[Tex/LaTex] Highlight some portion of an equation

beamertikz-arrowstikz-pgf

Following the instructions of some posts here on stackexchange, I have used the following codes to generate the attached image of an equation. However, I would also like to have the terms inside the square brackets highlighted in blue. In addition, I would like to annotate the first term on the right side of the equation i.e. (1-delta) with highlighting. It's my first time using the tikz package and I am struggling with this terribly. I have already checked out the example from http://www.texample.net/tikz/examples/beamer-arrows. But since I am very new, I could not make much of it.

I will be immensely grateful if someone could help me here with codes and their explanations.

\documentclass[xcolor=dvipsnames]{beamer}
\usetheme{Madrid}
\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{tikz}
\usetikzlibrary{tikzmark, positioning, arrows,shapes}

\begin{document}

\begin{frame}{Household}
with the law of motion of capital,
\begin{equation}
\label{capmot}
K_{t+1}^p= (1-\delta)K_t^P + I_t^P\tikzmark{pdt}{\left[1 - \dfrac{\chi}{2}\left(\dfrac{I_t^P}{I_{t-1}^P} -1 \right)^2 \right]}
\end{equation}
\begin{tikzpicture}[
  remember picture,
  overlay,
  expl/.style={draw=orange,fill=orange!30,rounded corners,text width=3cm},
  arrow/.style={red!80!black,ultra thick,->,>=latex}
]
\node<2->[fill=blue!20,anchor=base,expl] 
  (pdtex) 
  at (6,3.5cm)
  {Investment Adjustment Cost};
\draw<2->[arrow]
  (pdtex.west) to[out=180,in=180] ([yshift=0.5ex]{pic cs:pdt});  
\end{tikzpicture}
\end{frame}
\end{document}

P.S. I require the annotations to appear one by one on click.

Best Answer

Here is a proposal. To change the color to blue, you can use \alert after telling beamer to use blue for \alert. I also change the way you add the box by using a callout and \tikznode for more precise highlighting.

\documentclass[xcolor=dvipsnames]{beamer}
\usetheme{Madrid}
\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{tikz}
\usetikzlibrary{tikzmark, positioning, arrows,shapes}
\usetikzlibrary{shapes.callouts,shadows.blur,positioning}
\usetikzlibrary{overlay-beamer-styles}
\setbeamercolor{alerted text}{fg=blue}
\newcommand{\tikznode}[2]{\relax
\ifmmode%
  \tikz[remember picture,baseline=(#1.base),inner sep=0pt] \node (#1) {$#2$};
\else
  \tikz[remember picture,baseline=(#1.base),inner sep=0pt] \node (#1) {#2};%
\fi}

\begin{document}

\begin{frame}{Household}
with the law of motion of capital,
\begin{equation}
\label{capmot}
K_{t+1}^p= \alert<2>{\tikznode{del}{(1-\delta)}}K_t^P + 
I_t^P\alert<3>{\tikznode{pdt}{\left[1 -
\dfrac{\chi}{2}\left(\dfrac{I_t^P}{I_{t-1}^P} -1 \right)^2 \right]}}
\end{equation}
\begin{tikzpicture}[
  remember picture,
  overlay,
  expl/.style={draw=orange,fill=orange!30,rounded corners,text width=3cm},
  arrow/.style={red!80!black,ultra thick,->,>=latex}
]
\node[alt={<2>{drop shadow,opacity=0.8,text opacity=1}{invisible}},
visible on=<2>, 
align=center, fill=blue!20, align=center, 
rounded corners,draw,rectangle callout,
anchor=pointer,callout relative pointer={(-300:1cm)}]
at (del) {Depreciation};
\node[alt={<3>{drop shadow,opacity=0.8,text opacity=1}{invisible}},
visible on=<3>, 
align=center, fill=blue!20, align=center, 
rounded corners,draw,rectangle callout,
anchor=pointer,callout relative pointer={(230:1cm)}]
at (pdt.north) {Investment Adjustment Cost};
\end{tikzpicture}
\end{frame}

\end{document}

Related Solutions

[Tex/LaTex] Rotate a node but not its content: the case of the ellipse decoration

The source of the difficulty is that ellipses are constructed in a particular way in TikZ. They are paths that start from the x-axis and proceed counter-clockwise around their centre. The vast majority of the time, the exact parametrisation doesn't matter. You appear to have found the one situation where it does!

In the actual question, you only want to be able to mirror the ellipse, and so draw it starting from the negative x-axis (the title of the question suggests a more flexible approach). That's actually not too hard since we can exploit the symmetry of the ellipse. The key is to provide it with a negative x-radius, since then it will start from the negative x-axis (and proceed clockwise, but we could correct for that by negating the y-radius as well). To do this, we interrupt the call from the node shape to the drawing command and flip the sign of the x-radius. The simplest way to do this is to redefine the \pgfpathellipse macro to do the negation and then call the original macro. The following code does this.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations,shapes,decorations.markings}
\makeatletter
\let\origpgfpathellipse=\pgfpathellipse
\def\revpgfpathellipse#1#2#3{%
  #2%
  \pgf@xa=-\pgf@x
  \origpgfpathellipse{#1}{\pgfqpoint{\pgf@xa}{0pt}}{#3}}
\makeatother

\tikzset{
  reversed ellipse/.style={
    ellipse,
    reverse the ellipse%
  },
  reverse the ellipse/.code={
    \let\pgfpathellipse=\revpgfpathellipse
  }
}
\begin{document}
\begin{tikzpicture}
\node[ellipse,
  draw,
  postaction={
    decorate,
    decoration={
      markings,
      mark=at position 1 with {
        \arrow[line width=5pt,blue]{>}
      }
    }
  }
] at (0,0) {hello world};

\node[reversed ellipse,
  draw,
  postaction={
    decorate,
    decoration={
      markings,
      mark=at position 1 with {
        \arrow[line width=5pt,blue]{>}
      }
    }
  }
] at (0,-2) {hello world};
\end{tikzpicture}

\end{document}

Here's the result:

rotated ellipse

(the arrow got clipped, but you can see where it lies)

[Tex/LaTex] Numerical conditional within tikz keys

I am definitely unfamiliar with both beamer and tikz (do not quite get what the \only are supposed to do) but perhaps this could go in the direction you want:

\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{chains}
\newcounter{count}

% helper macro:
\long\def\GobToSemiColon #1;{}

\newcommand\myPicture{
\begin{tikzpicture}
  \begin{scope}[start chain = going below]
  \ifnum\value{count}<1 \expandafter\GobToSemiColon\fi
  \ifnum\value{count}>3 \expandafter\GobToSemiColon\fi
  \node[draw, rectangle, on chain] {display only when counter is between
    1 and 3};

  \ifnum\value{count}>-1 \expandafter\GobToSemiColon\fi
  \node[draw, rectangle, on chain] {display only when counter is
    negative}; 

  \ifnum\value{count}<100 \expandafter\GobToSemiColon\fi
  \ifnum\value{count}>200 \expandafter\GobToSemiColon\fi  
  \node[draw, rectangle, on chain] {display only if counter is between
    100 and 200};

  \ifnum\value{count}<3 \expandafter\GobToSemiColon\fi
  \ifnum\value{count}>20 \expandafter\GobToSemiColon\fi
  \node[draw, circle, on chain] {only when counter is in the range 3 to 20};
  \end{scope}
\end{tikzpicture}
}

\begin{document}
\begin{frame}
\only{\setcounter{count}{-3}\myPicture}
\only{\setcounter{count}{105}\myPicture}
\only{\setcounter{count}{39}\myPicture}
\only{\setcounter{count}{2}\myPicture}
\only{\setcounter{count}{5}\myPicture}
\end{frame}
\end{document}

beamer

Best Answer

Related Solutions

[Tex/LaTex] Rotate a node but not its content: the case of the ellipse decoration

[Tex/LaTex] Numerical conditional within tikz keys

Related Question