}

\end{document}